MGA3000 Multi-Gas Analyser Operation Manual Iss. 3.01
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MGA3000C MULTI-GAS ANALYSER
OPERATION MANUAL Version 3.01
MGA3000 Multi-Gas Analyser Operation Manual Iss. 3.01
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Health and Safety Information __________________________________________________________
Equipment Operation Use of this instrument in a manner not specified by ADC Gas Analysis Ltd may be hazardous.
Electrical Power Supply Before working on the electrical connections all of the electrical power lines to the equipment
must be isolated. All the electrical cables and signal cables must be connected exactly as
indicated in these operating instructions. If in doubt contact ADC Gas Analysis Ltd.
Face and Eye Protection Suitable face and eye protection must be worn when working on hot vessels and ducts!
Special safety measures must be taken when working on a high pressure duct.
Protective Clothing Protective clothing must always be worn when working in the vicinity of hot vessels or ducts.
Storage The instrument should be stored in its packaging, in a dry and sheltered area.
Unpacking Check all packaging for external signs of damage. Check the contents against the packing
note.
Return of Damaged Goods IMPORTANT
If any item has been damaged in transit, this should be reported to the carrier and to the
supplier immediately. Damage caused in transit is the responsibility of the carrier not the
supplier.
DO NOT RETURN a damaged instrument to the sender as the carrier will not then consider
a claim. Save the packing with the damaged article for inspection by the carrier.
Return of Goods for Repair If you need to return goods for repair please contact our Customer Service Department.
They will be able to advise you on the correct returns procedure.
Any item returned to ADC Gas Analysis Ltd should be adequately packed to prevent damage
during transit.
You must include a written report of the problem together with your own name and contact
information, address, telephone number, email address etc.
Lifting Instructions Where items are too heavy to be lifted manually, use suitably rated lifting equipment. Refer
to the Technical Specification for weights. All lifting should be done as stated in local
regulations.
MGA3000 Multi-Gas Analyser Operation Manual Iss. 3.01
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Design and Manufacturing Standards __________________________________________________________
The Quality Management system of ADC Gas Analysis Ltd is approved to BS
EN ISO 9001 for the design, manufacture and on-site servicing,
environmental monitoring and non-contact temperature measuring
instrumentation.
The instrument complies with current European directives relating to
Electromagnetic Compatibility 89/336/EEC and Low voltage Directive
73/23/EEC.
Operation of radio transmitters, telephone or other electrical/electronic devices in close
proximity to the equipment while the enclosure doors of the instrument or its peripherals are
open, may cause interference and possible failure where the radiated emissions exceed the
EMC directive.
The protection provided by both CE and IP classifications to this product may be invalidated if
alterations are made to the structural, electrical, mechanical or pneumatic parts of this
system. Such changes may also invalidate the standard terms of warranty.
Dimensions
Unless otherwise stated, all measurements are given in millimetres and inches.
Copyright
This manual is provided as an aid to owners of ADC Gas Analysis products and contains
information proprietary. This manual may not, in whole or part, be copied, or reproduced
without the expressed written consent of ADC Gas Analysis Ltd
©copyright 2010 ADC Gas Analysis Ltd
Caution, risk of electric shock
Caution, attention to possibility of risk of damage to the product, processes or
surroundings. Refer to instruction manual.
Protective Conductor Terminal
Caution, hot surface
Observe precautions for handling electrostatic discharge sensitive devices
This item or material can be recycled
MGA3000 Multi-Gas Analyser Operation Manual Iss. 3.01
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How to Get Further Assistance _________________________________________________________
If further assistance is required please contact your nearest Gas Analysis Led office the
following addresses or your local distributor (see our website for details http://www.adc-
service.co.uk)
United Kingdom
ADC Gas Analysis Ltd
Unit 35 Hoddesdon Industrial Centre
Pindar Road
Hoddesdon
Herts, EN11 0FF
Australia
Anri Instruments & Controls Pty Ltd
Unit 29
756-758 Burwood Highway
Ferntree Gully
Victoria, VIC 3156
Australia
United States of America
CEA Instruments Inc
160 Tillman Street
Westwood
New Jersey, NJ077675
France
Gruter et Marchand
22/24 Rue Lavoisier
92000 Nanterre
Fermanagh
Gas Monitoring Services
4 Second Street
Boksburg North 1459
South Africa
Macro Group Enterprise Co Ltd
Room 906
No 432 Keelung Road, Sec 1
Taipei
Taiwan
When contacting ADC please have the following information available:
Instrument Serial Number.......................
Instrument Part Number.........................
Instrument Name and Model....................
Power supply, voltage and frequency........
This information is found on the rating plate of each instrument.
ADC Gas Analysis Ltd has a comprehensive range of analysers and Environmental Monitoring
Instrumentation.
MGA3000 Multi-Gas Analyser Operation Manual Iss. 3.01
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CONTENTS
Contents .............................................................................................................. 5
1. Introduction ...................................................................................................... 8
1.1 About the Instrument .............................................................................................. 8 1.2 Instrument Identification .......................................................................................... 8 1.3 The Display & Operating Controls .............................................................................. 8
1.3.1 The Display ...................................................................................................... 8 1.3.2 Design ............................................................................................................. 9 1.3.3 The Operating Controls ...................................................................................... 9
1.4 Electrical Outputs .................................................................................................... 9 1.4.1 Analogue Outputs ............................................................................................. 9 1.4.2 Alarm(trips) outputs .......................................................................................... 9 1.4.3 RS232 port ....................................................................................................... 9
1.5 Gas Path .............................................................................................................. 10 1.5.1 Gas Flow Diagram ........................................................................................... 10 1.5.2 Key to gas path figures .................................................................................... 11 1.5.3 Gas connections .............................................................................................. 11 1.5.4 MGA 3000 19” rack, infrared component with oxygen measurement .................... 12
1.6 Dimension drawings .............................................................................................. 13 1.7 Circuit diagrams (electric and gas connections) ........................................................ 14
1.7.1 RS-232C I/O (see section 2.4) .......................................................................... 14 1.7.2 Trip I/O(see section 2.6) .................................................................................. 14 1.7.3 Analogue Output(see section 2.5) ..................................................................... 15
1.8 Operating Principles ............................................................................................... 16 1.8.1 Infrared Absorption ......................................................................................... 16 1.8.2 The Optical Bench In Use ................................................................................. 16 1.8.3 The Oxygen Sensor in Use ............................................................................... 17
2. Installation ..................................................................................................... 19
2.1 Installation Arrangement ........................................................................................ 19 2.2 Location & Ambient Conditions ............................................................................... 19 2.3 Power Supply Setting & Connections ....................................................................... 19
2.3.1 Power Supply Setting ...................................................................................... 19 2.3.2 Power Supply Connections ............................................................................... 20
2.4 Serial I/O (RS232C) .............................................................................................. 20 2.5 Analogue Outputs .................................................................................................. 21 2.6 Alarm (Trip) Outputs ............................................................................................. 22 2.7 Gas Arrangements................................................................................................. 22
2.7.1 The Gas Circuit ............................................................................................... 22 2.7.2 The Sample Gas .............................................................................................. 23 2.7.3 The Span Gas ................................................................................................. 23 2.7.4 The Zero Gas .................................................................................................. 23 2.7.5 The Purge/bypass Gas ..................................................................................... 24 2.7.6 The Exhaust Gas ............................................................................................. 24 2.7.7 Gas Pump(s) .................................................................................................. 24
2.8 Use of Chemicals (certain models only) ................................................................... 24 2.8.1 Water Vapour ................................................................................................. 24 2.8.2 Carbon Dioxide ............................................................................................... 25 2.8.3 Precautions .................................................................................................... 25
2.9 Pre-operation Checks ............................................................................................. 25 2.10 General Advice .................................................................................................... 25
2.10.1 Use of Gas Cylinders ...................................................................................... 25 2.10.2 Gas Leaks ..................................................................................................... 26 2.10.3 Exhausting & Ventilation ................................................................................ 26
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3. Setting Up ...................................................................................................... 27
3.1 Preview ................................................................................................................ 27 3.2 On Power Up ......................................................................................................... 27 3.3 Zero & Span Operations. ........................................................................................ 27 3.4 Display & Keypad .................................................................................................. 28
3.4.1 Display ........................................................................................................... 28 3.4.2 Function Keys ................................................................................................. 29 3.4.3 Menu tree ....................................................................................................... 30
3.5 Analogue (Chart) Outputs ...................................................................................... 31 3.6 Alarm (Trip) Outputs ............................................................................................. 31
3.6.1 Setting Alarm Outputs ..................................................................................... 31 3.7 RS232C Serial Port ................................................................................................ 32
3.7.1 Protocol.......................................................................................................... 32 3.7.2 Serial Port Settings .......................................................................................... 32
3.8 Measurement ........................................................................................................ 33
4. Calibration ...................................................................................................... 34
4.1 Initial Checks ........................................................................................................ 34 4.1.1 Warm Up........................................................................................................ 34
4.2 Zero Adjustment ................................................................................................... 34 4.2.1 Manual Zero ................................................................................................... 35 4.2.2 Auto Zero ....................................................................................................... 35
4.3 Span Adjustment .................................................................................................. 35 4.3.1 Setting Span ................................................................................................... 36 4.3.2 Auto Span ...................................................................................................... 36
5. Maintenance ................................................................................................... 38
5.1 Routine Checks ..................................................................................................... 38 5.1.1 Water Vapour ................................................................................................. 38 5.1.2 Dust .............................................................................................................. 38
5.2 Instrument Checks ................................................................................................ 39 5.2.1 Source Block Purge (when fitted) ...................................................................... 39 5.2.2 Filter Column (when fitted) .............................................................................. 39 5.2.3 Sample Flow ................................................................................................... 39 5.2.4 Throttles ........................................................................................................ 39
6. Optical Bench Descriptions ............................................................................... 40
6.1 Introduction .......................................................................................................... 40 6.2 GC Bench ............................................................................................................. 40
7. Electrical Specifications .................................................................................... 42
7.1 Power Supply ........................................................................................................ 42 7.2 Analogue Outputs .................................................................................................. 42
7.2.1 Set for current output ...................................................................................... 42 7.3 Alarm (Trip) Contacts ............................................................................................ 42 7.4 Serial (RS 232) Port .............................................................................................. 42
8. Spare Parts..................................................................................................... 43
9. „AK‟ Remote Control Protocol ............................................................................ 44
9.1 Introduction .......................................................................................................... 44 9.2 Protocol Overview ................................................................................................. 44 9.3 Address ................................................................................................................ 45 9.4 Commands and Parameters ................................................................................... 45 9.5 Response To Commands ........................................................................................ 45
9.5.1 Status Codes .................................................................................................. 46 9.6 Command descriptions........................................................................................... 46
9.6.1 Interrogation Commands ................................................................................. 46 9.6.2 Show model and version information ................................................................ 46
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9.6.3 Show range information ................................................................................... 46 9.6.4 Show Calibration Information ........................................................................... 47 9.6.5 Show sample gas inlet ..................................................................................... 48 9.6.6 Show analyser gas flow and sample pump state ................................................. 48 9.6.7 Show Alarm and Valve States ........................................................................... 48 9.6.8 Show analyser's gas name(s) ........................................................................... 49
9.7 Remote Control Commands .................................................................................... 49 9.7.1 Set remote control mode ................................................................................. 49 9.7.2 Set local control mode ..................................................................................... 49
9.8 Measurement Enquiry Commands ........................................................................... 50 9.8.1 Get current readings........................................................................................ 50
9.9 Range Selection .................................................................................................... 50 9.9.1 Select active range .......................................................................................... 50
9.10 Gas Inlet Control Commands ................................................................................ 50 9.10.1 Select sample inlet ........................................................................................ 50 9.10.2 Select zero gas ............................................................................................. 51 9.10.3 Select span gas ............................................................................................. 51 9.10.4 Sample pump control .................................................................................... 51
9.11 Calibration Commands ......................................................................................... 51 9.11.1 Perform auto-zero ......................................................................................... 51 9.11.2 Set span gas concentration ............................................................................ 52 9.11.3 Perform span calibration ................................................................................ 52
10. Implementation notes .................................................................................... 54
11. Known Issues ............................................................................................... 55
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1. INTRODUCTION
IMPORTANT
Before operating the Instrument for the first time, ensure all the relevant
installation checks have been carried out [refer to Section 2.9].
1.1 About the Instrument
The MGA3000C Series Instrument is designed for bench or rack mounting and provides a
measurement of gas concentration according to specific user requirements.
Single, dual, triple and 4 gas versions are available utilising one or more IRGA optical
benches and/or chemical cells.
Most instruments incorporate IRGA benches that generate a signal proportional to the
infrared absorption of the measured gas. Providing the gas concentration lies within the
designed range of the instrument, the signal is periodically compared with reference gas
(usually at zero and a convenient mid-span condition). Calibration is achieved manually via
simple front panel controls or fully automatically within the software configuration.
Some instruments may include a chemical cell which reacts with the specific gas and which
provides an electrical output in proportion to the reaction.
Gas concentrations are indicated on a front display panel together with both analogue and
digital signal outputs.
Gas connections to and from the instrument are via suitable fittings on the rear panel. The
gas flow is maintained via an internal sample pump.
The MGA3000's electrical supply can be with any voltage from 90-240V AC and 50/60Hz
1.2 Instrument Identification
Each Instrument is uniquely identified with a Serial Number. This is located on a label on the
rear panel alongside the Model Number for the particular Instrument.
Always quote the serial number and model number in any communications
requiring after sales support.
1.3 The Display & Operating Controls
1.3.1 The Display
The display is a LCD Graphic type that is illuminated
from behind to achieve good contrast and visibility.
Its primary function is to provide large character
readouts of the gas concentrations together with
sample flow status and key functions.
Figure 1 - An example main screen (Multi gas model)
HCL
NOX
CO
SO2
PP
M
PP
M
PP
M
PP
M
2.2
16.2
21.2
18.1
Range
Calib
Set Up
Stp.Pump
*Notes: Flow display can be optional with related flow
switch range (Currently, 200 ㎖/min is installed.)
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1.3.2 Design
1.3.3 The Operating Controls
The operating controls are menu driven and accessed by the 4 keys on the keypad adjacent
to the LCD display. The individual functions of the keys are clearly labelled on the display.
Selecting a menu function (by pressing the appropriate key) will cause the function to be
selected, or the next menu to be displayed, as required. In general, the bottom menu key is
used to return to the previous menu, acknowledge a message, or cancel an operation.
1.4 Electrical Outputs
1.4.1 Analogue Outputs
MGA series analysers have up to four analogue outputs, numbered 1 to 4 for connection
purposes. One output is provided for each of the gas channels fitted. When fewer than four
gas channels are fitted, one or more outputs will be inactive or not connected.
1.4.2 Alarm(trips) outputs
Up to five alarm contacts are provided to indicate gas readings above/below/outside user set
concentrations
1.4.3 RS232 port
An industry-standard serial port is fitted to the rear panel to allow gas readings to be read
and zero to be set by a PC or other computer equipment.
Switch internal pump
on and off:
Pump flowrate adjustable via menu
CAL Key to start
AUTOCAL with ambient air or N2
Dimension freely selectable to
Program (PPM, ppm, mg/m3 )
Status display “AR” or OR”
Status display “Flow” Failure
Component for measured
value, dimension and
component name
*Notes: Flow display can be optional with related flow switch
range (Currently, 200 ㎖/min is installed.)
LCD Display Flowmeter in conjunction with sample pump for mounting the sample gas flow
Setting to component for
measured value, unit, cal
period, etc…
*
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Figure 2 – Gas Flow Diagram
1.5 Gas Path
1.5.1 Gas Flow Diagram
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1.5.2 Key to gas path figures
1.5.3 Gas connections
1. Inlet to sample gas
2. Inlet for AUTOZERO/ zero gas
3. Calibration gas
4. Gas outlet
5. Sample gas pump
6.
6. Solenoid valve for zero
7. Solenoid valve for span
8. Oxygen measuring cell(Option)
9. Sample flow sensor
10. Infrared measuring cell
11. Safety fine filter
▣ Gas connections: stubs 6.35mm or 1/4”
Sample gas Inlet Zero gas Inlet
Span gas Inlet
Sample gas Outlet
Analogue Output
RS-232 Serial output Trips(Alarm) output
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1.5.4 MGA 3000 19” rack, infrared component with oxygen measurement
☞ Connections: 6.35mm or 1/4”
Power supply and fuse
9-pin socket
RS-232
Trips (Alarm)
Digital output
Relay output(N/C, N/O)
Gas outlet
Connections 6mm or 1/4”
Sample gas Inlet
1.0 ℓ /min, 0.3Bar
Zero gas Inlet/AUTOCAL gas
(Gas pressure above 0.3Bar / 5psig
will damage the instrument.)
Span gas Inlet
(Gas pressure above 0.3Bar / 5psig
will damage the instrument.)
Figure 4 – MGA 3000 19” Rear View
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1.6 Dimension drawings
MGA 3000, 19” unit, dimension in mm
664 66 44 480
266
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1.7 Circuit diagrams (electric and gas connections)
1.7.1 RS-232C I/O (see section 2.4)
Serial (RS232C) Port Connections SUB-D 9F
Pin Name Function
1 - no connection
2 Rx Received data (input)
3 Tx Transmitted data (output)
4 DTR Handshake for Rx (output)
5 Ground 0V (nominally chassis)
6 - no connection
7 RTS „true‟ whenever unit is powered
8 CTS Handshake for Tx (input)
9 - no connection
Notes:
1. DTR is normally „true‟
2. CTS is monitored only when „hardware handshake‟ is selected
3. Screened cables must be used for RS232 connections
1.7.2 Trip I/O(see section 2.6)
Trips(Alarm) Port Connections SUB-D 15F
Pin Name Function
1 Trip1 Trip 1 contact A
2 Trip2 Trip 2 contact A
3 Trip3 Trip 3 contact A
4 Trip4 Trip 4 contact A
5 Trip5 Trip 5 contact n/o
6 Trip5 Trip 5 contact n/c
7 +25V Out +25V Output(500mA Max)
8 Trip1 Trip 1 contact A
9 Trip2 Trip 2 contact A
10 Trip3 Trip 3 contact A
11 Trip4 Trip 4 contact A
12 Trip5 Trip 5 contact A
13 None (not connected)
14 +25V return 25V return
15 None (not connected)
Notes:
1. Screened cables must be used for “SUB-D 15” Female connections
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1.7.3 Analogue Output(see section 2.5)
NOTES:
1. I is used to indicate pin functions when output is set to 4..20mA mode
2. Screened cable should be used for analogue output connections (screen to connector
shell).
Analogue Output Pin Connections
Pin Function
1 I output 4 sink
2 I output 3 +ve / I output 3 source
3 I output 1 +ve / I output 1 source
4 I output 3 sink
5 I output 2 sink
6 I output 4 +ve / I output 4 source
7 I output 2 +ve / I output 2 source
8 I output 1 sink
shell 0V (connected to chassis)
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1.8 Operating Principles
1.8.1 Infrared Absorption
With the exception of Oxygen, the instrument measures gas concentrations using the effect
of infrared absorption.
All heteroatomic gases absorb (or transmit) light energy in the infrared region at specific
wavelengths that are dependent upon the chemical composition of each type of gas.
Furthermore, the level of absorption is proportional to the mass of the gas present. This
characteristic is utilised in infrared gas analysis (IRGA) benches.
The benches incorporate a source of infrared energy (usually in the form of a heated
filament), which is then optically filtered to reduce the radiation spectrum to that of the
absorption band of the gas being measured.
A pyro-electric detector is used to measure the difference in energy between a reference zero
(no absorption) condition and that after some absorption in the gas has occurred. By
calibrating the bench at the zero condition and a known span concentration, a reliable
measure of concentration over the span range is obtained.
To improve the stability and to assist in the detection process, the infrared source is
modulated mechanically at 3-18Hz depending on the type of bench being used.
The relationship between absorption and concentration is not linear. For this reason the non-
linear output from the detector is modified electronically to give a linear output to the chart
recorder and display outputs.
The performance of an IRGA bench is compromised by the presence of 'interference' gases in
the sample. Such gases, of which the most common is water vapour, have an overlapping
infrared response to that of the measured gas and their effects are minimised by careful
filtering and the selection of the absorption band.
The level of absorption measured is relative and therefore an IRGA provides a comparative
measurement, not an absolute one, against 'zero' and 'span' reference gases.
A 'zero' gas has no detectable concentration of the gas being measured. Depending on the
gas, fresh air, chemically stripped air or nitrogen may be used. A 'span' gas has a known
concentration of the measured gas and is used to set the gain (or span) of the analysis in the
mid-range region. Under normal circumstances, the concentration is equivalent to about 80%
of the displayed full-scale reading.
1.8.2 The Optical Bench In Use
In order to obtain and maintain the optimum performance from the instrument, a number of
guidelines are offered associated with the use of the instrument, and, in particular, those
elements under the control of the User.
The IRGA bench is essentially an optical system and can suffer some deterioration in the
performance if it is internally contaminated by the condition of the incoming gases.
The gas sample should be reasonably dry. If the presence of water vapour is or is not
expected it is recommended that the instrument is continuously switched 'ON' to prevent
condensation.
The flow rate of the gas sample affects the response time (to change) of the measurement -
the measurement being on average the mix of the sample flowing through the cell. In
practice a sample flow rate of nominally 500 ml/min1 provides satisfactory performance for
MGA3000 Multi-Gas Analyser Operation Manual Iss. 3.01
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any instrument. The instrument is fitted with a flow sensor and the flow rate is indicated on
the display. There is a potentiometer and throttle fitted internally that allows this flow rate to
be reset if necessary.
Generally the sample gas will be pumped to achieve the required flow rate. An internal pump
is fitted in the instrument and can be switched on or off via the key labelled „pump‟ on the
front panel. It is recommended that the pump is switched 'OFF' if the sample lines are being
attended to or the condition of the sample gas is suspect (for example it contains water).
The sample rate is factory pre-set for sample gas at ambient pressure.
The installation of pressurised cylinders must include suitable pressure regulators and
carefully controlled to avoid damage to pump or flow sensor due to over-pressure.
The instrument must be allowed to 'temperature stabilise' after first being switched on. The
display will show a thermometer symbol until the associated bench has reached operating
temperature. The instrument's enclosure plays a role in temperature control as well as
providing protection and the enclosure (top and front) should be securely in place before use.
Unless the instrument is only used occasionally it is advisable to leave the instrument
switched on, particularly over-night when reduced temperatures may result in condensation.
In standby conditions the sample pump should be switched off'.
1.8.3 The Oxygen Sensor in Use
As oxygen does not absorb infrared (it is diatomic), it's measurement is via a choice of 3
technologies, chemical sensor, paramagnetic sensor and zirconia based Lambda sensor. The
choice of technology is generally made by the application.
Chemical oxygen sensor: This operates in a similar way to a battery in that a voltage is
generated between two plates immersed in electrolyte. The sample gas is passed over a
membrane which allows oxygen molecules to pass through it into the electrolyte, stimulating
the reaction, and resulting in a voltage proportional to the oxygen concentration.
Typically the sensor is calibrated by adjusting for zero reading with nitrogen applied, and for
span using a cylinder containing 20.9% O2, though fresh air can be used for a quick check.
Both span and zero adjustments are made via front panel controls.
The sensor fitted has a long operational life and is very stable. If the output falls (i.e. the gas
reading is low), the sensor should be replaced. Sensor lifetime depends primarily conditions
of use (e.g. average sample oxygen concentration, sample flow rate, temperature), and so
this part is excluded from the instrument warranty. For typical applications, ADC
recommends routine replacement of the sensor every two years as part of the maintenance
programme.
Paramagnetic oxygen sensor: This operates on the principle that oxygen molecules are
paramagnetic in nature and that exposing them to a high magnetic field induces alignment to
the field, creating a movement detectable by a simple infrared sensor reflecting on a mirror.
A very stable and long life sensor with high performance, this sensor offers the best results
for measurement in the range 0-25%. Replacement of the sensor is in excess of 10 years
Calibration of the sensor is identical to procedures used for the chemical oxygen cell
Lambda oxygen sensor: Primarily designed for use in the MGA to measure low levels of
oxygen down to 100ppb levels, the sensor uses a variation on the zirconia oxide ceramic
sensors developed by Nernst. The Lambda sensor and is in general use in motor vehicles.
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Calibration within the MGA is similar to the other oxygen sensors, but this sensor does
require an annual service and calibration outside of the MGA to ensure continued use.
The sensor has a lifetime of around 2-4 years in use is small i
ADC Gas Analysis Ltd or their authorised local agents can supply replacement sensors with
the correct fittings and electrical characteristics. Fitting alternative parts may cause
problems and will invalidate the instrument warranty.
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2. INSTALLATION
2.1 Installation Arrangement
The basic arrangement of the Instrument is a „3U‟ or „6U‟ high, 483mm (19”) chassis for rack
mounting, or alternatively, it may be supplied with a case for bench mounting.
In multigas applications because of restrictions of space a “double” 6U high case may be
used
All power input, output and gas connections are via the rear panel.
Power connection is via a standard three-way IEC power plug. A suitable plug and cable is
supplied.
Gas connection details are indicated in Section 1.5.3, 1.5.4, 2.7
RS232C, analogue and alarm contact outputs are detailed in sections 2.4, 2.5 and 2.6
respectively.
2.2 Location & Ambient Conditions
The location must provide firm support and access to the rear of the instrument when the
instrument is mounted in the normal attitude on its base. When installed in a rack, the use
of runners is recommended.
It is not necessary to force ventilate the enclosure to cool the unit, but free circulation of air
is necessary for accuracy and reliability.
Although it is not necessary to maintain a controlled environment during use, a reasonably
stable ambient temperature gives best results. Sudden changes in temperature will disturb
the IRGA bench(s), causing a shift in readings until the compensation recovers. If a drop in
temperature is expected, it is best to leave the instrument energised (switched 'ON'), to
avoid possible condensation of water in the optical bench. If not being used in this condition,
it is also better to switch off the sample pump as this not only prolongs the life of the pump,
but helps to reduce condensation.
In all cases the ambient conditions must comply with the specifications. High
ambient conditions will affect reliability.
IMPORTANT: The MGA series analysers are not certified for operation in hazardous
environments.
2.3 Power Supply Setting & Connections
2.3.1 Power Supply Setting
The instrument operates from single phase, 90-240 volts nominal AC, at 50 or 60 Hz.
The supply frequency is not critical.
Spare fuses are provided which are 20 X 5 mm ceramic HRC „T‟ (Time Delay) types.
Maximum Power consumption is 120VA.
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2.3.2 Power Supply Connections
The power cable supplied must be connected to a suitable plug or distribution
board as follows:
BROWN - Line or High Voltage
BLUE - Neutral or Low Voltage
GREEN/YELLOW - Earth or Ground
For safety reasons the Earth connection MUST provide a low resistance to Ground.
Further protection is provided by making a direct Earth-Bonded connection to the chassis of
the instrument, via a 4mm screw. This bonding is just below the voltage selector.
The instrument is provided with an ON/OFF switch under the power socket.
WARNING
If the front, top or bottom sections of the enclosure are removed, BEWARE of
HIGH VOLTAGES near the power connector, switch and internal supply.
When REMOVING or REPLACING the enclosure sections ALWAYS disconnect the
mains supply FIRST.
Avoid touching the electronic boards. If these are removed for any reason -
SWITCH OFF the instrument FIRST.
DO NOT HANDLE without ANTI-STATIC precautions being taken.
2.4 Serial I/O (RS232C)
An industry-standard serial port is fitted which allows the analyser to be connected to a wide
range of computer equipment for logging and remote control.
The connector is similar to an „AT‟ style PC serial port allowing the use of standard cables.
The serial port is configured from the front panel – see section 3.7.2. The serial port protocol
is detailed in section 3.7.1.
Serial (RS232C) Port Connections
Pin Name Function
1 - no connection
2 Rx Received data (input)
3 Tx Transmitted data (output)
4 DTR Handshake for Rx (output)
5 Ground 0V (nominally chassis)
6 - no connection
7 RTS „true‟ whenever unit is powered
8 CTS Handshake for Tx (input)
9 - no connection
Notes:
1. DTR is normally „true‟
2. CTS is monitored only when „hardware handshake‟ is selected
3. Screened cables must be used for RS232 connections
In common with all RS232C ports, long cable runs can cause problems with data corruption
and noise. Keep cables as short as practicable – certainly no longer than 30 meters at 9600
baud. Route signal cables well away from power cables, switchgear and other noise sources.
MGA3000 Multi-Gas Analyser Operation Manual Iss. 3.01
21
For long cable runs, and in electrically noisy environments, optical RS232C cable extenders
are recommended. Contact ADC Gas Analysis Ltd. or their local authorised agents for advice.
2.5 Analogue Outputs
Analogue outputs are provided for connection to chart recorders, remote meters, analogue
logging equipment etc. Up to four outputs are available; one for each gas reading.
The outputs are arranged so that the reading shown at the top of the screen is presented on
analogue output 1, the reading on the next line down (if any) is presented on output 2 and
so on. Where there are fewer than four gas readings, unused analogue outputs will be
inactive or not fitted.
The analogue outputs are available via a circular „DIN‟ connector on the rear panel, labelled
„OUTPUTS‟. A suitable connector is provided in the kit with each instrument, and further
supplies are available from ADC Gas Analysis Ltd. or their authorised local agent.
Analogue Output Pin Connections
Pin Function
1 I output 4 sink
2 I output 3 +ve / I output 3 source
3 I output 1 +ve / I output 1 source
4 I output 3 sink
5 I output 2 sink
6 I output 4 +ve / I output 4 source
7 I output 2 +ve / I output 2 source
8 I output 1 sink
shell 0V (connected to chassis)
NOTES:
1. I is used to indicate pin functions when output is set to 4..20mA mode
2. Screened cable should be used for analogue output connections (screen to connector
shell).
Each output is set as standard
4 – 20mA - current mode
All outputs are non-isolated
Optional output cards can be specified to provide isolated mA, voltage and MODBUS RTU
Figure 3 – Analogue Output pin numbers
MGA3000 Multi-Gas Analyser Operation Manual Iss. 3.01
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2.6 Alarm (Trip) Outputs
The alarm outputs are isolated relay contacts which can be set to operate at certain gas
levels, or on sample flow error. Up to five contacts may be available depending on the
specification of the instrument. The number actually available is shown on the trip set-up
screen (see section 3.6.1).
Alarm contact outputs are available via a 15 way “SUB-D 15 F” connector on the rear panel.
A suitable connector is provided in the kit with each instrument, and further supplies are
available from ADC Gas Analysis Ltd. or their authorised local agent.
The connector pin functions are printed on the rear panel adjacent to the connector, and the
pin numbering scheme is shown in Fig 4.
See section 7.3 for specifications.
A nominal 24 Volt (20%) DC supply is available at the
alarm connector which can be used to power larger relays,
sirens, indicator lamps etc. This power source is internally
fused at 1A and the maximum continuous load is 500mA.
The +24V DC supply is referenced to chassis ground.
2.7 Gas Arrangements
2.7.1 The Gas Circuit
The gas connections within the instrument are shown on the gas circuit enclosed with this
manual. The gas circuit is quite specific to a particular instrument and shows how the gas is
routed from the inlets to individual analysis bench(s). Gas connections are via 'entries' that
are located on the rear panel.
All external connections are made with 6.35mm (1/4'') pipe fittings. The type of piping used is
recommended to be either polythene for general use or polytetraflurothalene (PTFE) or
stainless steel for corrosive gases.
All entries are fitted with in-line filters that are intended to stop any foreign matter entering
the instrument as a last resort. Unless the gas is perfectly clean and dry, particulate
filters and / or driers must be fitted externally.
Contact ADC Analysis Ltd. or their authorised local agents for advice.
The requirements for particular gases vary with the application and therefore these and the
gas circuit are specific to the delivered Instrument. Some guidelines follow, but it is the
responsibility of the installer to ensure that all safety and other requirements are met.
The Instrument Specification accompanying the Instrument defines the specific requirements
and this must be referred to during installation.
WARNING
All Gases are potentially toxic and hazardous to health.
All gas lines and connections must be leak-tight. Joints can be checked by
applying water containing some liquid soap and looking for bubbles.
Exhaust lines must be properly vented and arranged to prevent blockage.
Ventilate the enclosure to prevent a build-up of gas in the event of a leak.
Figure 4 - Alarm connector pin numbers numbering
MGA3000 Multi-Gas Analyser Operation Manual Iss. 3.01
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2.7.2 The Sample Gas
The gas to be measured is the 'sample gas' labelled 'GAS IN'. After passing through the gas
circuit the measurement gases are exhausted at the entry labelled 'GAS OUT'. The analyser
is designed to receive sample gas at nominally atmospheric pressure, using the internal
sample pump to control the flow. Alternatively external pumps may be used
The Sample Gas supplied to the Instrument must be relatively clean, cool and of low
moisture content. Samples containing dust or particulates must be filtered externally and the
filters serviced at regular intervals.
Hot Samples with high moisture content should be passed through a water trap or dessicator
after cooling.
To prevent the possibility of condensation in the Instrument if the Instrument is not in
continuous use, it is recommended that it is left Switched on with the Sample Pump Switched
off.
Samples may contain other gases which „interfere‟ with the gas being measured.
The extent to which known interferents can affect the measurement are defined in the
Instrument Specification.
Sample gas pipes shall be inert to and shall not contaminate the gas.
The response time for a change in concentration will be affected by the sample flow rate.
Instrument response times are normally quoted for the recommended 500ml min-1 flow rate,
ignoring the effect of sample pipe volume. Lower flow rates will increase the response time,
as will the volume of the sample piping. Higher flow rates will reduce the response time, but
excessive flow will pressurise the instrument which may cause damage or measurement
errors.
If it is necessary to draw higher flows than recommended (e.g. due to long sample gas lines),
it will be necessary to provide some means of bypassing the excess flow to exhaust.
2.7.3 The Span Gas
The Span Gas is used for calibration and is a known concentration of the measured gas -
usually between 10% and 80% of the full-scale range of the Instrument. The gas is usually
obtained specially mixed in a pressurised cylinder and this must be fitted with a 2-stage
pressure regulator, with an output pressure indication of 0 - 0.3 Bar (0-5psig).
The Regulator should be set to give a nominal output pressure of 0.2 Bar (3psig). This will
usually give a suitable gas flow during a span operation (i.e. flow indicator approximately
mid-position). If necessary, a small adjustment to the pressure will provide correct flow.
WARNING – Application of gas pressures above 0.3 Bar / 5 psig will damage the
instrument.
2.7.4 The Zero Gas
The zero gas is used to check/set the reading from the optical benches in the zero
concentration condition. Dry nitrogen is the preferred zero gas as it is cheap and readily
available.
The zero gas must not contain any significant traces of the gas measured or interferents. For
all types of instruments and gases measured, nitrogen (from a cylinder) is usually specified.
For some gases however, fresh air may be used (for example on high concentration CO and
MGA3000 Multi-Gas Analyser Operation Manual Iss. 3.01
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CO2 Instruments). When fresh air is used, it shall be drawn from 'outside‟ air and away from
any possible contamination from such as Exhaust Ducts, Chimneys, etc.
In most respects fresh air should be treated in the same way as the sample gas with regard
to filtering, moisture content etc. See span gas, section 2.7.3.
2.7.5 The Purge/bypass Gas
For some instruments, multirange and oxygen separate inlets ports and outlets are provided
where fresh air is drawn into the analyser to allow unused gas cells to be purged of gases
2.7.6 The Exhaust Gas
Exhaust gas is the sample (or zero/span) gas that has passed through the analyser.
For hazardous gases (high concentrations, flammable or poisonous), exhaust gas must be
carefully routed to a safe venting point.
It is important to minimise „back pressure‟ at the GAS OUT port, as this will affect readings
and reduce the efficiency of the sample pump. Where long runs of pipe are necessary, larger
bore pipe should be used via a suitable adapter. Where the exhaust pipe is connected to a
forced air extraction duct, make sure that any suction is minimal.
2.7.7 Gas Pump(s)
Gas pumps fitted in the instrument are of the vibrating diaphragm type and are capable of up
to 1.0 I/min1 under pressures normally encountered.
The sample pump operates at fixed speed and at a flow rate of nominally 500 ml/m1n1.
If it should be necessary to adjust the flow, it can be set using the potentiometer VR2 on the
power supply board and / or the throttle (when fitted).
The internal sample pump is operated via the front panel 'PUMP' menu button.
Certain instrument configurations may be fitted with a second internal pump which is used to
circulate purge gas. This pump would be set to run continuously at a factory set rate.
2.8 Use of Chemicals (certain models only)
Certain instruments use chemicals to remove (or strip) certain gases from the air for zero
adjustment, or to purge the optics to prevent ambient air from affecting readings. These
chemicals must be replaced regularly to ensure efficient operation and hence good accuracy.
The chemicals are contained in glass „columns‟ which are accessible from the front of the
instrument to aid inspection and refilling.
The chemicals that may be used are listed below under the gas application.
2.8.1 Water Vapour
An indicating form of calcium sulphate (CaSO4) known as 'DRIERITE' is normally supplied
with new instruments and replacement supplies are available from ADC Gas Analysis Ltd or
their local authorised agents. In use, drierite changes from blue to pink as it becomes
exhausted, making it obvious when the container should be refilled with fresh chemical.
Drierite can be recovered by drying.
MGA3000 Multi-Gas Analyser Operation Manual Iss. 3.01
25
„Silica gel‟ is a good indicating drier, but can „hang on‟ to some gases, especially C02, giving
false readings, and is not generally recommended.
2.8.2 Carbon Dioxide
To remove C02, usually in a C02 Instrument, indicating „soda lime‟ is used. Soda lime
consists of about 80% calcium hydroxide ((Ca(0H)2)), 4% sodium hydroxide (NaOH) and
0.2% indicator (green to brown).
In use, soda lime changes from green to brown and must be changed when green is no
longer visible. It is not recoverable. Replacement supplies are available from ADC Gas
Analysis Ltd or their local authorised agents.
Other chemicals may produce corrosive by-products which can damage the instrument.
2.8.3 Precautions
Any chemical intended for use in the instrument is provided with it in a separate container,
labelled with international identification labels. Under normal use, the quantity supplied will
last for about 6 months to a year. Replacements can be obtained from ADC Gas Analysis Ltd
who will also advise on the use of chemicals obtainable by the User.
When handling chemicals, refer to the „Safety Letter‟ enclosed in the manual for precautions
against possible health risk. For all chemicals, avoid skin and eye contact and do not taste or
swallow them.
2.9 Pre-operation Checks
Before connection power to the instrument, check:
1. That gas connections are leak free
2. That the exhaust gas venting arrangements are safe for the gases in the sample
3. That the instrument is properly grounded (earthed).
2.10 General Advice
2.10.1 Use of Gas Cylinders
Before use, Gas Cylinders must be checked to ensure that -
the cylinders are securely located.
the cylinders are fitted with a two-stage regulator.
the cylinders contain the correct gas mixture for use.
the cylinders are connected to the correct „entry‟ on the Instrument.
the cylinder's Output Pressure regulator is 'OFF'.
During use, check -
• the Instrument is 'ON'.
• the Sample Pump is 'ON'.
• the Output Pressure regulator is set for 0.2 Bar.
After use, check -
• the Output Pressure regulator is turned 'OFF'.
MGA3000 Multi-Gas Analyser Operation Manual Iss. 3.01
26
• the cylinder tap is turned 'OFF'.
• if the Instrument is in „Standby‟, turn 'OFF' the Sample Pump.
Following a cylinder change, it is advisable to initiate a Span or Zero cycle a few minutes
after the supply is re-connected.
2.10.2 Gas Leaks
All external-piping connections must be checked for gas leaks, to ensure that no gases are
leaking to the local area (which may be a health hazard), and that no uncontrolled air or gas
is drawn into the Instrument (and so affect the measurement).
Applying water containing a mild soap solution can check connections under pressure. Do not
increase the pressure to check for leaks (or for any other reason), since this may damage the
Instrument.
Connections of pipes under nominally ambient pressure, such as the sample piping, are
difficult to check for leaks, but can be checked for tightness.
2.10.3 Exhausting & Ventilation
Because any gas is potentially toxic, and, some may be inflammable, the gas must be
exhausted to where it will be rapidly dispersed. For the same reasons, the Instrument and
its environment including the location of gas cylinders must be properly ventilated to
minimise the dangers of gas leaks.
If Span cylinders contain hazardous or inflammable gases, they must carry suitable warning
labels, and if inflammable, must be located in a suitable „Inflammable Store‟ when in use or
in storage.
In all cases the local safety regulations must be consulted and followed.
MGA3000 Multi-Gas Analyser Operation Manual Iss. 3.01
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3. SETTING UP
3.1 Preview
This section describes the settings available from the front panel. Factory settings have been
chosen to suit the general application of the instrument, or in accordance with the particular
instructions specified previously by the user.
3.2 On Power Up
IMPORTANT: Before operating the Instrument, ensure all the relevant installation
checks have been carried out [refer to Section 2.9], and that if a filter column is
fitted, it is properly charged with the chemical supplied.
Immediately after power is applied, the display presents a screen for 10 seconds. This page
contains the software version number.
If the logo does not appear on the screen
within 20 seconds of applying power, try
adjusting the „LCD‟ control, using a 2mm flat
bladed screwdriver through the labelled hole in
the rear panel.
The next screen is the main display, which will show the measured value(s), units and the
Gas type, sample flow status and key functions.
The measured value is initially replaced with a
symbol of a thermometer until the instrument
has warmed up.
Pressing the key labelled „Set Up‟ displays a
second screen showing the gas(s) measured
together with the range and units.
Pressing „More‟ allows other gas measurement s present to be shown
3.3 Zero & Span Operations.
Before precise gas readings can be obtained, the analyser must be adjusted so that it reads
zero when there is no trace of the measured gas present, then, when a known concentration
of the gas is applied, the reading is adjusted to agree with this concentration.
These adjustments are known as „zero‟ and „span‟ respectively.
The gases used for zero and span adjustment are supplied through the inlets at the back of
the instrument (see section 2.7), and electrically operated valves are used to route the
HCL
NOX
CO
SO2
Range
Calib
Set Up
Stp.Pump
MGA3000 Multi-Gas Analyser Operation Manual Iss. 3.01
28
Figure 7 - screen contrast adjustment
Figure 5 – Set-up Automatic Zero
appropriate gas in place of the sample automatically when zero or span adjustment is
selected using the front panel controls.
'How often' to Zero or Span varies with each instrument. The interval required depends on
how much re-adjustment is being carried out: this can be established by noting the
discrepancy of the displayed value prior to resetting.
If the discrepancy is less than 0.5% of full scale, the intervals can be increased, or if this is
not accurate enough, decreased. Generally Zeroing is required more often than Spanning, so
that typically a daily Zero, with weekly Span is
adequate.
The instrument can be set to automatically adjust
zero or span on a periodic basis.
The period can be set from 1 hour to 250 hours for
zero and 1-99 zeros between spans.
The normal operating layout is shown in Fig 5
See section 4 for details.
3.4 Display & Keypad
3.4.1 Display
The normal operating layout is shown in Fig 8, but
note that this is an example; the gases shown will
vary with the specification ordered.
On the left of the screen are the gas names,
followed by the current reading(s). A thermometer
symbol indicates that the analysis bench is warming
up – readings will be shown when warm-up is
completed.
On the right, adjacent to the four „function‟ keys, are the key labels.
These describe the functions of the keys at any time, and the labels change as different
options are selected.
Between the gas readings and the function key labels, is the sample flow indicator, which is
designed to mimic a float flowmeter. Normally, the flow, as indicated by the „float‟, should be
around the centre of the indicator. If the float is in a shaded region, the flow is too high or
low and a warning triangle is shown.(Flow display can be optional with related flow switch
range(currently, 200 ㎖/min is installed))
Flow fail and alarm trips are indicate at the bottom
of the display.
The LCD display is affected by ambient temperature
and viewing angle. A contrast control is provided to
adjust the display to give the best contrast under all
viewing conditions.
To adjust the contrast, Select the following menu
functions: Set Up , Display
The contrast screen is displayed. Use the lighter
and darker controls to get the best display. The
bar shows the amount of contrast adjustment. If it is not possible to get good contrast within
Figure 6 - Example Main Screen (4 gas)
HCL
NOX
CO
SO2
PP
M
PP
M
PP
M
PP
M
2.2
16.2
21.2
18.1
Range
Calib
Set Up
Stp.Pump
MGA3000 Multi-Gas Analyser Operation Manual Iss. 3.01
29
Figure 8 – Main Overview
HCL
NOX
CO
SO2
PP
M
PP
M
PP
M
PP
M
2.2
16.2
21.2
18.1
Range
Calib
Set Up
Stp.Pump
the range of the bar, press the „Default‟ key, then, using a 2mm flat-bladed screwdriver,
adjust the „LCD‟ control through the labelled hole in the back panel for best display. Note
that the rear panel control has a wide range and the display will not be visible for extreme
settings.
3.4.2 Function Keys
The instrument is operated using the four function keys to the right of the display screen.
The keys are labelled on the display, allowing the functions of the keys to change dynamically
as options are selected.
Range
Measuring gas is the range selectable
Manual and Automatic range
Calib
Zero & Span adjustment
Auto Zero & Span setting of the time
period
Manual calibration & Auto calibration
Set Up
Sample flow is adjustment
Setting by Trips(Alarm), Key click,
Warming Beep, Decimal point, Serial port, etc..
Stp.Pump
Sample Pump Start /Stop
▣ Function key button by select “Push”
MGA3000 Multi-Gas Analyser Operation Manual Iss. 3.01
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Figure 8 – Menu tree
3.4.3 Menu tree
MGA3000 Multi-Gas Analyser Operation Manual Iss. 3.01
31
Fig. 8 shows the menu „tree‟, starting from the main screen showing the sample gas
readings.
Sub-menus provide routes to more detailed functions, until the operator is required to 'DO'
an action. At this point, the display will present instructions, or more information, appropriate
to the action required.
For example, pressing the function key 'Zero adj' on the main menu, presents a Sub-menu
with the function keys on the right hand side of the display and instructions on the bottom of
the screen.
3.5 Analogue (Chart) Outputs
An analogue output is provided for each gas measured (up to 4 channels). The outputs are
available from a circular DIN type connector on the rear panel. Outputs are set for 4-20mA
at the factory, a operator interface in the menu is included to allow adjustment where
required, and test at See section.
The outputs are arranged so that the gas shown on the top line of the screen is presented on
analogue output 1. The gas shown on the second line of the screen (if any) is presented on
output 2 and so on.
Analogue output scaling is fixed and corresponds to the full scale measurement range of the
associated gas. Analogue outputs do not indicate negative or over-range conditions.
3.6 Alarm (Trip) Outputs
The MGA analyser features up to five electrically isolated alarm contact outputs. The alarms
can be set up individually from the front panel to indicate gas readings above or below a set
value, inside or outside a set range, or to indicate sample error.
The number of trip contacts fitted may vary depending on the specification ordered.
For connection information, see section 2.6.
3.6.1 Setting Alarm Outputs
The alarm outputs are not set at the factory.
To set or check the alarm settings from the main
screen, press the „Trips‟ function key. The screen
will list the settings for each trip fitted. If no alarms
are fitted, a warning message will appear before
returning you to the main screen.
Use the and keys to highlight a trip then press:
„Test‟ To temporarily set a trip to the alarm state –
allowing connected equipment to be tested.
„Change‟. To modify settings for the selected trip. The screen will display the selected trip,
and the function keys now offer items to change. From this screen use:
„Gas‟ to select the gas for which this trip is active, or alternatively select „not set‟ (trip not
used) or „flow error‟ (active if sample flow out of range).
Figure 9 - Trip settings screen
MGA3000 Multi-Gas Analyser Operation Manual Iss. 3.01
32
„Lo point‟ to set a gas value below which the trip is active. If there is no reading shown
under this column on the display, or if the „Off‟ key is used when setting the low point, this
trip will not respond to low readings.
„Hi point‟ to set a gas value above which the trip is
active. If there is no reading shown under this
column on the display, or if the „Off‟ key is used
when setting the low point, this trip will not respond
to high readings.
Note: setting both high and low trip points
will give a range indication.
„Contacts‟ to swap between normally-closed („n/c‟)
and normally-open („n/o‟) contact modes to suit externally connected equipment. In
normally-closed mode, the trip is fail safe in that power failure, disconnection or trip
becoming active will all open the circuit, generating the alarm.
„Done‟ to save any changes made and return to the previous screen.
Repeat the settings above for each trip to be set.
3.7 RS232C Serial Port
A serial port is available on the rear panel (labelled „RS232C‟), to which a PC, VDU or other
computer equipment can be connected. The port provides a way of monitoring the readings
remotely, and triggering auto-zero.
For connection information see section 2.4.
3.7.1 Protocol
Please refer to the Section 9.
3.7.2 Serial Port Settings
The serial port is configured from the front panel. To check or change the serial port
settings, select:
Set Up , Ser. Port
From the main screen menu.
The screen will show current settings.
Press the „Baud‟ key to cycle through the available
port speed options
Press the „Handshk.‟ key to cycle through the
available flow control / handshaking options.
The „Done‟ key will store any changes before returning
to the previous screen.
Note that the data format is fixed at 8 bit data, no parity, 1 stop bit.
Figure 10 - Setting up a trip
Figure 11 – Serial port setting
MGA3000 Multi-Gas Analyser Operation Manual Iss. 3.01
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3.8 Measurement
The gas ranges, display format and units of measurement are factory set to order, and no
changes are possible. If changes to ranges or gases are required, contact ADC (Sales &
Service) Ltd. or their local authorised agents for a quotation.
Units of measurement are normally „by volume‟ or „ppm‟ though other options are possible to
order (e.g. mg m-1).
The display uses up to four digits, with values up to 3 decimal places, depending on range,
gas etc.
The symbols shown in place of the readings are as follows:
Over-range – the reading is too high. Normally this indicates a gas concentration that
is above the measuring range.
Under-range – the reading is too low. Normally, zero adjustment will correct the
problem.
Warming up – the associated analysis bench is stabilising.
readings will be shown when warm-up is completed.
The measured value is initially replaced with a symbol of a thermometer until the instrument
has warmed up.
HCL
NOX
CO
SO2
Range
Calib
Set Up
Stp.Pump
Figure 12 – Initialize Screen
MGA3000 Multi-Gas Analyser Operation Manual Iss. 3.01
34
4. CALIBRATION
Gas readings made using IRGA optical benches are relative rather than absolute.
Before precise gas readings can be obtained, the analyser must be adjusted so that it reads
zero when there is no trace of the measured gas present, then, when a known concentration
of the gas is applied, the reading is adjusted to agree with this concentration.
These adjustments are known as „zero‟ and „span‟ respectively.
Routine calibration is important, not only to verify measuring accuracy, but also to spot
changes over time that may indicate problems.
Note: because the instructions will vary slightly from gas to gas, the instructions given here
are fairly general. ADC Gas Analysis Ltd. or their authorised local agent will be pleased to
answer any questions.
4.1 Initial Checks
It is assumed that the instrument is correctly installed and all gas connections are correctly
made – if not, refer to section 2.
Before operating the Instrument, ensure all the relevant installation checks have
been carried out [refer to Section 2.9], and that if a filter column is fitted, it is
properly charged with the chemical supplied.
As one of the first operations concerns Zeroing and Spanning the Instrument, ensure that
external Zero and Span Gas supplies are available for connection to the Instrument.
If gas cylinders are used, check the Pressure Regulators are set correctly.
Make sure that the Power Settings [on the Rear Panel] are correct for the supply used [refer
to Section 2.3]
4.1.1 Warm Up
If previously removed for any reason, re-fit and secure the enclosure's front or top covers to
the Instrument. The covers are necessary to ensure that the internal temperature stabilises.
Switch on the Instrument via the Rear Panel mounted Power ON/OFF switch, and allow the
instrument about 30 to 60 minutes to warm up.
Until the instrument has reached operating temperature the display will indicate a symbol
which represents a thermometer. This symbol will be replaced by the gas measurement
when the correct temperature has been achieved.
4.2 Zero Adjustment
Before a zero adjustment is made ensure that the gas cylinder is connected and
that the correct pressure is set.
See section 2.7.4.
MGA3000 Multi-Gas Analyser Operation Manual Iss. 3.01
35
Figure 13 - Zero screen (Multi gas model)
4.2.1 Manual Zero
1. Select 'Zero Adj. ' on main menu, which will
display the zero screen and apply zero gas to
the analyser bench(s).
2. Verify that the flow meter shows adequate
flow – zero adjustment cannot be made if the
flow is incorrect. If necessary, make small
adjustments to zero gas pressure to correct
the flow.
3. Wait for the gas reading to stabilise,
allowing any error to be noted.
4. If the reading(s) are satisfactory, press „< Main‟ to return to the main screen without
making changes. – or ->
5. When the readings have stabilised, select the key labelled with the gas type you wish to
zero.
6. The microprocessor will then reset the reading to zero. If the change is to great and the
processor is unable to reset the zero, a warning message will appear on the screen.
Depending on the bench type, the message will either warn of failure, or offer to set
„coarse zero‟.
7. Before selecting to perform coarse zero adjustment, double check that the zero gas is
correct – coarse zero cannot be cancelled and may take a few minutes.
4.2.2 Auto Zero
MGA series analysers can set zero automatically at user set intervals, or by command from
the RS232 port. Automatic zero does not require
user intervention, but it will „freeze‟ the analogue
output voltages temporarily.
Auto zero is set by selecting the following from the
main screen:
Set Up , Auto Z.
The screen shows the current setting, and, if a time
period is set, the time until the next zero
adjustment.
The interval for auto zero can be set in 1 steps selecting the + or - key until the required
time is set. Press „Off‟ to disable auto zero, and „< Back‟ to save settings and return to the
previous screen.
When an Auto Zero takes place the analyser will go through the same procedure as for a
manual Zero, but the processor will automatically reset the gas reading to Zero.
Auto zero will attempt adjustment for all gases, but will not initiate a coarse zero adjustment
if the standard zero fails.
When using Auto Zero the zero gas cylinder must be connected at all times
4.3 Span Adjustment
Before a Span adjustment is made ensure that the gas cylinder is connected and
that the correct pressure is set. See section 2.7.3.
Figure 14 - Auto zero set-up screen.
Zero Adj.
Span Adj.
Aut. Span
Aut. Zero
Main
HCL
NOX
CO
SO2
PP
M
PP
M
PP
M
PP
M
0.0
Zero gas selected ? purging
0.0
0.0 0.0
MGA3000 Multi-Gas Analyser Operation Manual Iss. 3.01
36
Before a Span adjustment is made ensure that the analyser is set to the higher or
maximum range for multirange analysers.
It is recommended that zero adjustment is done immediately prior to adjusting span.
For multi-gas analysers, it is convenient if the span gas used is a mixture containing an
accurately known concentration for each of the gases measured. If this is not practicable,
then the span process must be repeated for each gas in turn, using the appropriate span gas.
4.3.1 Setting Span
Select 'Span Adj.' on the main menu. The span screen will be displayed, and the span gas
will be connected to the analyser(s). The readings will change to reflect the span gas.
Verify that the flow meter shows adequate flow – span adjustment cannot be made if the
flow is incorrect. If necessary, make small adjustments to span gas pressure to correct the
flow.
Wait for the gas reading(s) to stabilise.
If the readings are satisfactory, press „< Main‟ to return to the main screen without making
changes. – or ->
Press the key labelled with the appropriate gas. The
display will ask you to set the correct gas value. The
value offered is that last used, but if necessary use
the Gas + and Gas - keys to set a value that agrees
closely with the span gas concentration.
Press „Set Span‟. The microprocessor will then
reset the reading to the value entered. If the change
is to great and the processor is unable to reset the
span, a warning message will appear on the screen.
If the span adjustment fails, carefully check the span gas cylinder. If possible, verify the gas
concentration on a second analyser, or try another bottle of span gas. If the span fails and
the span gas is correct, contact ADC Gas Analysis Ltd., or their local authorised
agents for service.
4.3.2 Auto Span
MGA series analysers can set span automatically at user set intervals, or by command from
the RS232 port. Automatic span does not require user intervention, but it will „freeze‟ the
analogue output voltages temporarily. Users may choose the gases to be included in the
autospan operation
Auto span is set by selecting the following from the
main screen:
Set Up , Auto S.
The screen shows the current setting, and, if a time
period is set, calculated by number of zero‟s entered,
the time until the next span adjustment.
The interval for auto span can be set in 1 steps
Figure 16 - Auto span set-up screen.
Figure 15 – Setting the span gas
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selecting the + or - key until the required interval is set. Press „Off‟ to disable auto span, and
„< Back‟ to save settings and return to the previous screen.
When an Auto Span takes place the analyser will go through the same procedure as for a
manual span, but the processor will automatically reset the gas reading to the entered span
gas values. Auto span will attempt adjustment for all gases.
When using Auto Span the span gas cylinder must be connected at all times
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5. MAINTENANCE
5.1 Routine Checks
Problems with the Instrument can be avoided if the installation is maintained regularly,
especially with regard to parts used to pre-condition or route the various gases, and in
particular the sample gas.
The User should be aware of any constituents of the gas that may directly or indirectly affect
the optical components within the instrument as described in Section 2.7.2.
If Water Traps and/or Particulate (dust) Filters are included in the installation these must be
periodically inspected and maintained to avoid overflows or blockage.
5.1.1 Water Vapour
If, during the initial installation of the Instrument, the presence of high water vapour content
was not expected (and therefore means of trapping it was not included) signs of it should be
looked for during routine maintenance, particularly during the first few weeks of operation.
If transparent piping was used, water can often be seen in droplets on the inside walls or
collecting at a low point in the piping arrangement. With opaque or steel pipes, disconnect
them at a low point to see if water drips out.
If signs of water are found, it may eventually block the pipes or result in amounts being
drawn into the instrument which may affect the pumps, solenoids etc., as well as the optics.
In this case, it is recommended that some form of Water Trap be fitted, such that the
contents can be easily seen and regularly inspected.
If the Sample does contain water vapour, leave the Instrument switched on if it is not in use,
and with the Sample Pump off. This will help to prevent condensation within the instrument.
A service visit is advisable in cases of water ingress, so that the optics can be cleaned. Dirty
optics will reduce performance.
5.1.2 Dust
Long term problems may occur if dust is in the sample. Usually this cannot be „seen‟, but
over a period of time it can build up and affect all parts of the gas path. Dust may also block
the particulate filters fitted in the inlets of the Instrument and may therefore result in a
blockage or a reduction in flow.
As part of the maintenance routine, inspect the Inlet Filters for signs of dust. If there is any
sign of dust, the sample line must be fitted with a suitable filter (down to 1O microns) and
the filter elements regularly replaced.
Where dust has penetrated the instrument, arrange for a service visit so that the optics can
be cleaned and full performance restored.
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5.2 Instrument Checks
The instrument requires little maintenance, other than the filter column (if fitted), source
block purge (if fitted), sample flow adjustment (if necessary), and zero and span adjustment
(see section 4).
5.2.1 Source Block Purge (when fitted)
Certain instruments fitted with the „SB‟ type IRGA bench have a CO2 trap to remove traces of
the gas from the source block. The trap is a glass jar which protrudes through the front
panel of the instrument, filled with indicating soda lime (see section 2.8.2). The colour of the
soda lime should be checked regularly, and the contents replaced when only the very end of
the jar remains green. The jar is removed by unscrewing.
When replacing or handling chemicals, avoid physical contact and wash hands
afterwards.
Dispose of chemicals carefully and in accordance with any local Health & Safety
requirements.
5.2.2 Filter Column (when fitted)
If a Filter Column is fitted, regularly check the condition of the chemical it contains. The
characteristic to look for when the chemical is exhausted depends on that used and is
described in Section 2.8.
Replace the chemical before it is completely exhausted to avoid subsequent „hang-up‟. If it is
used in an exhausted state it may cause unstable operation of the Instrument.
When replacing or handling chemicals, avoid physical contact and wash hands
afterwards.
Dispose of chemicals carefully and in accordance with any local Health & Safety
requirements.
5.2.3 Sample Flow
Once set, sample flow should not require adjustment unless it moves near the shaded areas
on the flow meter. Before adjusting flow internally, check sample and exhaust piping for
obstruction, state of filters etc.
If the flow continues to fall off over a period of time, it may indicate that the lines are
becoming blocked, as indicated in the previous section.
5.2.4 Throttles
The sample and zero gas flows are normally set in the instrument with external throttles, as
indicated in the Gas Circuit. These paths can also become affected by blockages and they (or
some other reason) may require some re-adjustment.
Readjustment is not a routine procedure – always check span and zero gas bottles, regulator
pressures etc. before attempting adjustment.
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6. OPTICAL BENCH DESCRIPTIONS
6.1 Introduction
This section describes the basic construction and operation of the various types of bench that
may be fitted in an instrument. All the infrared types rely on a characteristic of heteroatomic
gases to absorb energy at specific wavelengths in the infrared spectrum, and, follow the
operating principles described in Section 1.8.1.
Each bench type makes use of a different technique. To recommend a type of bench best
suited to the requirements will generally relate to the type of gas measured and/or the
accuracy and sensitivity of measurement.
6.2 GC Bench
The GC (Gas Correlation) infrared bench is a non-dispersive single beam analyser in which
the gas to be measured is passed through an optical cell continuously. Although the
instrument output is in terms of gas concentration, this type of analyser operates as a
comparator. That is, its output is not absolute, but is established by standardising with a
known gas mixture at a point on the calibrated scale. See section 4.
A typical GC Bench layout is shown in Fig. 18. This reflects a „single‟ analysis cell. Variations
on this will be on the length of cell or the number of cells.
The length of the cell is dependent on the concentration of the sample measured and may
vary from 1mm (at very high concentration) up to about 250mm (at low concentration).
Motor
Sensor Filter Wheel
Source
Lens
Optical Filter
Window Window
Gas Entries Lens
Analysis Cell
Detector
Figure 17 - The Gas Correlation optical bench
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Infrared (heat) radiation from a small source is directed through a rotating filter wheel, a
collimating lens, an optical (Thin-Film) filter, the sample cell, a focussing lens and on to a
solid state detector. The wheel is rotated at 1100 RPM, to give a modulation frequency of
18.3 Hz.
Each cell element is sealed at both ends by a window that does not optically interfere with
the radiation.
The heart of the analyser is the gas filter wheel, which contains a sealed sample of gas of the
type to be measured, and a non-absorbing gas. As the wheel rotates it provides a ratio of
sample and reference signals, in a sequence detected by a wheel position sensor. The ratio
signals, together with the selective transmission of the optical filter, sensitises the analyser to
respond to that region of the infrared spectrum corresponding to the measured gas in the
sample.
When the gas to be measured enters the analysis cell, it absorbs some radiation, and alters
the ratio of the sample and reference signals. It is this change in energy level that is
amplified to give the output signal.
The optical path between the source and the first cell window, and between the last window
and the detector, will normally contain room air, or a gas from which any interfering gases
have been stripped. This air is referred to as „Purge‟ air, and if a chemical stripper is used, it
will be shown on the gas circuit. As Purge air has the properties required for the Zero Gas, it
may be used as such.
Whilst the bench can be stripped down to individual parts and parts replaced, this process will
require re-calibration of the bench and possibly some re-adjustments in the Pre-amplifier
and/or amplifier associated with the detector. Since this requires special training and
equipment, the User should not undertake re-calibration unless such training and equipment
has been approved.
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7. ELECTRICAL SPECIFICATIONS
For specifications relating to gas measurements, refer to the Certificate of Conformity.
7.1 Power Supply
Voltage: 90-240V AC
Frequency: 47 – 63Hz
Maximum Power Consumption: 120VA
7.2 Analogue Outputs
Outputs are not isolated.
7.2.1 Set for current output
Output at zero gas: 4mA 1%
Output at full scale: 20mA 1%
Source resistance: > 1M
Maximum loop voltage: 25V
Voltage drop (at 20mA) 0.5V maximum
Current output sink is connected to chassis (nominally ground).
7.3 Alarm (Trip) Contacts
Contact rating: 1A (non inductive)
Voltage rating: 30V DC / AC peak
Max. Voltage with respect to chassis: 30V DC / AC peak
Auxiliary 24V output: 24V DC 20% at 500mA maximum.
Auxiliary supply has negative rail connected to chassis.
7.4 Serial (RS 232) Port
The port signal levels correspond nominally to RS232C specifications, however the output is
approximately 9V into 7k.
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8. SPARE PARTS
The following table lists some of the more common spare parts. ADC (Spares & Service)
Limited provided total parts support and can quote for any item not listed – just contact us or
our authorised local agent.
Description ADC Part Number
MGA 3000 series Operation Manual MGA-MANUAL
MGA 3000 series Technical Manual MGA-TECMAN
Inlet filter FIL-131/A
In line filter (flowmeter protection) 630-508
Infrared Source (GC bench) after Serial No. 3175 MGA-021
Shutter Motor (GC bench) MGA-R-017
Sample Pump PVU-024
Sample Pump Repair Kit 676-456
Fuse 5x20mm, 1A T 022-256
Fuse 5x20mm, 1A F (aux 24V output) 022-556
Fuse 5x20mm, 500mA F (analogue output) 022-656
Connector for the alarm output, 14 way MGA-B-040
Connector for the analogue output, circular 8 way MGA-B-041
Trimming tool, long 867-056
Mains lead assembly, with UK plug, 5A fused. 052-661
Always quote the Serial Number and Model Number in any communications
requiring spares or after sales support.
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9. „AK‟ REMOTE CONTROL PROTOCOL
9.1 Introduction
The MGA 300 has extensive remote control functionality using a variant of the widely used
„AK‟ protocol.
This document details the commands, allowing full remote control and monitoring of the
analyser.
Before starting, ensure that the serial port speed, handshake mode and analyser address are
set as required to match the AK host, using the „Serial‟ option from the „Set Up‟ menu.
9.2 Protocol Overview
Commands are sent to the analyser as AK „packets‟, which consist of the following parts:
Start code
Address character
Command name
Parameters appropriate to the command, as and when required
End code
Note: spaces are not allowed between the start code, address and command.
A typical command might look as follows: <S>1SEGA 0 1 0.768<E>
Note: In the examples shown, text show in Courier font represents literal characters (i.e.
what you would see if you printed a command), and <S>, <E> represent individual special codes, which are not visible ASCII characters. Any space characters are shown explicitly in the examples. Optional parameters are show in [square brackets].
In this example, the parts are as follows:
<S> Start code, a single STX character (2 hex, or ^B)
1 Address, a single digit between 0 and 9, or a „*‟
SEGA Command name.
For the MGA 3000 all commands have four capital letters.
(one or more spaces)
0 Parameters (3 in this example) 1 These are specific to the SEGA command
0.768 Each parameter is separated by a one or more spaces
<E> End code, a single ETX character (3 hex, or ^C)
The command packet is processed on receipt of the end
code.
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9.3 Address
The address character is used to distinguish different pieces of equipment. The MGA will only
respond to a command if the address digit in the command matches the address set in the
analyser (in the serial port set up screen). If the command address is „*‟ however, the MGA
will always respond.
9.4 Commands and Parameters
The MGA will respond to the commands detailed later. Zero, one or two parameters will be
expected, depending on the command.
For example, the command SREM (set remote control mode) requires no parameters, while
SEGA (set span gas concentration) requires three (channel, range, span gas). In general,
the MGA analyser ignores unexpected parameters.
All commands recognised by the MGA analyser for remote control use consist of four upper
case letters. Case is important.
9.5 Response To Commands
After the analyser receives and processes a command, it sends a reply „packet‟ using a
similar format. Here is an example:
<S>1GRAN 0 77 3000 2.06<E>
<S> <E> Are the start and end codes as before.
1 The analyser address, as set on the serial set up screen.
GRAN An „echo‟ of the command sent.
This will be ???? if the command was not recognised.
0 Status code, a single hex digit, containing status flags.
See below.
77 3000 Returned parameters (if any) appropriate to the command.
etc.
Certain commands require that the analyser is set for „remote control‟ mode, or cannot be
used while calibration is in progress, for example. If a command is inappropriate or badly
formed, it will be ignored, and the reply will contain a fault code in place of any parameters.
Here is an example:
The error indications are as follows:
SE Syntax error; bad, missing or illegal parameter values.
NF Not fitted; command addresses a channel, range or
option that is not fitted. CAL In calibration; this command is not allowed while
calibrating. WMUP In warm-up; this command is not allowed while the analyser
Is warming up. SMAN Manual; this command is not allowed while analyser is
in local control mode. Use the SMAN command first.
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Do not confuse ‘SMAN’ when used as an error indication, with a response to a valid SMAN command. Error indications are parameters, and appear after the command echo.
9.5.1 Status Codes
The status code digit indicates certain error conditions. It consists of four flag bits summed
into a single hexadecimal digit as follows:
Bit Weight Indication when set
0 1 One or more analyser channels indicate failure
1 2 Sample flow error (too high or low)
2 4 Last zero attempt failed
3 8 Last span attempt failed
Since it is possible for more than one error to be indicated, the code displayed is the sum of
the weights of the active indications.
Examples:
Error code digit Error(s)
2 Sample flow error
A Sample flow error & last span failed
B Last zero failed & last span failed
Both zero and span fail indications remain set until a successful zero/span has been
completed, or the analyser is reset.
The flow error indication is set whenever a warning triangle would be shown under the flow
meter on the analyser display.
Analyser failure indication normally indicates that service attention is required.
9.6 Command descriptions
9.6.1 Interrogation Commands
Used to determine the analyser type and the gases and ranges fitted. These commands can
be sent at any time; remote control mode is not a prerequisite.
9.6.2 Show model and version information
Command: GRAN
Parameters: none
Data returned: <model> <version>
Where: <model> is always 77 3000
<version> is firmware version, and of the form x.yy
Example reply: <S>1GRAN 0 77 3000 2.06<E>
9.6.3 Show range information
Returns information about a specific channel and range. Poll all possible channel/ranges to
get full details for the analyser.
Command: GRRD
Parameters: <channel> <range>
Where: <channel> is an integer 1..4 selecting possible channel
(which equates to a specific gas)
<range> is an integer 0 or 1;
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0 = least sensitive or only range
1 = more sensitive range, if fitted
Data returned: <full_scale> <units> 1 <dec_places> <gas> <active>*
or, if channel or range not present: NF
Where: <full_scale> full scale reading as a decimal number
<units> number representing the ASCII code for a character indicating gas
units:
112 = („p‟) ppm (parts per million)
118 = („v‟) vpm (volume per million)
103 = („g‟) mg/m3 (milligrammes per cubic metre)
37 = („%‟) percent concentration
<dec_places> number of decimals readings are shown
to on analyser screen.
<gas> number representing the measured gas:
1: CO - Carbon Monoxide
2: CO2 - Carbon Dioxide
3: O2 - Oxygen
4: SO2 - Sulphur Dioxide
5: SF6 - Sulphur Hexafluoride
6: NO - Nitric Oxide
7: N2O - Nitrous Oxide
8: NH3 - Ammonia
9: CH4 - Methane
10: C2H2 - Acetylene
11: C2H6 - Ethane
12: C3H8 - Propane
13: C4H10 - Butane
14: C5H12 - Pentane
15: C6H14 - Hexane
16: C6H6 - Benzene
17: C6H5CH3 - Toluene
18: HCL - Hydrogen Chloride
19: ratio - Ratio of gas 0 to gas 1
<active> (only returned by version 2.07 or later)
1 = this is the range currently selected for this gas
0 = this range is not selected
Example replies: <S>1GRRD 0 100.0000 37 1 1 2<E>
range reads 0.0 .. 100.0% CO2 <S>1GRRD 0 1000.0000 118 1 0 7<E>
range reads 0 .. 1000vpm N2O
9.6.4 Show Calibration Information
This command is supported by firmware version 2.07 and later.
This command returns the calibration factors used by the MGA analyser. By reading these
factors before and after a calibration, it is possible to see by how much the calibration has
„moved‟ the zero/span. Factors are held separately for each range and gas.
Command: GRCL
Parameters: <channel> <range>
Where: <channel> is an integer 1..4 selecting possible channel
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(which equates to a specific gas)
<range> is an integer 0 or 1;
0 = least sensitive or only range
1 = more sensitive range, if fitted
Data returned: <span_factor> <zero_offset>
Where: <span_factor> Is an integer representing the span
factor multiplied by 10000.
e.g. a value of 10000 represents a span factor of 1.0, the
nominal value.
<zero_offset> Is an integer representing the zero offset
9.6.5 Show sample gas inlet
Sample switching varies depending on options fitted. Most models are fitted with gas
switching for zero and a single span gas. Multi inlet options cover 2, 8 or 16 sample inlets.
Note that inlet numbering as shown on the analyser screen is 1 higher (i.e. numbering starts
at 1).
Command: GRMW
Parameters: none
Data returned: <I>
Where: <I> is a number representing the analyser gas as follows: -1 = zero calibration gas
-2 = span calibration gas
0 = first or only sample inlet
1 .. 15 = other sample inlets (as options fitted)
9.6.6 Show analyser gas flow and sample pump state
The flow reading comes from a mass flow meter which is in series with the analyser cells.
The flow reading is non-linear, for guidance only. Flow readings vary from 0 (no flow) to
1023 (maximum flow), and a reading of 800 approximates to a sample flow of 600 ml min-1,
the recommended nominal sample flow for most applications.
Command: AFLO
Parameters: none
Data returned: <flow> <pump>
Where: <flow> is the sample flow, 0 .. 1023 (see above) <pump> is sample pump state: 0=off, 1=on
Example reply: <S>1AFLO 0 800 1<E>
sample flow is approx. 600ml min-1, pump is on
9.6.7 Show Alarm and Valve States
This command is supported by firmware version 2.07 and later.
The MGA has eight „ports‟ which may be used for trip relays or gas switching valves. The
assignment of relays and valves to ports depends on the specification of the specific analyser.
Normally, ports 1 to 4 correspond to trips 1 to 4 (as fitted). Where trip 5 is fitted, this
corresponds to port 8.
When using this command to interrogate the state of trips, bear in mind that a trip can be
configured to make the relay operate either when the trip condition is met, or when it is not
met. The trip setting will therefore determine whether a port state of 1 means tripped, or
not tripped.
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Command: GRTP
Parameters: none
Data returned: <p1> <p2> <p3> <p4> <p5> <p6> <p7> <p8>
Where: <px> is the state of port „x‟
0 = relay not operated or valve closed
1 = relay operated, valve closed Example reply: <S>1GRTP 0 0 1 0 0 1 0 0<E>
ports 3 and 6 are in the active state.
9.6.8 Show analyser's gas name(s)
Example1 command: *GNME 1 Response 0GNME 2 CO2 (shows 1st gas name is CO2) Example2 command: *GNME 2 Response 0GNME 2 CH4 (shows 2nd gas name is CH4)
9.7 Remote Control Commands
The MGA analyser has two modes:
Remote control mode – front panel controls are ignored, all appropriate AK commands
accepted.
Manual control mode – front panel controls are available, only interrogation AK
commands are accepted.
The two modes avoid conflict between commands from front panel and remote control, as
only one can be in control at any time.
9.7.1 Set remote control mode
This command disables the front panel controls and enables all appropriate AK commands. It
can be sent to the analyser at any time. Command has no effect if the analyser is currently
in remote control mode.
Command: SREM
Parameters: none
Data returned: none
9.7.2 Set local control mode
This command enables the front panel controls. Setting AK commands are no longer
accepted. It can be sent to the analyser at any time. Command has no effect if the analyser
is currently in local mode.
Command: SMAN
Parameters: none
Data returned: none
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9.8 Measurement Enquiry Commands
These commands are not accepted during calibration.
9.8.1 Get current readings
Command: AKON
Parameters: none
Data returned: <r1> [<r2> [<r3> [<r4>]]]
Where: <rx> is current gas reading, as a fixed point decimal
number without units or gas name.
<r1> is always present, <r2> only if a second gas is fitted
<r3> if a third, etc.
The reading is for the currently selected range in each case.
Example reply: <S>1AKON 0 2.1234 45.1223<E>
This example is from a dual gas analyser. Use the GRRD command to get details of full scale, gas and units. Note that the first reading comes from the lowest numbered channel present, and that missing channels are simply skipped.
9.9 Range Selection
Only permitted when in remote control mode, and not calibrating.
9.9.1 Select active range
Error NF is returned if the selected range is not fitted.
Command: SEMB
Parameters: <channel> <range>
Where: <channel> is an integer 1..4 selecting gas / channel
<range> is an integer, 0 or 1;
0 = least sensitive or only range
1 = more sensitive range, if fitted
Data returned: none
9.10 Gas Inlet Control Commands
These commands are only accepted in remote control mode, and will be rejected during
calibration.
9.10.1 Select sample inlet
Multi inlet options cover 2, 8 or 16 sample inlets. Valid parameters for inlet are 0 through
[number of inlets – 1]. Inlet 0 is always present. Command: SMGA
Parameters: <inlet>
Where: <inlet> sample inlet number as an integer.
If multiple inlets are not fitted, this must be zero
Error NF is returned if the selected inlet is not fitted.
Data returned: none
Note: inlet numbers displayed on the analyser screen start at 1, not zero. e.g. if SMGA
command is used with inlet parameter „2‟, the analyser screen will show the inlet as „3‟.
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9.10.2 Select zero gas
This command switches zero gas through the analyser, to allow for zero check. Calibration is not attempted - concentrations can be read as normal. Error NF is returned if a zero gas
switching valve is not fitted.
Command: SNGA
Parameters: none
Data returned: none
9.10.3 Select span gas
This command selects span gas through the analyser, to allow for span check. Calibration is not attempted – concentrations can be read as normal. Error NF is returned if a span
switching valve is not fitted.
Command: SEGA
Parameters: none
Data returned: none
9.10.4 Sample pump control
Controls the analyser‟s internal sample pump. Note that error NF is returned if an internal
sample pump is not fitted.
Command: SRPS
Parameters: <on_off>
Where: <on_off> an integer to control the pump
0 to turn off the pump, <>0 to turn it on
Data returned: none
9.11 Calibration Commands
Again, these commands are only accepted in remote control mode, not when calibration is in
progress. Zero and span commands are only accepted after warm-up for all channels in
complete.
9.11.1 Perform auto-zero
Firmware version 2.07 and later offer two zero modes; „instant‟ and „automatic‟, specified by
an optional parameter. Earlier firmware allows only „automatic‟ zero.
For either case, zero is performed for all gasses and ranges simultaneously.
An automatic zero calibration executes as follows:
Freeze analogue output(s)
If a zero gas switching valve is fitted, switch to zero gas
Wait for a preset purge time interval
Attempt to set zero for all fitted gasses and ranges
Switch to sample gas (using previously set inlet)
Wait for preset purge interval
Release analogue output(s)
Automatic zero may take a few minutes to complete, depending on the gasses and ranges
fitted. Automatic zero cannot be aborted once started.
An instant zero calibration attempts to set zero using the current contents of the measuring
cells. There are no gas circuit changes or delays. It is assumed that the analyser is fully
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purged with zero gas before sending an Instant zero command. Instant zero completes in 1-
2 seconds.
No error is given if the zero adjustment fails for any gas. Perform a zero check to verify if necessary. The SATZ command is not acknowledged until the zero cycle is completed.
Error WMUP is returned if this command is attempted while any channel is warming up.
Command: SATZ
Parameters: [<instant>]*
Where: <instant> is a letter „I‟, and, when present causes an instant
zero calibration.
This parameter is ignored prior to firmware 2.07.
Data returned: none
9.11.2 Set span gas concentration
This command is used to set the expected span gas concentration for a given gas channel and range and is used prior to performing a span adjustment. Error NF is returned if the
given channel or range is not fitted.
Command: SPGA
Parameters: <channel> <range> <conc>
Where: <channel> is an integer 1..4 selecting gas / channel
<range> is an integer 0 or 1;
0 = least sensitive or only range
1 = more sensitive range, if fitted
<conc> is a real value specifying span gas concentration
as a proportion of the full scale range.
Accepted values are from 0.5 to 1.0. Values can be set to three decimal
places.
Data returned: none
Example command:
Range 1 on channel 2 is 5% CO2 full scale. We wish to set the analyser to expect 4.17%
span gas:
<S>*SPGA 2 1 0.8340<E>
9.11.3 Perform span calibration
This command causes the MGA analyser to calibrate the given gas and range immediately,
using the current gas measurement.
Before sending this command, ensure that:
Correct span gas has been applied to the analyser
Analyser cells have been purged with span gas
Reading has stabilised
Failure to verify any of these prerequisites may result in inaccurate span!
Only the selected range and channel is calibrated. The status of the calibration is reported. Error NF is returned if the given channel or range is not fitted. Error WMUP is returned if this
command is attempted while any channel is warming up.
Command: SATS
Parameters: <channel> <range>
Where: <channel> is an integer 1..4 selecting gas / channel
<range> is an integer 0 or 1;
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0 = least sensitive or only range
1 = more sensitive range, if fitted
Data returned: none *
* Note: error ERR is returned if the calibration failed.
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10. IMPLEMENTATION NOTES
The following provides guidance when writing software to communicate with the MGA
analyser.
1) The MGA analyser can handle only one AK packet at a time. Do not send a second
command until the reply is received from the first.
2) There may be a delay in processing commands at certain times (e.g. during calibration).
If the analyser is set to perform automatic zero periodically, it may be minutes before
responding.
3) There may be some delay between receiving the first part of the reply packet and the
end code. This delay may be some seconds for certain (notably calibration) commands.
4) The gas concentration readings are calculated every 800mS approximately. There is no
advantage in polling for readings at a rate faster than this.
5) The number and position of spaces in AK packets is important; each parameter must be
preceded by a one or more spaces. Any spaces following the last expected parameter
are ignored. There are no spaces between the <S>, address and command.
6) Where a real (or fractional) parameter value is expected, number strings with zero up to
four decimal places are accepted, as are leading zeroes. The decimal point is optional.
Scientific format (exponent) number strings are not accepted.
7) Where an integer numeric parameter is expected an arbitrary number of leading zeroes
are accepted. Decimal points are not allowed in integer parameter values. See
command descriptions for parameter details.
8) The MGA returns real number values formatted as fixed point with four decimal places.
9) Performing a „soft reset‟ allows remote control mode to be cancelled without using the
serial link. Pressing the top and bottom soft keys together performs a soft reset – the
analyser will perform a warm start and return to local control.
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11. KNOWN ISSUES
This list is comprehensive as of the date of printing.
When switching to remote control using the SREM command, ensure that the main results
screen is displayed. Other screens may appear corrupted by remote control commands.
Sample gas may be restored on setting the analyser back to local control if span or zero gas
was previously selected.
Analyser fail indication (bit 0 in status code digit) is not yet implemented – all other
indications work as described.
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Authorised Local Agent:
ADC Gas Analysis Limited
Unit 35, Hoddesdon Ind. Estate
Pindar Rd, Hoddesdon
Herts, EN11 0DB
United Kingdom
Tel: +44-1992478600 Fax: +44-1992478938
Email: [email protected]
Web: http://www.adc-gas.com