Representatives & Distributors World Wide

Expo Technologies Ltd

Sunbury-on-Thames,

England

Expo Technologies, Inc

Twinsburg OH,

USA

Expo Technologies

Your Support Network

Main Factory Location

Heathrow City

Gatwick

Sunbury

Applications suitable for Exp

• Control Panels

• Switchgear

• Motors

• Generators

• Analysers

• Rooms/Buildings

Principle of Operation

Flow Sensor

PurgeInlet

PurgeOutlet

Pressure Sensor

Minimum Pressures

Standard Minimum Pressure

IEC60079-2: 2007 (Zone 1) 50 Pa / 0.5 mbar (0.2” WC)

IEC60079-2: 2007 (Zone 2) 25 Pa / 0.25 mbar (0.1 WC)

Australia AS2380 Pt 4 50 Pa / 0.5 mbar (0.2” WC)

Europe EN 50016 50 Pa / 0.5 mbar (0.2” WC)

USA NFPA 496 25 Pa/o.25 mbar (0.1” WC)

Measured at the “eye” of the fan

Pressurized Enclosure

PE

Inlet for

Protective

Gas

Purge

Outlet

Purge Flow

Sensor

Low Pressure

Sensor

FE

Terminology

• Static Pressurization

– Enclosure is purged & pressurized but sealed

• Leakage Compensation (LC)

– Enclosure is purge & pressurized

– Switches to small flow (tops up any leakages)

• Continuous Flow (CF)

– Enclosure is purged & pressurized

– Purge flow continues (dilutes internal release)

Basic Build Requirements

• Flow meter

– monitors purge (and subsequent) flow rate

– no over-ride

• Pressure sensor 1

– monitors minimum required overpressure

Pressure sensor 2

– protection against excessive overpressure

• Alarm / Isolation of electrical equipment

– if overpressure falls below 0.5mb (Zone 1)

System types

Equipment being

protected

Zone 1Division 1

Zone 2Division 2

Non-Ex

Equipment

Auto-DisconnectAuto-Timer

Ex px

X-Purge

Alarm OnlyManual

Ex pz

Z-Purge

Ex-Equipment

(Ex n / mb)

Alarm OnlyManualEx py

Y-Purge

Custom Enclosures

Motor Purge systems

Purge Time

• IEC Standard

– Equal to 5x enclosure volume

• NFPA Standard

– Equal to 4x enclosure volume

– 10x enclosure + rotor volume (for motors)

• Practical limit (user-defined?)

– 60 minutes for large motors & compressors

– 30 minutes for cabinets

– 10 minutes for portable equipment

Pneumatic Timer

Based on R – C network

– R = pneumatic restrictor

– C = pneumatic reservoir

R

C1 C2 C3

Electronic Timer

• Accurate & Repeatable

– 1 to 99min (-0/+3 secs)

• Intrinsically Safe

– Ex ia IIC T6

• Field-replaceable battery

– 3 year service life

– 10 year storage life

• Global Approvals

– ATEX / IECEx / FM / UL (pending)

• LED Purge Progress Indicator

Motor Purge Systems

Motor Systems G.A.

Typical Settings

Pressure Point Pressure Leakage Nl/min

Minimum Acceptable Pressure 150Pa, 1.5mbarg

Normal Working Pressure 1kPa, 10mbarg Client continuous air usage

Relief Valve Lift-off Pressure 3.0kPa, 30mbarg Clients air usage during the

purge period

Test Pressure (RLV x 1.5) 4.5kPa, 45mbarg Must hold the pressure for 2

minutes without distortion

Witnessed Purge Test required for every motor to ensure

compliance with the first motor tested / certified

Typical Motor Purge System

Relief Valve

Exe Junction Box

D758

Typical Internal

CLAPS:

Closed Loop

Automatic

Pressurization

System

Typical Alarms

• Loss of Pressurization (Alarm/Shutdown)

• Intermediate Pressure (Alarm)

• Permissive Contact (Shutdown)

• Electronic Options: Ex e or Ex i circuits

• Pneumatic Options: Pushrod into Ex d box

Expo Motor Systems Coding

5 X LC / ss / ET / OV / PA / PC / D758

System SizeEach number represents a

certain amount of air flow

(NI/min)

3: 500-1500

5: 2000-6000

7: 7000- 14000

Purge MethodLC: (Leakage

Compensation)

CF: (Continuous Flow)

ET: electronic timer. If

it uses a pneumatic

timer then this block is

not included

Standard OutputsPA: Power Alarm

PO: Pneumatic Output

IS: Intrinsically Safe

Model variant

Many types available, some

OEM specific, some general

Hazardous Area ApplicationX: covers dust and gas protection and

has a timer

Y: only covers dust protection

Z: covers dust and gas protection but is

manually timed

Housing

ss: stainless steel box

pm: panel mount

bp: back plate

nm: non metallic

co: chassis only

Standard Options

OV: Outlet Valve

AO: Alarm Only

MO: Manual Override

Non standard output optionsAA: Active alarm output fitted

AC: Alarm cancellation circuit

AS: Alarm ‘Action on pressure of flow failure’ selector valve

DS: Door Switch Power interlock fitted

DT: Delayed Trip after pressure or flow failure

FM: Flow Meter(s) fitted

MT: Mechanical Timer

OA: On/Off switch controlling protective gas or logic supply

OB: On/Off switch controlling logic supply only

OC: On/Off switch controlling protective gas only

PC: PE pressure control leakage compensation valve

SS: Separate supply for protective gas and logic air

TW: Twin (or more) outputs for PEs purged in parallel.

Advantages of Ex p for motors

• Only practical solution for high power units

• Clean air purge removes environmental contaminants

• Easier to achieve IIC compliance

• High level of security & confidence

– Monitored systems

– External alarms

– Power interlock

Typical Installation – Drillers Console

1ZLC/bp/IS

1ZLC/pm/IS

Custom Enclosures - internal

Custom enclosure - external

Typical enclosure systems

Mini-X-Purge

Mini-Y-PurgeInterface Box

Purge system selection

• Hazardous Area standards

– ATEX / IECEx / NEC / CSA / INMETRO

• Zone or Division

– X-purge or Z-purge

• Enclosure contents

– Ex ratings, power, T rating

• Enclosure Size / Purge Time

– Determines required air flow capacity

Minimum requirements

Overpressure test

1.5x manufacturers rating (typically 30–50mbar)

Doors to be opened with tool (Zone 1)

IP4X (Zone 1)

7Nm (4Nm on windows)

UV resistance test

Standard cabinets pass the above but leak!

Custom Cabinets

Empty cabinet,

Manufactured with Exp system

Populated cabinet,

Expo-inspected, ATEX or IECEx certified assembly

Custom Enclosures

Zone 1 (ATEX Cat 2)

– Pressurized Enclosures

• Expo PE2

– Increased Safety

• Expo PE2E

Zone 2 (ATEX Cat 3)

– Pressurized Enclosures

• Expo PE3

– Increased Safety

• Expo PE3E

Custom Enclosures - Zone 1 (ATEX Cat 2)

• Pressurized Enclosures PE2

– Expo construct OR verify clients assembly

Schedule of Limitations

GA drawings & Component List

– 3rd Party Certificate in Expo name:

IECEx: ITS 08.0044X

ATEX: ITS10ATEX16944X

-20 to +55°C

Ex px IIC T4 Gb

Ex p IIIC T135°C

Expo-Intertek Schedule of Limitations 1

Maximum

Size *

2100 mm (82.68”) H x 1800 mm (70.87”) W x 1000 mm

(39.37”) D

Maximum volume = 3780 Litres

Purge TimePurge Time must reflect 10 volume changes and be

between 10 and 30 minutes

Layout *30% minimum free space, in any cross section of any

plane of the enclosure.

* Can be exceeded: requires witnessed purge test

Expo-Intertek Schedule of Limitations 2

Ventilation of

Internal Items *

Internal closed items require minimum ventilation holes of

1cm²/litre to avoid potential trapped gas. If necessary,

increase existing holes to suit or make new/additional holes

(min. size 28.2mm2 or 0.043in2)

Closed items need ventilation distributed equally at the top

and bottom surfaces.

Permitted Closed

Items

Hermetically sealed or potted devices.

Allowed if total volume of such sealed items < 1% of the

internal free volume of the enclosure, and:

- the item does not contain any potential source of ignition, or

- the item is Ex d, Ex e (no batteries), Ex i, Ex m or Ex n

certified

* Can be exceeded: requires witnessed purge test

Expo-Intertek Schedule of Limitations 3

Heat

Dissipation

Two temperature limiting devices must be used (one can be

used to initiate a cooling system).

Batteries or

Cells

The following approved batteries are allowed:

CR2032 (VARTA or Panasonic)

CR½ AA (VARTA or Sonnenschein)

SL-340 (Tadiran or Sonnenschein)

** Non-approved batteries require an Expo “Battery Test”

Fans

Maximum airflow permitted: 400 litres/sec (14.125 ft3/sec)

Inlet Position > 200 mm (7.78”) from air leakage points, e.g.

door gaskets or access plate gaskets.

* Can be exceeded: requires witnessed purge test

Expo-Intertek Schedule of Limitations 4

* Can be exceeded: requires witnessed purge test

Optical Devices Low power communication devices are allowed.

Permitted

Thru-Wall

Components

Devices or components mounted through the enclosure

wall must have a suitable IP rating for the enclosure and

must either be metallic (or if non-metallic, must be Ex

rated - demonstrates compliance with UV & Impact

specification).

Cable Glands, Conduits and Sealing Systems shall be

Ex-certified and suitable for use with the cable type and

in the required Hazardous Location.

Expo-Intertek Schedule of Limitations 5

Isolation of

Electrical Inputs

to the Enclosure

ALL electrical supplies (power & signals) that enter the

enclosure NOT individually protected by another explosion

protection technique MUST be automatically isolated

following the ALARM signal of the Expo Purge Control

system.

Hot Internal

Components

Internal devices with surface temperature above T4 (135 ºC)

must be declared, and extra precautions identified and

specified.

Examples are: filament lamps, power semiconductors,

thyristors, heaters, power resistors, etc.

Achievable certification

Hazardous Area

Classification

Ex px IIC T4

Maximum range for Tamb = -20ºC to +55ºC

NOTE: fitted certified apparatus with more restrictive

classifications (T rating and/or Gas Group) will reduce the

overall classification of the PE, and the supplied labelling

will be modified to suit.

What we need

Bill of Materials (BoM)

General Assembly Drawings (GA)

Circuit Schematics

Power & Signal Isolation design

Data Sheets & Certificates

for hazardous area rated equipment and devices

What you get

• Expo guidance on equipment selection

• Expo test/verification of content

• Expo Declaration of Conformity

– IECEx

– ATEX

– Enclosure labels

– Instruction Manual

Extra considerations

• Internal source of release

– Notified Body test

– Nitrogen purge

• Most Ex HMI’s will fail over-pressure test

– Fit into separate inset housing, non-Exp

• Ex equipment must match overall approval

– ATEX devices must be ATEX marked

– IECEx devices must be IECEx marked

Purge Flow Monitoring

Orifice Plate

(changeable)

Z-Purge CF: Control Unit, Relief Valve

• SS Boxed, top or side mounting

• PM Panel mounting (inset)

• BP Back-plane

CF systems include spark arrestor

Z-Purge LC: Control Unit, Relief Valve

• SS Boxed, top or side mounting

• PM Panel mounting (inset)

• BP Back-plane

Purge in Progress indicator

Spark Arrestor flow capacity

Enclosure Volume

O/P

No.

ft3 (4x volume) m3 (5x volume)

1 3.0 0.06

2 8.3 0.15

3 10.5 0.24

4 17.2 0.39

5 24 0.54

6 36 0.81

7 48 1.08

8 60 1.35

Z-Purge

• Zone 2 / Div 2 use

• Versions:

– CF Continuous Flow

– LC Leakage Compensation

• Manual operation

– Manual timing

– Alarm on loss of pressurization

• Local indicator

• Volt-free contact (for wiring by others)

X-Purge Systems

X-Purge, direct top mounting

Multiple Enclosures

HMI without Ex approval

• Window to meet impact test

• Push-rods operate buttons

• No product modification

SmartPurge

• 316 SST

– Enclosure

– Pushbuttons

– Spark Arrestor

• IECEx / ATEX

• Ex [px] IIC T4/T6

– -20 to +60 DegC

SmartPurge System

• Controls up to 540 l/min

• Switches up to 6A

• Purge up to 99min

• Delay up to 99min

SmartPurge accessories

• I.S. solenoid valve for air inlet

• Remote panel (50m max)

• Manual override key switch

SP2- DV

SP2- SIU

SP2- CF

SP2- RP

Ex p systems

• Simple in principle

• Solves unique and difficult problems

• Allows manufacturers to extend their market application with limited outlay

• Integrates other protection concepts easily

EXPO: Solution Provider