testing & commissioning procedure hvac

8/10/2019 Testing & Commissioning procedure HVAC

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BUILDING SERVICES BRANCH

TESTING AND COMMISSIONING

PROCEDURE NO. 1

FOR

AIR-CONDITIONING, REFRIGERATION,

VENTILATION AND CONTROL SYSTEMS

IN

GOVERNMENT BUILDINGS

HONG KONG

? HONG KONG SPECIAL ADMINISTRATIVE REGION GOVERNMENT

Building Services BranchArchitectural Services Department(2000 Edition)


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COPYRIGHT

1. This Testing and Commissioning Procedure is solely compiled for use on Air-

conditioning, Refrigeration, Ventilation and Control Systems in Government Buildings ofthe Hong Kong Special Administrative Region.

2. This Testing and Commissioning Procedure is copyrighted and all rights (includingsubsequent amendment) are reserved.

3. It is hereby declared that the procedure contained therein may not be pertinent orfully cover the Air-conditioning, Refrigeration, Ventilation and Control Systems carriedout by other Government Departments or private sectors. Prior consent by the Director ofArchitectural Services must be obtained for adoption of this testing and commissioning procedure for Air-conditioning, Refrigeration, Ventilation and Control Systems of othernature or locations.


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TABLE OF CONTENT Page

1. Introduction 1

2. General Requirements 1

3. Testing and Inspection 2

4. Statutory Inspection/Commissioning 3

5. Calibrated Equipment 93

Appendix A Page

Testing and Commissioning Certificate on Air-conditioning, Refrigeration,Ventilation and Control Systems

Part 1 : Details of Project 1

Part 2 : Declaration 1

Part 3 : Items Inspected and Tested 2

3.1 The General Requirements as indicated in the T & C procedurehave been complied with.

2

3.2 Precommissioning Checks 2

3.3 Setting to Work & Balancing 2

3.4 Comments 6

Part 4 : Test Record attached to the Test Certificate 7

4.1 General 7

4.2 Packaged Water Chillers 7

4.3 Air-Cooled Condensing Sets 8

4.4 Cooling Towers 9

4.5 Pumps (Medium) 10

4.6 Air Handling Units 11

4.7 Heating Coils (Not included in Air Handling Unit) 13


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TABLE OF CONTENT Page

4.8 Ducts, Grilles, Diffusers etc. 13

4.9 Testing Equipment 14

Appendix B Page

Testing and Commissioning progress chart for Air-conditioning, Refrigeration,Ventilation and Control Systems

1

Appendix C Page

Flow Chart for Testing and Commissioning Procedure on Air-conditioning, Refrigeration, Ventilation and Control Systems

1

Figure 1 Example of Water Distribution System 2

Figure 2 Example of Air Distribution System 3

Figure 3 Example of Air Distribution Branch 3

Figure 4 Example of Low Velocity Supply Air System 4

Figure 5 Example of Air Flow Sheet 5


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B.S.B. Testing and Commissioning Procedure No. 1Air-conditioning, Refrigeration, Ventilation and Control Systems

1. Introduction

1.1 This procedure is intended to lay down the minimum testing andcommissioning requirements to be carried out by the Contractor on a newAir-conditioning, Refrigeration, Ventilation and Control Systems uponcompletion or on an existing Air-conditioning, Refrigeration, Ventilationand Control Systems after a major alteration. Additional testing andcommissioning (T & C) requirements may be proposed by the Contractoras appropriate and agreed by the Project Building Services Engineer(PBSE), e.g. for special equipment supplied and/or installed by theContractor.

1.2 This procedure is also written to facilitate the PBSE and Project BuildingServices Inspector (PBSI) in carrying out the following aspects of workwith respect to T & C.

(i) To vet and approve the T & C procedures proposed and submitted bythe Contractor.

(ii) To witness those T & C procedures as specified.

(iii) To receive the T & C certificate and other supporting data.

2. General Requirements

2.1 The Contractor shall submit the T&C procedures to the PBSE for approval.The submission shall be made at least one month before thecommencement of T&C.

2.2 Where tests are required to be witnessed by the PBSE/PBSI, the Contractorshall give due advance notice (usually not less than three days) and providedetails of date, time and type of tests to be performed.

2.3 Upon completion of such T & C procedure, the Contractor shall completeand sign a testing and commissioning certificate as Appendix A, to theeffect that agreed T & C procedures have been duly carried out.

2.4 Before carrying out any test, the Contractor shall ensure that theinstallations comply with the statutory requirements and regulations.

2.5 Part of the testing & commissioning may be required to be carried out in

Suppliers premises in accordance with the provisions in theGeneral/Particular Specification.

2.6 The testing & commissioning of systems under various sections may be


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required to be carried out in parts or as a whole depending upon the statusof the progress of work or as dictated by the requirements of the Contract.

2.7 It must be ensured that the personnel carrying out the tests are trained,experienced commissioning engineers and for specialised items such asrefrigeration plants, control equipment etc., these may be carried out by themanufacturers own T & C engineers if necessary.

3. Testing and Inspection

3.1 The requirements are in general as specified in the latest GeneralSpecification for Air-conditioning, Refrigeration, Ventilation and ControlSystems issued by Building Services Branch of Architectural ServicesDepartment, herein after described as General Specification. If there is anydiscrepancy between this procedure and the General Specification, theGeneral Specification shall take precedence.

3.2 The Contractor shall carry out the tests and inspections as shown in Part 3and record the test results on Part 4 of Appendix A and as agreed betweenthe Project BSE and the Contractor.

3.3 The Contractor shall provide all the necessary staff, labour, materials andequipment for a thorough test and examination of the installation.

3.4 The purpose of this T & C procedure is to provide the Contractor aguideline which would ensure that the building environmental systems produce the design objectives. It includes :

(i) The balance of air and water distribution.

(ii) The adjustment of total system to provide design quantities.

(iii) The electrical measurement.

(iv) The verification of performance of all equipment and automaticcontrols.

(v) The sound and vibration measurement.

3.5 The objectives as outlined above can be accomplished by :

(i) Checking installations for conformity to design.

(ii) Measurement and establishment of fluid quantities of the system asrequired to meet design specification.

(iii) Recording and reporting the results.

3.6 The procedure covers the following sections of testing & commissioning :

(i) Preliminary checks


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(ii) Setting to work and balancing the systems

(iii) Recording of test data

4. Statutory Inspection/Commissioning

4.1 After the proper testing and commissioning of the Air-conditioning,Refrigeration, Ventilation and Control Systems, the Contractor shall notifythe appropriate Authority, through the PBSE, on the completion of theinstallation and its readiness for inspection and testing.

4.2 Before operating the system to carry out T & C, the following steps should be followed :

(i) Obtain design drawings and specifications and to be thoroughlyacquainted with the design intent.

(ii) Obtain copies of approved shop drawings of all air handlingequipment, outlets (supply, return and exhaust) and temperaturecontrol diagrams.

(iii) Compare design to installed equipment and field installation.

(iv) Check the system from the air handling equipment to terminal unitsto determine variations of installation from design.

(v) Check filters and dampers (for both volume control and fire protection) for correct and locked position, and temperature controlfor completeness of installation before starting fans.

(vi) Obtain manufacturers outlet factors and recommended procedure oftesting. Summation of required outlet volumes permits a crosscheckwith required fan volumes.

(vii) Obtain schematic diagrams of system as-built ductwork and pipinglayouts to facilitate reporting.

4.3 During construction certain tests will have been carried out on the

installations to ensure their suitability for operating at the designconditions. Such test certificates have to be issued together withcertificates of any works tests.

4.3.1 Works Tests

a) Works tests shall be carried out in accordance with the typenormally associated with the specified item of equipment andto the standards as laid down in the Specification and theConditions of Contract.

b) Works static pressure tests will be carried out on such items of plant and equipment as pressure vessels, water coils, heatexchangers and plate exchangers, radiators and convector


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elements, and all items of plant or equipment handlingrefrigerant, as laid down in the Specification and theConditions of Contract.

c) Dynamic rotation tests will be carried out on such items as fanimpellers and drives, compressor, pump impellers and drives.Tests shall be conducted through the entire rotational speedrange up to a maximum of 150% design operating speed if the provision have been made in the Conditions of Contract. Whenitems of plant are purchased ex-stock, manufacturers testcertificate will suffice.

d) Rotational test on electric motors will not be carried out if theequipment is constructed to the requisite current BritishStandard or any other approved standards.

4.3.2 Welds in Piped Services

a) The welds shall be inspected by means of cutting. The totalnumber of welds to be inspected should be limited to 2.5% ofthe total. If any of the welds are found to be of sub-standard,equal number of further welds shall be cut out.

b) At least two welds per operative shall be inspected. Eachwelder employed on the works shall be allocated anidentification number and each site weld shall be stamped withthe appropriate identification number to identify the operative.

c) Where required by the Particular Specification, some welds onlarge bore or high pressure mains may be subject to testing byradiographic or ultrasonic methods. Such non-destructivetesting should be carried out by specialized laboratories who both perform the tests and analyse the results.

4.3.3 Pressure Testing of Piped Services

a) Pressure testing of piped services systems, or any section of acompleted system, shall be completed prior to the application

of any thermal insulation to the cleaned pipe surfaces. b) Ensure that all plugs, caps, tees and drain fittings required to

enable the tests to be carried out have been provided.

c) Before hydraulic tests are carried out, all safety valves, gaugesetc. shall be effectively isolated or removed. For all non-destructive safety equipment, these shall be effectively tested attheir design working pressure during commissioning of theinstallation.

d) Tests on lengths of pipe or portions of systems shall be applied by filling the section to be tested with water and raising its pressure to the figure quoted in the Specification.


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e) The section shall then be left fully isolated without furtherstrokes of the pump and all joints must remain watertight for a period of at least two hours. As to whether or not the section issound shall be governed by the rate at which the pressure falls.

f) Any fault discovered during such tests shall be at onceremedied and the test reapplied until the section under test isconsidered sound. Remedial work shall conform with all therequirements of the General and Particular Specification formaterials and standards of workmanship.

g) Upon completion of the test, the water shall be released anddrained away as rapidly as possible, the section being thenthoroughly sluiced through to ensure the removal of as muchdirt and dross as possible before being refilled and put intoservice.

4.3.4 Air Leakage Test for Ductwork

a) Where required by the Specification, all air-conditioning supplyductwork connected to central air handling units shall be testedfor air leakage in accordance with - HVCA (V12) Specificationfor Sheet Metal Ductwork (DW series).

b) For preliminary and visual test, the method will include usingchemical white smoke generators. All openings in theductwork shall be properly sealed followed by the introductionof smoke.

4.4 The flow-chart in Appendix C provides the sequence, responsibilities andguidelines for the testing and commissioning procedure.

4.5 Precommissioning Checks

4.5.1 Water Distribution System

4.5.1.1 System Cleanliness

Irrespective of the precautions taken during the constructionstage to keep the internal surfaces of pipework clean, it should be assumed that it has not been done so and one of thefollowing procedures shall be used to clean the system.

4.5.1.1.1 Flushing

a) Divide the pipework system into self-draining sections so thatthe maximum possible flushing rate is achieved.

b) Isolate items which are particularly sensitive to dirt, such as pumps, small bore coils and tubes, including induction andother room unit coils and spray nozzles. Washers, cooling


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tower basins, feed and other tanks which may haveaccumulated with deposits during manufacturing or installationshould also be isolated and flushed independently.

c) Where make-up or feed tanks are used for flushing, ensure thatthe maximum possible pressure is sustained on the systemduring the flushing process. This may necessitate the provisionof a temporary parallel feed of mains water into the tank wherethe ball valve has limited capacity. This procedure assumesthat the connection of the section from the tank is at a high point in the section being flushed.

d) Ensure :

(i) that flushing is carried out from the upper to the lowersections of a multi-section system, finishing with thelowest point; initial flushing should always be from small

bore to large bore pipe. Particular care is required onreverse return systems and systems with roof-top chilleror boiler plant;

(ii) that the large bore outlet is not opened until the section being flushed is fully primed;

(iii) that the maximum possible flow rates are used;

(iv) that flushing continues until the outflow runs clear.

4.5.1.1.2. Cleaning by Forced Circulation

Where facilities exist, final cleaning of systems can beachieved by circulation of the medium in order to collect dirt atfilters or other selected points in the system. Where circulationis achieved by the use of a pump, this action shall be deferreduntil the pump has been set to work in accordance with para.4.6.1.4.

4.5.1.1.3 Chemical Cleaning & Corrosion Inhibiting

Chemical cleaning, if required, shall be carried out as specified by the specialist. Corrosion inhibiting, where specified, should be carried out after flushing.

4.5.1.2 State of System

Check :

(i) that where special valve packing is required, e.g. greasein medium or high temperature system, this shall be inaccordance with manufacturers instructions;

(ii) that pressure tests have been completed throughout;


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(iii) that the system has been cleaned in accordance with para.4.5.1.1;

(iv) that permanent water connections have been made;

(v) that water treatment is available if specified.

4.5.1.3 Check of System before Filling

Check :

(i) that probes, pockets, pressure gauges, siphons, orifice plates and taps, and air vents are installed;

(ii) that drains and overflows are connected and free from blockage;

(iii) that connections to heating and cooling coils and all otherheat exchangers are correct in relation to the design waterflow direction;

(iv) that control and non-return valves are installed the rightway round;

(v) that relief valves are installed as specified and are free tooperate;

(vi) that relief valve outlets are piped away to suitable drain points;

(vii) the expansion devices for alignment and freedom fromobstruction;

(viii) the presence of special pump priming devices wherespecified;

(ix) that the strainer mesh is of the correct grade and material;

(x) that the changeover devices for duplex strainers areoperative and that there are means of isolation for singlestrainers;

(xi) that washers, tanks, nozzles and filters are clean;

(xii) that tank covers are provided where specified;

(xiii) that drain cocks are closed and other valves are left openor closed according to the plan for filling (see para.4.5.1.5 below);

(xiv) that the feed connection is in its correct location;


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(xv) that all pipework and fittings are adequately supported,guided and/or anchored where applicable.

4.5.1.4 Mechanical Checks

4.5.1.4.1. Pumps

Check :

(i) the external cleanliness of the pumps;

(ii) that the flow direction is correct;

(iii) that all components, bolts, fixings, etc., are secured;

(iv) that the impeller is free to rotate;

(v) the level and plumb of pump and motor shaft and sliderails; direct drive pumps require particular attention inthis respect;

(vi) the anti-vibration mountings for correct deflection;

(vii) that the correct drive is fitted;

(viii) that the pipework imposes no strain at the pumpconnections;

(ix) the securing and alignment of pulleys and couplings;

(x) the belt tension and match;

(xi) the cleanliness of the bearing;

(xii) that the lubricant is fresh and of the correct grade;

(xiii) that the coolant is available at the bearings when

specified;(xiv) that glands are correctly packed and the gland nuts are

finger-tight only, pending adjustment to correct drip rateafter start-up;

(xv) that drive guards are fitted and the access for speedmeasurement is provided.

4.5.1.4.2. Motorized Valves and Float Switches

Check :

(i) that the valves are installed the correct way round;


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(ii) that the valve spindles are free to move;

(iii) for freedom from excessive looseness;

(iv) the fit of pins;

(v) the rigidity of the mountings;

(vi) the stiffness of the linkage members;

(vii) the tightness of locking devices;

(viii) the bearing lubrication.

4.5.1.5 System Filling

Charge the system with water (treated, if so specified) to a prepared plan, the object of the plan being successful venting by filling from the bottom upwards forcing the air to high points - for venting to atmosphere. Careful considerationshould be given to the stage of valves and air vents before andduring filling to avoid air-locks and excessive spillage. Takecare not to exceed the working pressure of the system whenfilling from a high pressure source. When the whole system isfilled, disconnect the filling source, open the permanent supplyand adjust the tank levels.

4.5.1.6. Electrical Checks

Prior to the initial running of any electrically driven pump,valve or electric water heater, the following procedures should be adopted.

4.5.1.6.1. With all Electrical Supplies Isolated

Check :

(i) the local isolation of motor and control circuits;(ii) that there are no unshrouded live components within the

panels;

(iii) that the panels and switchgears are clean;

(iv) that the motor and surrounding areas are clean and dry;

(v) that the transit packing has been removed from contactorsand other equipment;

(vi) that there is no mechanical damage to switchgears andthat thermostats are of a suitable range to operate at


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ambient temperature (see para. 4.6.1.2);

(vii) that all mechanical checks on the pump and motor orvalve are completed (see para. 4.5.1.4);

(viii) that all connections are tight on busbars and wirings;

(ix) that the internal links on the starter are correct;

(x) that all power and control wirings have been completedin detail to the circuit diagram (paying special attention tocircuits for star-delta connected or specially woundmotors);

(xi) that the fuse ratings are correct;

(xii) that the starter overloads are set correctly in relation to

the motor name-plate full load current;(xiii) that the dashpots are charged with the correct fluid and

the time adjustments and levels are identical;

(xiv) that insulation tests on the motor have been performedsatisfactorily;

(xv) that the adjustable thermal cut-outs are set correctly(check manufacturers test certificates);

(xvi) that all cover plates are fitted.

4.5.1.6.2 With the Electrical Supply Available

(i) Check that the declared voltage is available on all supply phases.

(ii) Where motor powers are substantial or reduced voltagestarting or complex interlocks are involved, the controlcircuit logic and the starter operation should be tested

before the motor is rotated. The supply should first beisolated by the withdrawal of the two power fuses notassociated with the control circuit or the disconnection ofcables. The red phase shall be used for control circuitnormally. The control circuit fuse must be checked toensure that it is rated to give the correct discriminatory protection to the control circuit cables. The controlcircuit should be activated and the starter operationobserved. Adjust the timers. Check for positiveoperation of all contactors, relays and interlocks. Finally,open the isolators, reinstate the power connections andclose the isolators.

(iii) Where small motors have direct-on-line starting and


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simple control circuits, the starter operation, etc., should be checked when first starting the motor.

(iv) Never energize electric valve motors until the checks(para. 4.5.1.4.2), have been completed.

4.5.2 Air Distribution System

4.5.2.1 System Cleanliness

Prior to the fitting of filters and washer elements, ensure thatthe environment is clean and then proceed to check thefollowing for cleanliness :

(i) air intake screens;

(ii) fan and other equipment chambers;

(iii) floor gulley and all drainage traps;

(iv) fan internals;

(v) heater and cooler batteries;

(vi) cooling coil trays;

(vii) washer tanks;

(viii) humidifiers;

(ix) eliminators;

(x) dampers;

(xi) ducting and other airways;

(xii) sensing elements;

(xiii) terminal units;4.5.2.2 Air Regulating Devices and Other Components Within

Airways

Checks :

(i) that turning vanes, thermal insulation, acoustic linings, battery fins and sensing elements have been fitted and areundamaged;

(ii) that heater and cooler batteries, humidifiers, filters,silencers, fire dampers, sail switches, volume controldampers etc., are installed correctly in relation to air


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flow;

(iii) the damper free-movement, clearances seating pining todamper spindles, position of blades with respect toquadrant indication, relative positions of blades in multi-leaf dampers;

(iv) the control linkages on motorized dampers for alignment,rigidity, lubrication and free movement withoutslackness;

(v) that dampers throughout the system are secured in open position with damper actuators disconnected;

(vi) the free movement of fire dampers together with thelocation of, access to and fitting of, fusible link assembly;all fire dampers are finally secured in open position;

(vii) that all adjustable louvres are set without deflection, i.e.normal to face of grille. Adjustable cones on diffusersare set either all in the fully up or all in the fully down position;

(viii) that test holes are provided for measurement of total airflow.

4.5.2.3 Visual Checks for Air tightness

It is assumed that pressure testing of high velocity systemductwork is carried out during construction. This is essentialon all high velocity systems and is widely required for lowvelocity systems.

Check :

(i) the builders work ducts and shafts seals;

(ii) that access doors to plant equipment are sealed around

the whole periphery;(iii) the ductwork joints, including flexible couplings;

(iv) that inspection covers are fitted;

(v) that drain water seals are fitted;

(vi) that plugs or covers for test holes are fitted.

4.5.2.4 Mechanical Checks

4.5.2.4.1. Fans


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Check :

(i) the external cleanliness of fans;

(ii) that all components, bolts, fixing, etc., are secured;

(iii) that the impeller is secured, free to rotate, of correcthanding and correct clearances;

(iv) that axial-flow-type fans are installed for correct air flowdirection and, where compounded, in correct order;

(v) the level and plumb of fan and motor shaft and slide rails;

(vi) the anti-vibration mountings for correct deflection;

(vii) the static balance;

(viii) that the correct drive is fitted;

(ix) the securing and alignment of pulleys and couplings;

(x) the belt tension and match;

(xi) the cleanliness of the bearing;

(xii) that the lubricant is fresh and of the correct grade;

(xiii) that the coolant is available at bearings when specified;

(xiv) that drive guards are fitted and the access for speedmeasurement is provided;

(xv) for satisfactory operation of inlet guide vanes over fullrange of movement;

(xvi) that fan casings to be earthed are correctly and soundly bonded.

4.5.2.4.2 Automatic Fabric Filters

Check :

(i) the level mounting;

(ii) the alignment, clearances and free movement of spools,drives and limit switches;

(iii) the lubrication of spool drive motor, gearbox and spool bearings.

4.5.2.5 Electrical Checks


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Prior to the initial running of any electrical driven fan, electricair heater or automatically advancing filter, the following procedures shall be adopted :

4.5.2.5.1. With all Electrical Supplies Isolated

Check :

(i) the local isolation of motor and control circuits;

(ii) that there are no unshrouded live components within the panels;

(iii) that panels and switchgears are clean;

(iv) that the motor and surrounding areas are clean; air heaters

are clean;(v) that the transit packing has been removed from contactors

and other equipment;

(vi) that there is no mechanical damage to switchgears or airheaters;

(vii) that all mechanical checks on fan, motor and automaticfilter are completed (see para. 4.5.2.4);

(viii) that all connections are tight on busbars and wirings;

(ix) that the internal links on the starter are correct;

(x) that all power and control wirings have been completedin detail to the circuit diagram. (paying special attentionto circuits for star-delta connected, or specially woundedmotors);

(xi) that fuse ratings are correct;

(xii) that starter overloads are set correctly in relation to motorname-plate full load current.

(xiii) that the dashpots are charged with the correct fluid andthe time adjustments and levels are identical;

(xiv) that insulation tests on motor have been performedsatisfactorily;

(xv) that the adjustable thermal cut-outs are set correctly;

(xvi) that all cover plates are fitted.


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4.5.2.5.2. With Electrical Supply Available

a) Check that the declared voltage is available on all supply phases;

b) Where motor powers are substantial or reduced voltagestarting or complex interlocks are involved, the controlcircuit logic and the starter operation should be tested before the motor is rotated. The supply should first beisolated; then by the withdrawal of two power fuses orthe disconnection of cables followed by the reinstatementof supply to the control circuit alone, the control circuitshall be activated and starter operation observed. Adjustthe timers. Check for proper operation of all contactors,relays and interlocks. Finally open the isolators, reinstate power connections and close the isolators;

c) Where small motors have direct-on-line starting andsimple control circuits, the starter operation, etc., should be checked when first starting motor.

4.5.2.6 Electrostatic Precipitators

4.5.2.6.1 Before Approaching the Precipitator :

Establish :

(i) what isolators must be opened and fuses withdrawn tocompletely disconnect the precipitator plant from the lowvoltage supply. Beware of interlocking circuits which areenergized from elsewhere and where cannot be isolatedlocal to the precipitator;

(ii) the arrangements for preventing access to any highvoltage component until it is at zero potential;

(iii) adequatelabels for instructions / precautions / warnings to be deployed at the entrance access to the precipitator.

4.5.2.6.2 Low Voltage Electrical System

With all low voltage supplies isolated, check :

(i) the local isolation of all low voltage circuits;

(ii) that switchgears are clean and undamaged;

(iii) that the transit packing has been removed from contactorsand other equipment;

(iv) that all wiring connections are tight;


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(v) that all wirings have been completed in detail to circuitdiagram;

(vi) that all cover plates are fitted.

4.5.2.6.3. High Voltage Electrical System

Only a skilled and experienced person should be allowed toenter the precipitator casing; he should have with him theinterlock key which controls the opening of the access door tothe section of precipitator which he is entering or a fuse link orother item to prevent the precipitator being energized; a second person should be stationed outside the door as an observer andhe will normally also be in control of the operation of the power pack from this position. Before working on any precipitator system, any residual High Tension (H.T.) chargemust be removed using an earthing tool with insulated handle.

Where the power pack is remote from the precipitator, ashorting bar should be securely fixed between earth and eachH.T. feed to the precipitator.

The inbuilt features which prevent access to high voltagecomponents until at zero potential shall, without fail, bechecked as follows :

(i) no access to precipitator section via inlet or outletductwork connections. Where equipment is being usedas a barrier, beware of items which are demountablewithout tools such as pre-filter cells. Such items shouldalways be supplemented by safety screens as shoulddampers with blade width exceeding 100 mm;

(ii) any mechanical interlock correctly links H.T. circuits toearth before access door can be opened andsimultaneously de-energizes the H.T. primary circuit to prevent overload caused by the earth link;

(iii) no duplicate keys on site for the mechanical interlock

system;(iv) any safety switches fitted to access doors break the Low

Tension (L.T.) interlock circuit and destroy H.T. potential before the door is open wide enough to allow an arm orleg to reach a H.T. component within the precipitatorcasing; also check that switches are held positively opento prevent manual closure or closure by spring failurewhilst access door is open;

(v) check that H.T. potentials are reduced to a safe levelwithin the time it takes to open the door and reaches anyH.T. component. This will be of particular importancewhen door safety switches do not merely augment a


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mechanical interlock earthing system but are also the solesafety interlock, the value of bleed resistors connectedacross each capacitor holding H.T. charge will be critical;

(vi) a solid copper or aluminium bond connects the H.T. power pack and filter frame to the building main earthingsystem.

4.5.2.6.4 Cleanliness and Mechanical Condition

With all electrical supplies isolated, H.T. circuits earthed and precautions for staff adopted in accordance with para. 4.5.2.6.3.

Check :

(i) for unsafe ladders, walkways or dangerous projections;

(ii) the internal cleanliness of casing, components, includinginsulators and ductwork connections;

(iii) that all components are in place and correctly connected. No damage or distortion to ionizer and collector sections. No obvious foreign items in the precipitator cells.Ionizer wires of the correct diameter and type to be provided and to be correctly tensioned. Displacement ofthese wires from the centres between neutral electrodesshould not exceed 5% of the distance between the neutralelectrodes. No distortion of collector plates and gaps between plates shall not vary by more than 10%;

(iv) that the wash water and fluid coating systems arecompleted, reservoir is charged with correct fluid anddrainage systems are completed and free from blockage.Connection is provided for manual wash;

(v) that fabric filter sections are loaded with media; ifautomatic advancing then checks listed in para. 4.5.2.4.2shall be carried out.

4.5.2.6.5 Interlock Sequence and Alarm Systems

With electrical supply available check :

(i) that the precipitator interlock sequence is correct;

(ii) that all safety and failure alarm systems are functionedcorrectly.

4.6 Setting to Work & Balancing

4.6.1 Water Distribution System


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of a chilled water valve controller which is alreadysensing a low temperature, will not have the desiredeffect; provision of a local form of valve heat pressurisation must then be considered, such as a portableair compressor.

b) Open all control valves to full flow to heat exchangers of branch circuits.

c) Fully open the return and close the flow valve on the pump, close valves on standby pump. Closing the flowvalve on the duty pump will limit the initial startingcurrent, which is usually excessive at the first time a pump is running due to bearing stiffness.

4.6.1.4 Initial Running of Electrically Driven Centrifugal PumpSet

4.6.1.4.1 Initial Start

On activating the motor starter,

Check :

(i) that the direction and speed of rotation of the motor shaftare correct;

(ii) that the motor, pump and drive are free from vibrationand undue noise;

(iii) the motor starting current for sequence timingadjustment;

(iv) the motor running current on all phases to ensure thatthey are balanced between phases. The flow valve can beopened at this point to raise the running current to say 50 per cent of the name-plate full load current;

(v) that there is no sparking at the commutator or slip rings;(vi) that there is no overheating of the motor (see BS 587 and

BS 5000, Part II);

(vii) that there is no seepage of lubricant from the housing;

(viii) that the water flow to water-cooled bearings is sufficient;

(ix) the reduced speed and motor running current on multi-speed motors.

4.6.1.4.2 Initial Run


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a) A light load should be sustained until the commissioningengineer is satisfied from the checks listed in para.4.6.1.4.1 and from motor insulation test readings thatfurther load may be applied. Repetitive starting of themotor should be avoided to prevent over-stressing of thefuses, switchgear and motor.

b) Gradually open the discharge valve until the motorcurrent reaches either the design value or the motor fullload current, whichever is the lower.

c) Check the pump pressure developed by means of the pump altitude gauges against the design pressure. Ifexcessive pressure is developed at this stage, the causeshould be investigated.

d) Adjust the discharge valve so that the flow as determined

roughly from the pump characteristic is between 100 and110 per cent of the design value. Note that the motor fullload current is not exceeded.

4.6.1.4.3 Running-in Period

a) The pump should be run in accordance with themanufacturers recommendations and should be underfairly continuous observation. It should not be leftrunning outside normal working hours unless attended.During this time check that the bearings and motortemperature remain steady, that no noise or vibrationdevelops and that no bolts or fixing works loose.Observations may then become less frequent, but it isadvisable while later commissioning other parts of thesystem, to check the pump from time to time. During thefirst part of the running-in period :

(i) Vent all high points from time to time. When possiblethe medium should be heated to maximum permissiblelevels to assist in removing air from the heating system.

(ii) Adjust the gland nuts of the pump glands to give thecorrect drip rate. (Not applicable to mechanical seals.)

b) After eight hours of running, check all strainers. If theseare clean, regulation can commence. If they are dirty,clean the strainers, and run again for at least eight hoursand then re-check.

4.6.1.4.4 Standby Pump

On installations with a standby pump, this standby pumpshould also be commissioned. This pump can be checkedagainst the other and in the unlikely event of failure of the first


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pump, commissioning can continue using the second pump.However, a full diagnosis of the reasons for the failure of theduty pump must be made before energizing the standby pumpto ensure that any contributory causes are remedied.

4.6.1.4.5 Secondary Pump

In systems with primary and secondary pumps, starting procedures for the primary pumps should be dealt with first.Isolate the secondary system during this period to prevent anyaccumulated deposits not removed during the flushing process being carried over into the secondary services. After the finalcheck of strainers referred to in para. 4.6.1.4.3.b, the secondarysystem can be opened up and the starting procedure for thesecondary pumps initiated. Only after a final check of both primary and secondary strainers should actual regulationcommence.

4.6.1.5 Regulation of Water Flow

4.6.1.5.1 The procedures described in this section are a guide to the principles of regulation by proportional balance.Regulation is achieved by measuring the pressure dropacross a device with a constant flow coefficient capacityindex. Balance is obtained by varying the water flowacross the device so that the ratio of actual water flowrate to the design water flow rate (as calculated from thesquare law relationship of water flow rate to pressuredrop) is the same (or within designers tolerance) acrossdevices. The device may be a venturi-meter, an orifice- plate, a control valve with a known calibrated flowcharacteristic, a calibrated regulation valve or any devicewith a constant flow coefficient and a calibratedcharacteristic reliable as to accuracy and repeatability.Where valves are used they are used in the fully open position, i.e. as a form of fixed orifice. For greateraccuracy of absolute flow measurement, only devicescovered by British Standard BS 1042 (Measurement of

fluid flow in pipes) should be used.4.6.1.5.2 For the purposes of illustration of the procedures, the

system as shown in Fig. 1 of Appendix C will be used.Although the procedures are equally applicable to heatingand condensing water circuitry, a chilled water systemwill be used to illustrate the method. In the heatexchange processes in chilled water systems, temperaturedifferences between the two fluids are generally verysmall by comparison with heating systems and for thisreason the performance of terminal plant is considerablymore sensitive to any deviations from the design waterflow rate. Hence, the T & C procedure requires moreexacting tolerances when balancing this type of system.


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A series of branch circuits each with several loads have been indicated, flow to each load being controlled by athree-way control valve. Three-way valves in bothmixing and diverting applications plus a wild non-controlled coil have been included in the diagram todemonstrate the flexibility of the regulation procedures.In the system illustrated at Fig. 1 of Appendix C, the flowline to each terminal unit is fitted with aregulating/isolating valve which has in-built pressuretappings. This valve is used in its fully open position as afixed orifice device for water flow rate measurement.The flow measurement may be made anywhere in the branch circuit. A fixed orifice is sometimes incorporatedinto the regulating valve in the return line. The principleof the balancing method remains the same. The returnline from each terminal unit is fitted with a doubleregulating/isolating valve which is regulated and locked

in position during the balancing procedure. Where there-way valve is fitted, a double regulating/isolating valve isinstalled in the bypass, e.g. across the heat exchanger to balance the bypass with the coil.

4.6.1.5.3 Initial Check of System Water Flow Rates

a) Check the pressure drop across the associated flowregulating valve of each terminal unit by connecting amanometer between points a and b. (Refer to terminalunit A1 in Fig. 1 of Appendix C) It should beremembered that the reading obtained is related to thedesign water flow rate by a square law, not a linearrelationship. This can be represented by the followingexpression :

P1 Q12 P2

= Q22 . .. .. .. . W.1

Where :

P1 = Actual pressure drop .. .. kPa

P2 = Design pressure drop .. .. kPa

Q1 = Actual water flow rate.. .. m3/s

Q2 = Design water flow rate.. .. m3/s

Hence the actual percentage of design water flow rate obtainedcan be deduced from the following calculation :

Actual percentage of design water flow rate obtained


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P1 = P2 x 100.. .. .. .. ..W.2

b) Inspection of the percentages of obtained water flow rateto design water flow rate will indicate which is the leastfavoured (index) branch and which is the most favoured

branch.c) At this stage manually set the three-way valve to the

bypass position and regulate the bypass valve S so thatthe pressure drop between a and b equals the reading previously obtained with the three-way valve in the fullflow position. Lock the bypass double regulating valve.This procedure is not part of the balancing of the mainwater distribution system but is the local commissioningof the water flow control of the three-way valve.

4.6.1.5.4 Balancing of Terminals

Start to balance the most favoured branch. The water flow rateof each terminal unit should be balanced to the water flow rateof the index terminal unit in that branch. Each branch is dealtwith independently. (The main branch valves A, A, B, B, C,C in Fig. 1 of Appendix C are all fully open at this stage).Assume branch A-A has the highest unit A1 (remote inhydraulic terms relative to the circulating pump) is the leastfavoured. If it is not, connect one manometer across valve No.

1 and a second manometer across the regulating valveassociated with the least favoured terminal unit. Regulate thedown-steam double regulating valve No. 2 until the percentageof design water flow rate across the two valves are equal (orwithin the designers tolerances). Leaving the first manometerconnected across valve No. 1 (a and b) while the rest of the branch A-A is balanced. Connect the second manometeracross valve No. 3. Regulate valve No. 4 until the percentageof design water flow rate is the same (or within the designerstolerances) as valve No. 1. Repeat this procedure for all valveson branch A-A. Remove both manometers and start on thenext most favoured branch. Carry on until the water flow ratesof all terminal units on all branches are balanced within each branch.

4.6.1.5.5 Balancing of Complete Branches

For this stage, the branch regulation valves (A, B and C) will be the measuring stations. Check the percentage of designwater flow rate across each branch regulating valve. It willthen be apparent that which is the index branch (say A-A). Set

the first manometer across valve No. A and the secondmanometer across valve B until the percentage of design waterflow rates across the valves A and B are equal (or within thedesigners tolerances for branch balance). Leaving the first


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manometer connected across valve A, repeat this procedure forall branches (in this example for branch C-C) working backfrom the most remote branch to the branch nearest the pump.(Where, at the start of branch balancing, if the most remote branch is not the index or least favoured branch, it should bemade so, in the manner described for terminal balance.)

4.6.1.5.6 Secondary Mixing Set Regulating

For the purpose of illustration it is assumed that the designwater flow rate as delivered by the secondary circulating pumpis in excess of the design water flow rate of the secondarymixing three-way valve. The first manometer is connectedacross valve No. 11 and the second manometer across valve No. 14. With valve No. 13 fully open and the secondary three-way valve in the full flow position, the percentage of designwater flow rate through valve No. 11 should be in excess of the

percentage through valve No. 14. (Regulate valve No. 13 untilthe percentage of design water flow rate are equal (or withinthe designers tolerances). Manually set the secondary three-way valve to the bypass position and regulate valve No. 12until the percentage of water flow rate through valve No. 11equals the percentage obtained with the three-way valve in thefull flow position.

4.6.1.5.7 Secondary and Primary Final Regulation

Total water flow is measured by connecting a manometer (orother accurate measuring device) across the total flowmeasuring device such as an orifice plate or venturi meter. Thesecondary total water flow rate is regulated first by adjustmentof valve No. 15 until the pressure drop across the total flowdevice equals the design pressure drop. This procedure isrepeated finally on the primary circuit with the manometerconnected across the primary total flow measuring device andadjusting the double regulating valve No. 16. At this stage re-scan all the measuring stations for record purposes includingthe pump differential pressures and the evaporator pressure

drop and, where possible, check against the manufacturersdata.

4.6.1.5.8. Other Regulating Valves

Valves incorporating an integral orifice plate, double regulatingfacility and metering station as a single unit, or doubleregulating valve plus separate orifice plate and metering stationare also available, this eliminate the need for a regulating valvewith in-built pressure tappings. The T & C procedures would be similar but check with the manufacturer.

4.6.2 Air Distribution System


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4.6.2.1 Precautions Against Airborne Dirt

The system should have been cleaned internally in accordancewith para. 4.5.2.1 but further precautions shall be taken beforestarting the fans for the first time :

(i) disconnect final flexible connections to terminal unitssuch as induction units and blender boxes which aresusceptible to faulty operation through dirtiness;

(ii) preferably remove all high efficiency terminal filterswhich are susceptible to rapid choking;

(iii) check that suitable temporary protection has been provided for anything within spaces served by the systemwhich could be damaged by initial discharge of dust fromsupply outlets at first start-up;

(iv) install main inlet filter cells, properly coated as necessary,to avoid introducing additional dirt into the ductworksystem after start-up. Check seating of cells forairtightness. Commission automatic fabric andelectrostatic filters in accordance with para. 4.6.2.2 and4.6.2.3;

4.6.2.2 Automatic Fabric Filters

a) Preliminary checks in accordance with para. 4.5.2.4.b and4.5.2.5 shall have been completed.

b) Install filter media in accordance with manufacturersinstructions.

c) Energize the filter without air flow. With the differential pressure control device looped out, close the isolatorcontrolling supply to filter and test operation by themanual advance switch. Leave the filter on manualadvance until the correct total air flow is established

through the filter.d) The correct total air flow through the filter shall be

established as part of the procedure for regulation of airflow (see para. 4.6.2.5 below).

e) Commission the differential pressure controller afterestablishment of correct air flow as described in para.4.6.2.5.7 for which the clean filter condition willnormally have been manually selected. An inclinedmanometer with pressure sampling points adjacent to thefilter fabric will be used to measure the prevailing static pressure drop across the clean filter and this will berecorded. The filter may then be progressively blanked


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off (e.g. with cardboard) until the manometer indicatesthe design dirty filter pressure drop. The differential pressure control will be adjusted to start advancing thefilter at this dirty filter pressure drop and to stopadvancing the filter at the design clean filter pressuredrop.

4.6.2.3 Electrostatic Precipitators

Only a skilled and experienced person should be allowed toenter the precipitator casing; he should have with him themechanical interlock key which controls the opening of theaccess door to the section of precipitator which he is entering ora fuse link or other item to prevent the precipitator beingenergized; a second person should be stationed outside the dooras an observer and he will normally also be in control of theoperation of the power pack from this position. Before

working on any precipitator system, any residual H.T. chargemust be removed using an earthing tool with insulated handle.Where the power pack is remote from the precipitator ashorting bar should be securely fixed between earth and eachH.T. feed to the precipitator.

4.6.2.3.1 Preliminary Checks

Under no circumstance shall commissioning proceed until allchecks listed in para. 4.5.2.6 have been completed.

4.6.2.3.2 Water Wash and Fluid Coating Systems

a) Commission the wash and coating systems in accordancewith para. 4.5.1 and 4.6.1 Adjust sequence timers.

b) The precipitator should be washed prior to initialenergizing and if specified coated with fluid, allowingcorrect drainage periods to elapse. (Note : This may be amatter of hours.)

4.6.2.3.3 Automatic Fabric Filter SectionsCommission any automatic fabric filter sections in accordancewith para. 4.5.2.4.2, 4.5.2.5 and 4.6.2.2.

4.6.2.3.4 Initial Energizing of Precipitator Without Air Flow

(i) Check that no one is inside precipitator casing, thataccess doors are closed and that no entry can otherwise be made to the precipitator interior.

(ii) Cancel and lock out any remote control system for precipitator.


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(iii) Switch on precipitator.

(iv) Check that there is no flash-over problem and thatindications from meters and lamps on precipitator control panel are normal. Faulty operation at this stage will probably indicate that a preliminary check has beenmissed or that water is still present from the initial wash.All safety measures listed in para. 4.5.2.6.3 must beimplemented before entry to the precipitator casing.

(v) Restore full automatic control sequence ready for theestablishment of air flow through the precipitator.

4.6.2.3.5 Application of Air Flow to Precipitator

When air flow is established through the precipitator (see.4.6.2.4.5) :

a) check that there is no excessive flash-over (say, anaverage of over five per minute per square metre of theface area). This may be caused, for example, by the lackof correct pre-filtration, no lint screen etc., in main orrecirculation ducts, presence of water, incorrect airvelocity or excessive H.T. voltage;

b) an inspection should be made of the de-energized precipitator after a few hours operation with air flowestablished (see para, 4.6.2.4.5). Absence of dirt stainingon any ionizer neutrals, etc., may indicate H.T.disconnection;

c) the H.T. voltage shall be checked at ionizer and collectorsections. Unless otherwise specified the H.T. voltageshould be within +3% of the nominal figure specified atthe mean declared L.T. voltage. Polarity should normally place positive voltage on the ionizer section to limitozone generation. Measurement of H.T. voltage shall be by means of an instrument comprising high stability

resistance chain with high sensitivity milliammeter inseries, or electrostatic voltmeter across one section of thechain. Only a skilled and experienced operator shouldattempt measurement of H.T. voltage. Great care isnecessary to avoid contact with live parts of the meterand no part of the meter or its connections should betouched when it is connected to H.T. components; anysuch connections should normally be in special H.T.cable to avoid current leakage. Readings should normally be made with the meter placed within the precipitatorcasing and observed from the outside through theobservation window;

d) the correct total air flow through the precipitator shall be


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established as part of the procedure for regulation of totalair flow (see para. 4.6.2.5.7);

e) the uniformity of air velocity distribution across the faceof the de-energized precipitator bank should be checkedusing an anemometer, after the regulation of total air flow(see para. 4.6.2.5.7);

To do this, it will be necessary to override the interlockwith the supply fan. It is important to ensure that the precipitator is cleaned and washed before operating thefan with the precipitator de-energized;

f) single point measurements of indicated velocity should be made at the centre of each 300 mm square of the facearea, and where appropriate instrument correction factorsshall be applied to each of the readings. The mean

indicated velocity is then calculated and each of the pointreadings is expressed as a percentage of this mean. The percentage variations of velocity must be within thetolerances specified. Upper limits will always be criticaland lower limits also in the case of agglomerator/storagetype units. Any failure to meet the specified tolerancesmust be rectified.

4.6.2.4 Initial Running of Electrically Driven Fan Set

4.6.2.4.1 Limit the Load

Wherever possible the first start of any motor should be onlight load. With centrifugal fan sets this will normally beachieved by limiting the mass flow by operation of the maindamper; a knowledge of the fan characteristic is required sothat excessive suction or delivery pressures are not applied tothe ductwork system.

4.6.2.4.2 Initial Start

On activating the motor starter, check :(i) that the direction and speed of rotation of motor shaft are

correct;

(ii) that the motor, drive and fan are free from vibration orundue noise;

(iii) the motor starting current for sequence timingadjustment;

(iv) the motor running current on all phases;

(v) that there is no sparking at commutator or slip rings;


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(vi) that there is no overheating of motor (see BS 587 and BS170);

(vii) that there is no seepage of lubricant from the housing;

(viii) that there is no overheating of the bearings;

(ix) that oil rings are running freely;

(x) the reduced speed rev/s and the motor running current onmulti-speed motors;

(xi) the rev/s of fan and motor;

(xii) the performance of fan belts in case of abnormalvibration.

4.6.2.4.3 Initial Run

A light load run shall be sustained until the commissioningengineer is satisfied from the checks listed in para. 4.6.2.4.2above and from motor insulation test readings that further loadmay be applied. Repetitive starting of the motor should beavoided to prevent over-stressing of fuses, switchgear andmotor.

4.6.2.4.4 Start at Normal Load

Subsequent to the satisfactory conclusion of the initial lightload run, the machine shall be stopped and restarted at normalstarting load, and the checks listed in para. 4.6.2.4.2 repeated.Again avoid repetitive starting.

4.6.2.4.5 Running-in Period

After a short run at normal load (a few minutes run willnormally suffice) flexible connections to terminal units, etc.,

and terminal filters (which were removed in para. 4.6.2.1) shall be restored to position. Subsequently a running-in period shall be sustained until the fan set is in a reliable continuous runningcondition that can safely be placed under the normal operationand maintenance regime. The regulation of the air distributionsystem shall be delayed until the running-in period (which maylast some days) is completed satisfactorily. During therunning-in period the following work shall be conducted;

a) the dynamic balance of the fan and motor shall beinvestigated and correct if necessary;

b) the performance of electrostatic precipitators shall bechecked (see para. 4.6.2.3).


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4.6.2.5 Regulation of Air Flow

Regulation of air flow shall be carried out in accordance withthe following procedure. It is applicable to all air distributionsystems which require manual regulation, including inductionunit systems. Only the method of measurement of air flow atthe terminals is particular to the type of system involved.

4.6.2.5.1 Principles

The method consists essentially of working back to the fanfrom the remote branches by setting the correct proportional airflow at each junction of the system in turn (without regard forabsolute values of air flow) and so balancing the system. Thisdone, the absolute valves of air flow throughout the system are

then brought to their design values simply by adjusting themain damper only (next to the fan) until the design total airflow rate is established at the fan.

This theme is illustrated by consideration of air flow at the junction PQR in a system AZ as shown in Fig. 2 Appendix C.Q is a dampered branch on the duct RP and the required designvolumetric air flow rates are shown. With damper Q fully openwe may find by measurement that P handles 1.7 m3/s, Qhandles 1.3 m3/s; 50% and 75% of their design air flow ratesrespectively. To balance this junction we would close damperQ until P and Q handle the same proportion of their respectivedesign air flow rates : this may result in a balance of P handling2.0 m3/s (60% of its design) and Q handling 1.0 m3/s (60% ofits design). It follows that B will now be handling 60% of itsdesign rate also, i.e. 3.0 m3/s.

Now that damper Q is set, provided that we do not alter anydampers in the system QB downstream of Q or in the systemPA downstream of P, we know that whatever the absolutevalue of air flow at R, this air flow will be divided into the

correct design proportions between P and Q at this junctionPQR, i.e. two-thirds to P and one-third to Q.

As we work back up the system towards the fan, adjustingdampers at other junctions between R and the fan, we will bechanging the absolute values of flows in R, P and Q but not theratios of those flows which remain 3:2:1. Ultimately, when allthe junctions have been balanced, we will adjust the maindamper to obtain the design absolute air flow rate in the mainduct from the fan. The correct total air flow will not be divided by the system as set in the correct proportions at eachsucceeding junction, until R is reached where 5.0 m3/s will beflowing; this will now divided into 3.3 m3/s in P and 1.7 m3/sin Q exactly as required by the design.


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One final point to note is that in practice, when balancingsuccessive junctions, a particular routine is adopted both toavoid accumulative errors and to avoid the need for test pointsand dampers in ducts between junctions. Referring to Fig. 3 ofAppendix C, when A, B have been balanced, A, B and C are allhandling the same proportion of their respective design air flowrates. Thus when we come to balance the junction CDE, D can be balanced against A or B and not only against C. In practiceA is usually selected as the reference point and the air flows inB, D and F are in turn balanced against the air flow in A.

Adjusting the distribution dampers to obtain a proportional balance only, has the important implication that a knowledge isnot required at this stage of the absolute values of air flow ratein any part of the system. Hence, the instrument used formeasuring the air flow at the terminals or branches of a

distribution system needs not necessarily indicate the true valueof air velocity or pressure. Therefore, inherent errors in theinstrument causing a consistently higher or lower velocityreading than the true value can be ignored; also provided thatthe same method of measurement is used, factors such as thosefor effective grille areas are usually self-cancelling and can bedisregarded.

Not until the entire distribution system has been proportionally balanced will it be necessary to establish the absolute value ofthe system total air flow rate.

4.6.2.5.2 State of the System and Building

Before starting the regulation of air flow, it is essential that thefollowing conditions are fulfilled :

(i) the building is completed and windows and doors areopened or shut consistent with their normal state; (refer to para. 4.6.2.5.2.v);

(ii) the duct system is complete and leak-free and in the caseof high velocity systems pressure testing is satisfactory;

(iii) the requirements of checks listed in para. 4.5.2 have beenmet;

(iv) normally all main and branch heaters and coolers onsupply systems shall be shut off but on all fresh airsystems, some heating or cooling may be applied to themain duct only (which handles the total air flow) in orderto temper the air delivered to the spaces. Heat gains andlosses to the ductwork can be minimized by restrictingthe difference between duct air temperatures and ambienttemperatures;


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(v) any associated air supply or extract systems which havenot been regulated should normally be shut down. For balanced systems it may be necessary to balance supplyand exhaust individually against atmosphere (i.e. withdoors open), then operates them together for regulation oftotal system air flow.

4.6.2.5.3 Preliminaries to Regulation

To illustrate the regulation procedure a diagram (Fig. 4 inAppendix C) of a typical low velocity supply air system is provided. Note, however, that the procedure for other types ofsystem, including extract systems, is identical to that describedhere :

a) Check that the dampers on all terminal grilles or diffusers1, 2, 3, 4 etc., are fully open; also that sub-branchdampers AA, AB, etc., branch dampers A, B, C and maindamper M are fully open. All adjustable louvres should be set without deflection, i.e. normal to face of grille. Alladjustable cones on diffusers should be set either all inthe fully up or all in the fully down position. Setautomatic plant mixing dampers FA and RC to oneextreme position, i.e. normally either full fresh air or fullrecirculation.

b) Measure fan motor amps. Throttle main damper M ifnecessary.

c) Measure the indicated air flow rates at all terminal grillesor diffusers 1, 2, 3, 4, etc., preferably using oneinstrument. Express these initial measurements asIndicated percentages of design air flow. It is importantthat the design air flow rates (with which the measuredair flow rates are compared) are all based on a commondatum of density, usually that of Standard Air or

occasionally that of air at design density at fan inlet;during these initial measurements air must be of constanttemperature throughout the distribution system (see para.4.6.2.5.2.iv) although this temperature datum need notnecessarily equate with the density datum adopted for thedesign values of air flow. Note also that variations inwind, stack effect, fan motor voltage, filter resistance,etc., will all have some effect on the performance of thesystem; for this reason these initial measurements (andalso the final measurements, see para. 4.6.2.5.3.d) will bemade in one quick, continuous operation so that thereadings will normally be truly comparable.

d) Study the general pattern indicated by the initial readings.


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The principal points of interest are :

(i) If the indications are that the total air flow rate handled by the system is less than 100% of the design then physical changes to the air handling system will probably be necessary before regulation can begin. The fan performance curve and a measurement of fan motorcurrent will assist in assessment of the total air flow.

(ii) Are there any obvious faults such as design errors, blockages or leakages indicated, for example, by largedifferences of air flow readings between apparentlysimilar branches and terminals? Such faults will requiredcorrection.

(iii) What are the indicated values of air flow in each branchA, B, C and each sub-branch AA, AB, etc., of the

system? (obtainable by totalling appropriate sub-branchvalues). This will usually determine the order in which branches and groups of terminals are tackled in theregulation procedure.

(iv) What is the location of the least favoured terminal (i.e.the terminal with the lowest percentage of design airflow) on which sub-branch AA, AB, etc., of the system?This information is necessary for the regulation ofterminals.

4.6.2.5.4 Regulation Procedure

a) On any one branch, A, B, or C of the system, the first taskis to regulate the terminal dampers on that branch. Theorder in which this work is tackled will normally bedecided from the initial readings described in para.4.6.2.5.3. The branch A, B or C which has the highestindicated percentage of design air flow will be identifiedas, say, C and normally tackled first; on that chosen branch C, the Sub-branch with the highest indicated

percentage of design air flow will be identified as, say CEand the group of terminals No. 101 to No. 107 on thatsub-branch CE will normally be regulated first. Next thegroup of terminals on the sub-branch with the secondhighest indicated percentage of design air flow, say, CD,will normally be regulated and so on working towards thesub-branch of the branch C which had the lowestindicated percentage of design air flow during the initialreadings. By working in this order measurements of airflow at terminals will be made usually at values whichare as near as possible to the design values of air flow.Also, this order of work will give the earliest possibleindication that any branch with low initial flow is notgoing to reach ultimately the design performance


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required; thus, if necessary, the designer can define physical changes to the system or revise tolerances on airflow without delay.

b) For the regulation of terminal dampers, the group ofterminals on each sub-branch of the system will betreated independently of groups of terminals on their sub- branches. Thus on sub-branch CE, dampers on terminals No.101 to No.107 will be adjusted to obtain the sameindicated percentage of design air flow at each of theterminals within this group No.101 to No.107. (This percentage could be, say, 130%.) On sub-branch CD thedampers on terminals No.94 to No.100 will be adjustedto obtain the same indicated percentage of design air flowat each of the terminals within this group No.94 to No.100. (But this percentage could be, say, 110%).During the regulation of groups of terminals, all the sub-

branch dampers (and the branch dampers) will be leftuntouched in the original fully open position.

c) When all the groups of terminals on this chosen branch Chave been adjusted in this way, the next task is to regulatethe groups of sub-branch dampers CA to CE on this one branch C only. The sub-branch dampers CA to CE will be adjusted to obtain the same indicated percentage ofdesign air flow at each sub-branch within this group CAto CE. Now for the first time each terminal on branch Cwill be handling the same percentage of design air flowas every other terminal, in whatever group, on branch C.

d) When the regulation of both terminals and sub-branchdampers on branch C has been completed, the branchwith the second highest indicated percentage of design airflow will be identified from the initial readings as, say, Band the procedure described in para. 4.6.2.5.4.a and4.6.2.5.4.b repeated for this branch and so on for anyother branches leaving the branch with the lowest initialindicated percentage of design air flow (in our case

branch A) to the last. Note that through out this procedure branch dampers A, B and C are all leftuntouched in the fully open position.

e) When the regulation of terminal and sub-branch dampershas been completed on all branches, the next task is toregulate the branch dampers A, B and C to obtain thesame indicated percentage of design air flow in each branch (this could be, say, 115%). Now for the first timeeach terminal on the entire system will be handling thesame percentage of design air flow as every otherterminal in the entire system, i.e. 115% throughout.

f) Finally, when the regulation of all branch dampers has


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been completed, the main damper M will be adjusted toobtain the desired absolute air flow in the main duct.

Each stage of the regulation procedure outlined above isdescribed in detail in the following para. 4.6.2.5.5 to4.6.2.5.8.

Note that the order of working suggested is usually the best one but if necessary a different order can be adopted provided that a basic rule is not broken : at any junctionin the system (e.g. the junction of terminal with sub- branch or sub-branch with branch, etc.) no damper, whichregulates the air flow to one arm of that junction, shall beadjusted until all dampers on either arm downstream ofthat junction (in the case of a supply system, butupstream of that junction in the case of an extract system)have been adjusted. For example branch damper C shall

not be adjusted until branch dampers A and B and sub- branch dampers CA, CB, CC, CD and CE have all beenadjusted; and again sub-branch damper CE shall not beadjusted until terminal dampers No.101 to No.107, sub- branch dampers CA, CB, CC and CD have all beenadjusted; and again termin.al damper No.107 shall not beadjusted until terminal dampers No.101 to No.106inclusive have all been adjusted, etc

Note also that the procedure is normally broken downinto a series of self-contained operations e.g. one groupof terminals is balanced without relation to conditionselsewhere in a large system perhaps on another day.Thus the errors in regulation work due to the effect, overa prolonged period, on system performance of variationsin filter resistance, wind effect, stack effect, etc., areminimized. Furthermore, errors due to shorter termvariations, for example an instantaneous change in fanmotor voltage, are minimized by regulating the air flow ateach branch or terminal to balance proportionally withthe current air flow at the reference terminal.

4.6.2.5.5 Regulation of Terminal Grilles, Diffusers and Units

Assume it has been decided, in the way described in para.4.6.2.5.4, to start regulation of terminals at the group No.101 to No.107 on sub-branch CE. The least favoured terminal on thissub-branch has been located (see para. 4.6.2.5.3.d). If thisterminal is No.101, the end grille, diffuser or unit, then proceedas follows :

(i) Measure the indicated air flow at No.101 terminal whichwill be used as the reference terminal for this group.Express this measurement as indicated percentage ofdesign air flow rate. This percentage will be used as the


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lower balancing limit for this group of terminals.

(ii) With the same instrument and using the same method,measure the air flow at terminal No.102 and express thisalso as indicated percentage of design air flow.

(iii) Compare the indicated percentages of design air flow at No.101 and No.102.

(iv) If the indicated percentages of design air flow at the twoterminals are within the tolerances specified, the damperson these two terminals will require no adjustment.

(v) If the indicated percentages of design air flow is outsidethe tolerances specified, close the damper on terminal No.102 by a judicious amount.

(vi) Measure the indicated air flow now at No.102 andexpress this as an indicated percentage of design air flow.

(vii) Return to No.101 and measure the indicated air flow nowat No.101. Again express this as an indicated percentageof design air flow.

(viii) Compare the indicated percentages of design air flownow handled by No.101 and No.102.

(ix) If the indicated percentages of design air flow at the twoterminals are now within the tolerances specified, theterminals are now in balance and the dampers on thesetwo terminals will hence-forward require no furtheradjustment.

(x) If the indicated percentages of design air flow are still notwithin the tolerances specified, make a further carefuladjustment of No.102 damper, take new readings ofindicated air flow at No.102 and No.101 and make afurther comparison.

(xi) With practice an operator will normally achieve a balance by one adjustment of No.102 damper. The rule is toclose No.102 damper by the least amount necessary to bring the indicated percentage of design air flow at No.102 below the upper balancing limit when comparedwith the reference terminal No.101. By avoiding over-dampering at terminals the rise in air flow at No.101 iskept small, making it easy to judge the value to whichother terminals should be regulated.

(xii) When No.102 has been regulated to balance with No.101(the reference terminal), balance No.103 terminal againstthe reference No.101 in the same way.


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(xiii) The terminals No.104, No.105, No.106 and No.107should be regulated, in turn, to balance with No.101 untilevery terminal on that sub-branch CE has been regulatedto balance with No.101; all terminals within this groupare now in balance with each other within the tolerancesspecified and need no further adjustment.

(xiv) Note that a change in position of damper No.103 has lesseffect on the air flow at No.101 (and No.102) than achange in position of damper No.102 would have on theair flow handled by No.101. Therefore, as we proceedfurther away from No.101, the reference terminal,towards the fan during the course of the regulation procedure, the effect which the closing of a terminaldamper has on the air flow at the reference terminal (andall other terminals already regulated) progressively

diminishes and it quickly becomes unnecessary tomeasure the air flow at the reference terminal in everycase after a terminal is regulated.

(xv) Where the least favoured terminal on the branch is not No.101, but some intermediate terminal, close No.101damper until it is the least favoured (checking No.101against the intermediate terminal which was the leastfavoured), then regulate as described in para. 4.6.2.5.5.ito 4.6.2.5.5.xiv, using No.101 as the reference terminal.

(xvi) Regulate the terminals on each of the other sub-brancheson this branch C using the above procedure. Note thatthe terminals on any one sub-branch will be treated as anindependent group and will be regulated to balance with areference terminal within the group, e.g. on sub-branchCD, terminals No.95 to No.100 will be regulated to balance with reference terminal No.94. Throughout this procedure the sub-branch and the branch dampers will allleft untouched in the fully open position.

(xvii) The group of terminals on each sub-branch is not in astate of proportional balance within the requiredtolerances. The next step is to regulate the sub-branchdampers in order to bring all the sub-branches on branchC into balance with each other within the requiredtolerances.

4.6.2.5.6 Regulation of Sub-branches and Branches

The method used is similar to that for the regulation ofterminals (see para. 4.6.2.5.5).

a) Measures the indicated air flow handled by each of thedampered sub-branches CA to CE and express this as an


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indicated percentage of design air flow. Wherever possible establish this percentage by measuring theindicated air flow from one typical terminal on each sub- branch. The typical terminal selected shall preferablyexhibit a uniform and stable air flow pattern. Only wherethe type of terminals on some sub-branches differs fromthe type of terminal on other sub-branches willmeasurement of duct air flow have to be made on asample of the sub-branches which have different type ofterminal, so that indicated air flow rates at the differingtypical terminals may then be compared.

b) Regulate the sub-branches CA to CE by applying thesame procedures described in para. 4.6.2.5.5, i.e. byconsidering each sub-branch as a terminal grille on the branch duct C, but using closer balancing tolerances. Thesub-branch CA will be used as the reference sub-branch

for this operation in exactly the same way that terminal No.101 was used as the reference terminal for theregulation of terminal No.101 to No.107.

Note that throughout this procedure the branch damper Cis left untouched in the fully open position. At theconclusion of the work, the sub-branch dampers will have been adjusted to achieve the same indicated percentage ofdesign air flow (within the tolerances specified) in eachof the sub-branches CA to CE.

c) When the regulation of both terminal and sub-branchdampers on branch C has been completed, the next branch, in our case branch B, chosen in the way describedin para. 4.6.2.5.4 will be tackled. Once again the firsttask here is to regulate the groups of terminals on this branch as described in para. 4.6.2.5.5, subsequently toregulate the sub-branch dampers as described in para.4.6.2.5.6.a and 4.6.2.5.6.b. This procedure will berepeated for all branches in turn, leaving the leastfavoured branch (in our case branch A) to the last.

During this work branch dampers, A, B and C are leftuntouched in the fully open position.

d) When the regulation of both terminals and sub-branchdampers has been completed on all branches, the branchdampers A, B and C will be regulated to achieve the same percentage of design air flow at each branch. The methodused will be that described for the regulation of sub- branches in para. 4.6.2.5.6.a and 4.6.2.5.6.b, i.e. each branch of the system will be though of as a terminal grilleon the main duct and the procedure described in para.4.6.2.5.5 adopted. Once again, wherever possible,establish the indicated percentage of design air flow ateach branch by measuring the indicated air flow from a


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typical terminal on that branch. The branch A will beused as the reference branch for the regulation procedurein exactly the same way that terminal No.101 was used asthe reference terminal for the regulation of terminal No.101 to No.107. During this work the main damper Mwill be left untouched in its original position. Allterminals, on whatever branches or sub-branches, arenow in a state of proportional balance within thetolerances specified and it only remains now is toregulate the main damper M to achieve the correctabsolute air flow rates to all parts of the system.

4.6.2.5.7 Regulation of Total Air Flow Rate

a) Measure the absolute value of the total air flow rate with pitot tube and manometer, preferably in the main duct.Where a reliable reading cannot be obtained in the main

duct, the total air flow can be established by adding the branch (or zone) air flow rates which in this instanceshall be measured by pitot tube and manometer.

b) Compare the measured total air flow with the designvalue. If necessary adjust main duct damper M until themeasured value is within the tolerances specified on thedesign value of total air flow. Record in full the resultsof the final measurement. Also measure and record thesupply voltage to the fan motor, the motor current and thefan revolutions per second at the time of this finalmeasurement of air flow.

Note that with systems which contain fabric filters, ormore particularly absolute filters, the dirtiness of the filtermay have a significant effect on the total air flow rate.Since the clean filter condition is the only state which can be readily identified and selected on site, measurementsof total air flow should be made with filters cleanwherever possible and the results obtained should becompared with the design values at this clean filter

condition. The static pressure drop across the clean filtershall be measured at the time of the final measurement oftotal air flow rate and recorded. Differential pressurecontrols for automatic fabric filters shall now becommissioned in the way described in para. 4.6.2.2.e

c) Where the plant contains auto-dampers for variable proportions of fresh/exhaust/recirculation or face and bypass air proportions, the total air flow measurement andthe main damper regulation shall be conducted with theauto-dampers at one extreme of the auto-cycle. It may benecessary to adjust the auto-dampers to obtain the correct proportions of fresh/exhaust/recirculation or face and bypass air when regulating the total air flow. The


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proportions and the total air flow handled at the otherextreme of the auto-damper cycle must then beinvestigated and if necessary adjustments will have to bemade to the proportions at this end of the cycle, whilstmaintaining constant total air flow. The characteristics ofthe auto-dampers will of course determine what change,if any, in total air flow occurs at intermediate damper positions.

Note that wherever one air handling system is directlyconnected with another system, for example, a supplysystem connected with an extract system via arecirculation duct with fixed or variable mixture dampers,then first proportionally balance the distribution networksof both systems in turn, finally regulate the total air flowin both systems, and the proportions offresh/exhaust/recirculation air in one combined operation.

d) When the regulation of total air flow is complete, all branches and terminals on the system will be handling therequired absolute air flow rates within the sum of thetolerances accumulated during the balancing procedure.

e) The uniformity of air velocity distribution across the faceof electro-static precipitators shall now be checked (see para. 4.6.2.3.5.e and 4.6.2.3.5.f). Using the sametechnique the air flow distribution at ducted heating andcooling coils may also now be checked.

4.6.2.5.8 Conclusion to Regulation

a) Normally after a satisfactory total air flow has beenestablished and recorded, a final check shall be made toensure that all terminals are in satisfactory balance withinthe tolerances specified, by measuring in one continuousoperation the indicated air flow rates at all terminals,grilles, etc., preferably using one instrument, and byexpressing these measurements as indicated percentages

of design air flow. Where there are more than one typeof terminal on the system, the appropriate factors must beapplied to the readings so that they are all on acomparable basis. The results obtained are not, ofcourse, absolute rates of air flow at terminals - they aremerely indicative of the degree of balance between alloutlets. However, taken with a leak-free distributionsystem a satisfactory balance at terminals is a proof thatthe system has been correctly regulated, and that theterminals are handling the correct absolute air flow rates,(Note : do not make random alterations to dampersettings in an attempt to correct any mistakes; anycorrective action will require careful planning tominimize the amount of rebalancing needed).


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b) After a satisfactory check on system balance, scribe the position of all manual damper operating arms and, preferably, lock them.

c) Finally, adjustable louvres and cones on outlets, grillesand diffusers shall be set to positions predetermined andspecified by the designer.

4.6.2.6 Dual Duct System

a) Dual-duct systems are sometimes designed to handle 85to 100% of the total systems air supply through the coldduct and from 40 to 80% through the hot duct. Balanceshould be accomplished as follows :

(i) Set all room control thermostats for maximum cooling,

this fully opening the cold air valves.(ii) The equipment and main ducts should be checked as

outlined in para. 4.5.2.1 and 4.6.2.5

(iii) Determine if the static pressure at the end of the system(the longest duct run) is at or above the minimumrequired for mixing box operation. Proceed to theextreme end of the system and check the static pressuredrop across the box with an inclined draft gauge ormagnehelic gauge. The drop across the box should eq

testing & commissioning procedure hvac

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