2 Overview

Commissioning Personnel

2.1 No single person can master all commissioning techniques; a commissioning team is therefore often formed, the purpose of whose work is to ensure that the plant can meet the necessary normal operating and safety requirements.

2.2 The large quantity of data generated during commissioning will become valuable reference material relating to the plant for the future; it must therefore be ensured in principle that these data are collected together in the form of a commissioning manual and, after completion of the contract, handed over to the owner together with the installation diagrams.

2.3 For commissioning to be completed smoothly, commissioning work must begin before actual completion, because many components of the system are com-

1) Standard contracts for the maintenance, inspection and related minor repair work of technical equipment in public buildings, drafted and published by the administration of the national or local mechanical and electrical engineering sector (AMFU), Bonn, 1995. become increasingly difficult to access after completion of the work. The correct installation of these components needs to be verified. As part of the installation procedure, leakage tests should be carried out. Failure to carry out commissioning work in a timely manner may delay completion of the project or result in unsatisfactory operation of the plant.

Commissioning Summary

2.4　The commissioning team should obtain detailed information from the system designer, including:

a. A "user" profile, including installation instructions and the design operating mode.

b. Design data on air movement, room static pressure, supply and extract air flow rates, and acceptable tolerances.

c. Winter and summer, indoor and outdoor design conditions, including detailed information on the guaranteed control method.

d. Manufacturers' model test data for the plant, together with commissioning, operation and maintenance instructions.

e. Relevant drawings showing the system layout, air flow test points, regulating damper positions, the positions of regulating devices and filters, and the sizes of ducts and terminal units. Considerable time can be saved if these drawings indicate the design air velocity and static pressure at each branch and outlet.

f. Wiring diagrams for all electrical equipment associated with the air-conditioning system, including motor control circuit information and wiring diagrams for interlocks and safety devices, such as emergency stop buttons located adjacent to the plant.

2.5　The CIBSE Commissioning Code, Code A "Air Distribution", provides all the specification information required by the commissioning team.

2.6　The designer should specify the types of test instruments and the test procedures. He should also state in the contract documents the accuracy requirements for the test instruments, and provide, for reference, certification documents issued by a testing centre.

2.7　On completion of the system, it should be capable of being trial operated by the contractor as a whole, and should pass the performance tests in accordance with the contract requirements.

2.8　The commissioning procedures should be carried out in the sequence set out in this document. That is, after completion of the static tests and inspections described in Chapter 3, the dynamic tests specified in Chapter 4 should be carried out, followed by the performance tests listed in Chapter 5, and finally the handover procedures described in Chapter 6.

2.9　Once it has been demonstrated that the system achieves the original design intent, the handover procedures should be completed. However, if the performance fails to meet the requirements, the matter should be dealt with in accordance with the provisions of the contract.

3　Pre-Commissioning Tests

3.1　Pre-commissioning tests include inspection, manual operation of plant, static tests and functional tests of individual components. These tests should be started before the system is put into operation and before the dynamic commissioning work specified in Chapter 4 of this document.

Installation Standards

3.2　The following must be verified during installation of the system:

a. The plant has been positioned and installed, and the installation has been carried out in accordance with the design specification and drawings.

b. Only approved sealants have been used during installation.

c. All components function correctly.

d. Access doors and inspection openings are sealed to a satisfactory standard.

e. Pressure tests and leakage tests on the ventilation ductwork have been carried out in accordance with the method specified in HVCA DW/143 "Ductwork Leakage Testing"; the tests are normally carried out on a section of ductwork after installation and before insulation. The test results must be recorded in the commissioning log book.

f. The gaps around doors and openings must comply with the design requirements.

g. Pressure relief valves, pressure balancing valves, regulating dampers, shut-off dampers and non-return valves operate correctly.

h. Test points are located at the designated positions and sealed with gasketed screws.

i. The control dampers have been correctly set, and the quadrant plates are correctly fixed.

j. The interlock devices are operational and comply with the relevant instructions.

k. The electrical circuits have been completed, successfully tested and energised.

l. The motors have been inspected, and the direction of rotation is correct.

m. The temperature and pressure of the cooling and heating media supplied to the plant achieve the specified flow rates. n. All air conditioning components and control functions meet the requirements.

o. The interlock devices and safety control operations of the air conditioning equipment meet the requirements.

p. The units are fully equipped, the insulation work is completed, and all air ducts and water pipes are labeled as required.

q. The building housing the ventilation units has reached a condition in which commissioning and performance testing can be carried out, i.e., the doors, windows, and walls have been completed and the surfaces have been finished with topcoat.

r. The areas around the ventilation units and the air supply locations are clean and tidy.

s. Access to all system components is safe and meets the requirements.

Installation Cleanliness

3.3 During installation, it must be confirmed that the ductwork installation achieves the "advanced level" specified in DW/TM2. DW/TM2 is published by HVCA under the title Guide to Good Practice — Internal Cleanliness of New Ductwork Systems.

3.4 Regardless of whether there is any doubt about the measurement specified in this document, the ductwork must be cleaned internally so that it meets the standard requirements again before being put into use.

3.5 The surfaces of "building fabric" ducts constructed of brick or concrete must be tightly sealed to prevent the emission of dust before use.

3.6 Fresh air intakes must be cleared of refuse, waste, construction debris, or any other potential sources of contamination.

Product Certificates of Conformity

3.7 The following certificates of conformity shall be collected and organized by the commissioning team and kept readily available for inspection throughout the contract construction period. They will form part of the handover documentation and be included in the commissioning manual.

a. Fan models and certificates of conformity.

b. Pressure test conformity documents for the following components: heaters; chilled water coils; humidifiers (if any).

c. Type tests of silencers.

d. Type conformity documents for coarse and medium-efficiency filters.

e. Individual conformity documents for high-efficiency (HEPA) filters.

Instrument Testing

3.8 Before the system is started up, the following items must be verified, and the tests must be carried out in detail as specified.

Air Filters

3.9 The quality of the filter housings, and especially of the gaskets, is critical to maintaining the effectiveness of the filtration system and ensuring that air does not leak through the filters. For this reason, the following tests shall be carried out.

a. The filter gaskets are securely installed and well maintained.

b. The filters are installed according to the direction of airflow.

c. Bag filters are installed with the bags vertical, and the bag shape is kept in good condition.

d. High-efficiency filters are installed in sealed housings; where required, the gaskets are tested in accordance with DIN1946.

e. Each filter is tested to ensure that its surface is undamaged.

f. Pressure gauges are installed to measure the pressure differential across the filters, and the initial and final filter resistances are recorded.

Drainage System Layout

3.10 All aspects of the drainage system comply with the provisions of the HTM "Design Considerations" and must be checked.

a. Drain pans are easy to remove.

b. Water seals have been installed and are easy to remove.

c. The drainage system is fitted with an "umbrella"-shaped air vent.

d. The drain pipes are securely supported without reducing the size of the air vent.

e. Each drain pan branched from the drainage system is connected individually to the air vent.

f. The operation of the drainage system is verified by introducing water into the drain pipes and drain pans to check whether all the water can be drained away. This test is carried out at normal speed and at half speed, and after the fans have been commissioned, it is repeated at reduced speed to check the water level measured.

Fire Dampers

3.11 The following conditions must be verified and carefully tested:

a. The operation of all fire dampers; if they are of the thermal reset type, they shall be tested using a heat-generating object.

b. The reset path of the fire damper meets the reset requirements.

c. The status (open/closed) of the fire damper shall be labeled.

d. If the fire damper is installed on a duct, its position shall be marked at a conspicuous location on the duct.

4 Commissioning

Air Handling and Supply Air Systems

4.1 Fan drives, direction of rotation, speed and current shall be adjusted to the requirements of the manufacturer's instructions.

4.2 After the installation has been tested and it is ensured that good and safe conditions for start-up have been achieved, the unit shall be started up and adjusted so that it meets the design requirements. The proportional balancing method described in CIBSE Commissioning Code "A" must be followed. The air volume must be within the tolerances specified in the design summary.

4.3 When the system in which supply air and return air are interconnected has been balanced, and the pressure in the supplied space is higher than or equal to atmospheric pressure, the exhaust fan shall first be shut off to balance the supply air system, then the supply fan shall be turned on, and the exhaust air system shall then be balanced.

4.4 When the systems are interconnected and the pressure in the supplied space is lower than atmospheric pressure, the supply fan shall first be shut off to balance the exhaust air system, then the exhaust fan shall be turned on, and the supply air system shall then be balanced.

4.5 After the duct balancing work is completed, the air volume in each supply and exhaust duct shall be measured. The air volumes delivered by all supply grilles and diffusers shall be measured and recorded.

4.6 The volume control dampers on the main supply duct and the exhaust ducts must be fixed, and their positions shall be marked.

4.7 The volume control dampers of all supply grilles and diffusers must be locked to prevent changes in air volume.

Room Air Supply

4.8 The pressure relief valves and pressure stabilizers must enable the room to reach the set indoor static pressure and maintain it constant. Grille directional vanes and diffuser cones must be installed to ensure that the airflow achieves the specified flow pattern. Visualization techniques may be used to demonstrate that the required airflow pattern can be achieved.

Air Conditioning

4.9 Air velocities or pressure drops must be set for all heater batteries, cooling coils and humidifiers. After setting by the methods specified in CIBSE Commissioning Codes "W" and "R", the relevant regulating devices shall be locked to prevent alteration.

Control Systems

4.10 Commissioning of the control systems may only be carried out after the air supply systems and the air conditioning equipment have been fully commissioned.

4.11 Because of the special nature of control systems, and since each manufacturer's system has its own unique components and devices, commissioning shall be carried out by the supplier, with a representative of the user present to supervise.

4.12 Inspect the locations of all control and monitoring sensors and verify their accuracy.

4.13 The components of the control system must be tested to determine that they function properly.

4.14 If the unit is provided, in addition to a control panel in the plant room, with a remote "user" panel, the operation of both shall be tested; this applies particularly to the commissioning of operating theatre and laboratory systems.

5 Performance Testing

Air Flow

General Ventilation Systems

5.1 The performance of the system must be measured and compared with the information provided by the designer/manufacturer

Operating Room - Ultra-Clean System

5.2 The method for measuring air velocity at the ultra-clean terminal is to first divide the surface into a number of approximately 300mm×300mm small squares, as shown in Figure 1, and then measure the air velocity at the center of each small square at a height of 2m above the floor; the results should fall within the range specified in Table 1. In the central area of 1.8m×1.8m, the air velocity measured at the center of each small square at a height of 1m above the floor should be at least 0.2m/s.

1 2 3 4 5 6 7 8 9 10
A + + + + + + + + + +
B + + + + + + + + + +
C + + × × × × × × + +
D + + × × × × × × + +
E + + × × × × × × + +
F + + × × × × × × + +
G + + × × × × × × + +
H + + × × × × × × + +
I + + + + + + + + + +
J + + + + + + + + + +
  • +: Air velocity measured at 2m above the floor (see Table 1)
  • ×: Air velocity measured at 2m above the floor (see Table 1), (and air velocity measured at 1m above the floor)
  • ●: Bacterial sampling point

Figure 1 Ultra-Clean System — Test Grid

5.3 In the test grid measurement method, a unidirectional hot-wire anemometer is used to take one precise measurement every 10s, and the average air velocity of each small square is calculated.

5.4 Some ultra-clean systems are designed so that the supply air velocity can be variable within the supply air area, with the velocity gradually decreasing from the center toward the surrounding edges. In such systems, the supply air volume is equal to the total of a single-velocity system of the same area; the air velocity of each small square is also measured according to the above method, and the flow rate value of the supply air is determined.

Table 1 Minimum Supply Air Velocity

Vertical air supply system (air velocity measured at 2m above the floor) Vertical air supply system (air velocity measured at 2m above the floor) Horizontal air supply system
Fully enclosed canopy no more than 1m above the floor Fixed partially enclosed canopy 2m above the floor 1m from the surface of the filter or diffuser (these wall panels may also be detachable additions to the fixed partially enclosed canopy)
0.3m/s Average of 0.38m/s 0.40m/s

Laboratory Systems

5.5 The performance measurement of this system requires the use of the specified safety cabinet or fume cupboard operating procedures (see Section 5.17)

Local Exhaust Ventilation (LEV)

5.6 On-site exhaust systems can protect staff from harm caused by chemical substances, hazardous gases, biological agents and dust. They work by capturing contamination at source and discharging it. The following are typical examples of local exhaust ventilation applications: laboratory fume cupboards; medical safety cabinets, including those for the extraction of cytotoxic agents and radiopharmaceutical cabinets; pathology and biological safety cabinets, formalin liquid and specimen preparation trays; mobile glutaraldehyde cabinets and workstations; dental grinders, vibrators, casting machines, sand blasters and electroplating baths; X-ray and photographic processing machines; extraction systems at post-mortem saws, autopsy tables and specimen tables; EBME instrument washers; extraction hoods for fixed and mobile welding benches; extraction at charging benches; chemical analysis benches; spray brushes; sawdust extraction systems for woodworking machines; and general dust extraction systems.

5.7 Where local exhaust ventilation is provided as a system, thorough examination and testing shall be carried out to the standards required by the "Maintenance, examination and testing of local exhaust ventilation systems" published by the Health and Safety Executive. Testing and examination must be carried out by a competent person, and records kept for future reference.

5.8 The face velocity and canopy velocity of the cabinets, and the static pressure beneath the canopy extract hood, should be measured and recorded. The actual performance of the system should at least meet the requirements specified in the standards.

5.9 Certain local exhaust ventilation systems, such as safety cabinets and fume cupboards, must comply with the provisions of the relevant guidance documents.

Biological Safety Cabinets

5.10 Safety cabinets must pass the examination and testing carried out in accordance with BS 5726 Part 1. This is highly specialised work and should be carried out by the manufacturer.

Unit Capacity and Controls

5.13 When verifying that the air-conditioning units meet the design requirements, both the air-conditioning manufacturer and the controls specialist should be present at the same time to jointly commission the system.

5.14 The units must demonstrate the ability to achieve the set indoor design conditions under the winter and summer design parameters specified in the design; artificial loads need to be created to simulate internal heat gains or losses and the indoor design conditions.

5.15 After completion of the unit performance tests, thermohygrometers should be placed in each room or work area served by the unit and on the frost coil at the upstream end of the supply air ductwork. The unit should run for 24 hours with all doors closed, during which all indoor parameters should be maintained within the set ranges.

5.16 For ultra-clean systems in operating theatres, where a full enclosure with partial walls fitted with extension panels is provided, airflow control devices may be fitted so that when the removable extension panels are in place, the supply air velocity of the system is reduced. This variable-speed performance must be verified, and a statement concerning this function should be noted on the control panel.

5.17 The commissioning and testing of safety cabinets and fume cupboards is highly specialised work and should be carried out by the equipment manufacturer or a competent specialist. Any special performance requirements and the particular mode of operation of the ventilation system serving the work area should be specified; the associated run timers, differential pressure gauges and unit interlocks should all be verified.

Noise

5.18 For commissioning noise level measurements, a sound level meter should be placed in the empty room. After measuring the external noise and the noise generated by the supply air system, a base noise level is obtained. When the room is in use, this noise level constitutes a continuous background noise, and the difference between the two should reach 10 decibels or more. The design noise level of the ventilation unit refers to the noise level without taking into account the noise generated by other units; these noises constitute the allowable value of the ambient noise.

5.19 The noise level refers to the noise level at maximum air velocity when the designed system is in operation. Commissioning noise measurements should be carried out with the unit and all other equipment operating normally, and with the design-specified parameters of airflow, humidity and temperature maintained.

5.20 An industrial sound level meter of Type 2 to BS 3489 or IEC 651 may be used to test the noise level.

5.21 The noise level should be the reading taken at the standard positions for normal listening measurement, taken asymmetrically at positions at least 1 m from any surface and 1.5 m above floor level. Unless otherwise specified, the measured results should not exceed 55 dB(A).

5.22 Where certain terms and conditions of the contract are inadequate, use should be made of a sound level meter complying with the Type 1 requirements of BS 4197 or IEC 651... ...the required precision sound level meter. The noise levels shall be read at five different positions in the room: 1.5m from each corner of the room and at the centre of the room, and shall not be taken on any line of symmetry. The test noise level shall be calculated using the logarithmic average of the five different values.

5.23　Discrete frequency components and noise sources may be determined using the procedure specified in HN(76)1267. When the components and other equipment have been installed and the average sound pressure level near the occupied area has been measured, a discrete frequency component may be deemed to exist if the sound pressure level in a 1/3 octave band, within 50–12500Hz in the area near the dwelling, exceeds the arithmetic mean of the two adjacent 1/3 octave bands listed in Table 2.

Table 2　Frequency range

1/3 octave band centre frequency/Hz 63–100 125 160 200–250 315–10 000
Difference not exceeding/dB 6 5 4 3 2

For this test, sound measuring instruments of high accuracy complying with the Class 1 requirements of BS4197 or IEC651 shall be fitted with a filter device complying with IEC R225.

Table 3　Indoor noise levels — operating theatres

Room Noise level/dB(A) Ventilation plant commissioning measurement/dB(A) Ventilation plant design/dB(A)
Ultra-clean operating theatre Remote plant: 50 Combined plant: 55
Conventional operating theatre 50 45 40
Anaesthetic room 50 45 40
Preparation room 50 45 40
Scrub room 50 45 40
Corridor 55 50 45

Safety Cabinets

5.24　The noise level shall be read at 0.3m from the air outlet and 1m from any other component, including ductwork; the value shall not exceed 55dB(A).

Filter Requirements

Filters for General Ventilation

5.25　In on-site performance testing, it is generally not required to test first- and second-stage filters and their housings.

HEPA Filters (for exhaust-protected enclosures and laboratory extract air)

5.26　Pathogenic agents can be dispersed into the room through damaged or improperly installed HEPA terminal filters. Whether the filters have been correctly and completely installed must be tested using the method given in Appendix C of Part 1 of BSS295, namely the "filter installation leak test method". Particles produced by a dispersed oil particulate (DOP) generator are injected into the return air duct and the upstream section of the terminal filter, and a photometer is then used to scan the filter face and its housing to determine whether leakage is present.

5.27　If at any point the photometer repeatedly and continuously indicates results exceeding 0.01% of the upstream reading, it can be confirmed that a leak has occurred.

If a filter fails this test, the filter should be replaced. If the filter housing fails the test, it should be repaired and then retested.

Ultra-Clean Ventilation (UCV) System

5.28 After the terminal filter has passed the installation test, testing should begin to determine whether particles generated outside the clean zone can be induced into the clean zone.

5.29 The performance of a partial-wall system may be affected by the ingress of room air into the clean zone of the ultra-clean ventilation system. Air containing particles should be deliberately introduced outside the partial wall to check whether it penetrates into the aseptic zone. This test should be carried out both when no operation is in progress and when the surgical equipment is in place.

5.30 Set up a DOP generator to generate particles outside the ultra-clean ventilation system. This particle generation test is the last task to be performed in testing the system. Record the number of particles downstream of the terminal filter, ensure that the generated particles are not recirculated back by the system, and then remove the detection instruments. It is recommended that particles be generated outside the four faces at the upper part of the partial wall of the ultra-clean ventilation system and that the particle concentration be measured at the lower part; the degree of particle dispersion should be measured at 1m above the floor at the small squares indicated in Table 1.

5.31 The particle counter should measure the dust concentration at the surface of the filter as a base concentration. Taking this base concentration as the reference, the central area is effectively zero; this reference concentration should be 1% lower than the peripheral 1.8m zone and 10% lower than other areas outside the clean zone.

Bacterial Sampling

Conventional Air Supply Systems

5.32 Unless otherwise specified, bacterial sampling is generally not carried out for conventional air supply systems or local exhaust systems.

Operating Theatres

5.33 To test the concentration of airborne bacteria in the supply air, all doors should be closed and the operating theatre left unoccupied while the air supply system runs for 1h; the bacterial sampler on the operating table should then be switched on to take samples. The culture results of the sampled air on non-selective media should not exceed 35 bacteria or fungi/m³.

5.34 Analyse the test results to determine the approximate types of microorganisms present. A high proportion of fungi may be the result of improper filter installation.

5.35 Testing of the airborne bacterial concentration during an operation should be carried out as soon as possible after handover is complete. Unless the number of staff in the operating theatre exceeds the normal range or the workload is excessively heavy, the average number of airborne bacteria or fungi (CFU) measured at 5s intervals should not exceed 180 per m³. This work should be carried out by the designated infection control officer or the bacteriologist (consultant) (if they are not the same person).

Ultra-Clean Ventilation Systems

5.36 During surgical operations, testing should be carried out between the scalpel and the wound. This test should meet the following minimum requirements:

  • a. The bacterial content in the supply air of the diffuser or terminal filter diffuser should be ＜0.5CFU/m³. If a leakage test has already been carried out on the air filter after installation, this test may be omitted.
  • b. During the operation, for air samples collected near the wound, when personnel are wearing ordinary cotton clothing, the average bacterial content of the air within 300mm of the surgical wound should be ＜10CFU/m³; when isolation clothing is worn or a clothing exhaust system is used, the value should be ＜10 CFU/m³.
  • d. During the operation, in air samples collected at the periphery of the clean zone, the concentration should not exceed 2010CFU/m³ when ordinary cotton surgical clothing is worn, and should be below 110 CFU/m³ when isolation clothing is worn or a clothing exhaust system is used.
  • e. Microbiological safety cabinet.

5.37 Testing should be carried out using the method specified in BS5726 "Biological safety cabinets", Part 1, Appendix D, "Determination of the protection factor of Class I and Class II cabinets"; the check should be completed after installation.