The purpose of this procedure is to define the step by step method to implement the correct practices for the performance of Integrity Test for the proper functioning of fire suppression system through the the guidelines contained herein so as to ensure that the job execution complies with the project requirements and serves the intended function to satisfactory level.
Preparatory Works Inspection
- Determine the boundary of the protected enclosure.
- Identify areas that have been temporarily sealed or where sealing is incomplete.
- Locate & inspect all openable doors, hatches, movable partitions that form a part of boundary of enclosure.
- Locate, identify & determine the control systems for all air handling plant & associated dampers.
- Locate the clean agent cylinders & check the type & weight.
- Identify the doorways or other openings within the enclosure that need to be opened for the duration of the test.
- Determine a suitable door way in which the door fan unit will be located.
- Check the availability of suitable power outlets adjacent to this doorway (12amps at 120 volts & 6 amps at 240 volts is the maximum needed per door fan blower).
In order to predict the retention time of a protected enclosure a number of parameters are required. Such as:
– The extinguishing agent and the weight of the agent used in the system
– The volume of the protected enclosure
– The maximum height of the protected enclosure from the lower slab to upper extent of the intentional agent discharge
– The height of interest, which is the height within the protected enclosure at which the design concentration must be maintained (75% is often used as a default or where the contents of the room are unknown)
– The value and cause of any static bias pressure (existing pressure differential) which would exist in the enclosure at the time of a discharge.
– The leakage area of the enclosure.
Derivation of Parameters
These parameters are determined in various ways:
- The type of gaseous clean agent and its weight is taken from the fill weights detailed on the cylinders.
- The volume of the protected enclosure is measured on site by the integrity testing engineer (to minimize the possibility of error it is advisable that this is cross checked with a calculated volume from another source).
- The maximum height of the protected enclosure is measured on site.
- The height of interest is usually measured. on site, generally after the particular equipment requiring protection has been specified (usually 75%).
- The minimum retention time required is generally specified by the client (usually 10 minutes).
- Any static bias pressure in the enclosure is measured with a pressure gauge and smoke to verify direction as part of the integrity test.
- The leakage area of the enclosure is directly derived from measurements made with a door fan during the integrity test.
Preparing for the test of a particular enclosure comprises:
- Agreeing the timetable for the test with the appropriate supervisory personnel and advising them of the requirements of the test.
- Transporting the necessary equipment to the doorway in which the door fan unit will be located for the test
- Removing any papers or other objects that are likely to be affected by the air movements resulting from the use of the door fan
- Wedging open doorways between areas adjacent to the envelope of the enclosure under test to allow sufficient return airflow between the door fan and the leakage sites in the enclosure. “DO NOT CLOSE” signs to be posted at such doorways. .
- Ensure that the set up of the protected enclosure- simulates that which would occur after a dicharge,i.e. HVAC shut down, dampers closed etc.
- Ensuring that all doorways and openings into the enclosure, other than the doorway in which the fan unit will be set up, are shut and that “DO NOT OPEN” signs are fixed to them.
- Wedging open doorways between any sub-divisions of the protected enclosure. “DO NOT CLOSE” signs to be posted at such doorways.
- When there is a raised floor in the protected enclosure, free movement of air between the room and the floor void is required for the integrity test If there are insufficient grilles and/or other openings in the false floor, tiles comprising approximately one percent of the floor area must be removed to ensure that this takes place.
- When there is a suspended ceiling in the protected enclosure, and the ceiling void is protected by the extinguishing system, free movement of air between the room and the ceiling void is required for the integrity test. If there are insufficient grilles and/or other openings in the suspended ceiling, tiles comprising approximately one percent of the floor area of the enclosure must be removed to ensure that this takes place.
Door Fan Installation
- Having selected a suitable doorway for use during the test the adjustable door panels are fitted in the doorway and suitable pieces of plastic or cardboard are used to seal any gaps. One or two fan units are then fitted into the adjustable panels.
- Pressure gauges are leveled (for analog gauges),zeroed, and then connected to the fan apparatus. The tubing for the external tap for the room pressure gauge is Connected to the outside of one of the adjustable panels and the end of it is fixed 10 to 12 feet away from the outlet side of the door fan unit, and away from all significant air flows (e.g. from HVAC systems).
- Having set up and zeroed the equipment, the enclosure under test is depressurized to approximately 15 Pascal. This is undertaken with the protected enclosure set up to simulate that which would occur after a discharge, i.e. HVAC shut down, dampers shut etc.
- All dampers are then inspected using chemical smoke to check that they are closing properly. The walls, floor and roof of the enclosure are also inspected for significant leaks, and the cause of any major air currents noted identified. Finally. doors and hatches are also inspected to ensure that they are closing properly.
- Depending upon the characteristics of the enclosure anq the nature and size of the installed air handling plant some parts of the leakage check may be undertaken with the air conditioning still operating if temperature build-up in the enclosure is a particular problem.
- Without activating the equipment, and with all openings into the enclosure under test shut, any bias pressure in the enclosure is measured. If all HVAC systems are shut off, this should be zero.
- If a significant bias pressure exists, its cause must be investigated and, if possible, remedied. Incorrect or inadequate allowance for the effects of bias pressures can give rise to very significant errors in the leakage area measurement and hence the predicted retention time.
Room and Flow Pressure
- The door fan unit is then activated and run up to achieve a room pressure approximating that which would be created during an actual discharge of the extinguishing system. The room pressure required is calculated from the initial concentration of agent and the maximum height of the protected enclosure. If it is not possible to achieve this pressure difference because the enclosure ~is excessively leaky, a pressure difference of a least 10 Pascals should be created before readings are taken.
- The room pressure measurement and the flow pressure measurement (for each fan unit used) is then measured and recorded. The gauges should be inspected and should remain stable for at least 30 seconds prior to the operator taking measurements. If the gauges do not remain steady the cause should be investigated. In general, most variations or fluctuations in the pressure measurements will be caused by the wind. Damping equipment can be used to minimize the effect of the wind upon the measurements, however it is important to effectively seal all external surfaces in an enclosure where pressure variations caused by the wind have been noted.
Inspection during Test
- If the measured leakage area yields predicted retention times that are too short to be acceptable, a detailed inspection for leakage sites may be undertaken while the protected envelope is depressurized. Such an inspection -must always be undertaken when the pre~test inspection has been omitted. If this is included the procedure is as detailed below.
- With the-fan unit(s) operating, an inspection of the enclosure is made. This includes:
- Assessing the size and relative importance of any holes or openings that are observed remembering that low level leaks are much more significant than high level leaks.
- Tracking down the sources of any major air currents that are noted.
- Examining the walls, floor and ceiling of the enclosure for major leaks, particularly at any locations where services penetrate the envelope of the enclosure.
- Inspecting doors, hatches and other openings to ensure that they will close correctly.
- Checking that the dampers are working ( if possible).
- Having achieved satisfactory readings of room pressure and flow pressure and performed an inspection of the enclosure under test, the equipment is de-activated and removed from the doorway(s) in use. All signs and wedges must also be recovered.