Such testing is required for new build to (a) certificate the room / system, and (b) to certify that indeed the design concentration is reached in the first instance as excessive leakage may be so great as to lose the design concentration during the release period itself. Testing is required each year to re-certify the room and the gas suppression performance, and may be a requirement of the Clients Insurance Company to revalidate the protection provided to the space.
The application of a gas suppression system requires that the room space (including the total envelope floor void / ceiling void) are adequately sealed to contain the weight of gas within the space for the required period of time against an allowable leakage rate. The means to test the room for ‘ tightness ‘ is by the Retrotec Room Integrity Door Fan Pressure Test means. A calibrated and certified axial flow fan is latched into rigid expandable panels that fill the opened door frame space.
By running the calibrated fan at a certain speed thus generating pressure into / from the space, and by monitoring the pressure differential within and external to the room, that flow rate is actually measured, data inputted to software together with the protected height and the weight of gas ( FM200 / FE25 / Novec 1230 or Proinert / Argonite / Inergen Inert Gas, yes inert gas is basically air, but it still has weight ! ) and a descending interface height hold time, or mixing concentration result is obtained.
If the room is tight enough, then a pass is achieved. If the room is too leaky, then a fail is recorded and the room requires further sealing and a retest until a pass is achieved.
UK Air Testingcarry out such Room Integrity testing and can offer a remedial sealing and retesting service.
For any gaseous fire suppression installation to be effective, the design concentration must first be achieved, and then maintained at suitable levels within the risk. In order to achieve thistheprotected area must be adequately sealed around its boundary. Integrity Testing calculates the leak-tightness of a room and predicts how long it takes for the interface between the extinguishing agent and the air to descend to a given level. The test equipment comprises of variable speed fans, expandable door panels, pressure gauges and a dedicated portable computer.
The door fan unit is fitted into a doorway of the protected area by means of the expandable door panels designed to fit most door frame sizes, and measures the size of holes in the enclosure and the pressures that may exit across them.
The fan speed is adjusted to obtain a steady pressure between the test area and the volume surrounding the test (equivalent to the column weight exerted by the extinguishing agent following a discharge). This pressure is then maintained whilst readings are taken from pressure gauges.
The measured rate of air input needed to maintain this pressure level is equivalent to the amount leaking from the test area. A second measurement is taken by doing the first test in reverse i.e. by depressuring the test area. The two readings are averaged to reduce error.
The computer then converts the flow and pressure readings into an Equivalent Leakage Area, or the total area of all the cracks, gaps and holes in the test area. The data generated is then processed using specifically designed computer software, in compliance with the National Fire Protection Association (NFPA) and the British Standard ISO 14520 which predicts the period of time that the concentration will be held in the test area at any given height. This retention time can be further calculated for different heights.
The computer software has also been designed to be conservative with its predictions. The software produces the worst case scenario in which 50% of the cracks, gaps in the test area are at a low level where heavier gas/air mixture will seep out and 50% are at a high level where lighter air will enter to displace it. This approach makes the results extremely reliable and means that any system which passes the room integrity test would have been virtually certain to pass a full discharge test.
Within an hour of the completed tests the computer produces a printout with full details of the input and test results, with a detailed report following in the post shortly afterwards. Failure is indicated if it takes less than ten minutes for the agent/air interface to drop below the minimum specified protected height.