Integrity Testing Of Enclosures

Integrity Testing Of Enclosures
Enclosures protected by gaseous fire suppression systems should tested for air-tightness upon commissioning of the system and annually thereafter. This is critical to ensure that the system will work effectively when activated; too much air-leakage will result in the concentration of the fire suppressant agent falling too quickly.

Air Pressure Testing provides the necessary Room Integrity Testing to the required NFPA 2001 or ISO http://aptsoundtesting.co.uk/fireenclosuretesting.html methodologies.

We have extensive experience in testing all types and sizes of enclosure, from server rooms in offices to hospital intensive care units. In each case we carry out the necessary volumetric calculations prior to the test and use calibrated test fan systems along with laptops running complaint CA2001 software to determine results immediately upon completion of the enclosure integrity test.

In the event of a failed enclosure integrity test we will locate and record the air leakage sites using smoke-puffers – if permitted. We subsequently provide full fire enclosure reports, incorporating all necessary data test information and certification, usually within a few days of the enclosure integrity test. This will ensure that you have all of the required information to undertake accurate remedial works on the enclosure.

Remedial Works to Protected Enclosures

The majority of enclosure integrity test failures are caused by the lack of enclosure integrity, and/or the ability of the enclosure to adequately retain the extinguishant. The correct initial design concentration can sometimes be achieved but the enclosure is not able to retain the extinguishant agent for the required holding period. Once the enclosure has failed the integrity test, remedial work should then be undertaken to reduce the leakage from the protected enclosure. This may include;

  • Sealing all cracks or penetrations leading into or out of the protected enclosure.
  • Sealing all pipe chases and cable trays to be sealed around the outside and inside where they penetrate the perimeter boundaries of the protected enclosure
  • Walls to be caulked around the inside perimeter at both high and low level
  • Sealing of porous block walls – this can be remedied by painting etc.
  • The addition of door sweeps or drop seals, weather stripping around jambs
  • Sealing of windows/glazed sections to the area
  • The sealing of the underside of doorways within the floor void.

The best way of locating air leakage paths is to undertake a smoke test whilst a test kit is in place and the protected enclosure is pressurized, the air leakage paths can then be sealed and a 2nd integrity test undertaken. Once the appropriate remedial work has been undertaken then the enclosure should be retested to confirm if an acceptable level of integrity has been reached.

We have extensive experience in testing all types and sizes of enclosure, from server rooms in offices to hospital intensive care units. In each case we carry out the necessary volumetric calculations prior to the test and use calibrated test fan systems along with laptops running Clean Agent software to determine results immediately upon completion of test.

In the event of a failed enclosure integrity test result, we will locate and record the air leakage sites using smoke-puffers if permitted. We subsequently provide full reports, incorporating all necessary data test information and certification, usually within a few days of the test. This will ensure that you have all of the required information to undertake accurate remedial works.

What Rooms Usually Require Enclosure Integrity Testing

Computer and plant rooms require gaseous fire extinguishing systems protection. Given the consequences of fire damage and down time for such critical equipment, it is essential that an integrity test is undertake before handover of the enclosure and annually thereafter, or if the protected rooms enclosure has received new penetrations.  For a fire suppression system to work, the room must have sufficient integrity to retain an extinguishing concentration for a specified period after discharge. Failure to do so may cause the fire to reignite causing further damage. As this is the predominant cause of failure, the British and International Standard (BS: ISO14520) requires that an enclosure integrity test (aka room integrity test, fan test, or pressure test) be conducted on system installation and thereafter at annual intervals.

Air Pressure Testing have undertaken hundreds of enclosure integrity tests on varying room types from comm’s room/s to massive power station turbines enclosures; and have the experience to help you achieve a test pass at the first attempt. We are one of a very few companies that fully understand the theory behind extended discharge tests and are able to undertake testing to enclosures where extended discharge tests are required.

Extended discharge tests are commonly used where it is not possible to fully seal an enclosure – such as a Gas Turbine Enclosure in a power station. An initial discharge is release in a sufficient concentration that extinguishes the fire, and then an extended discharge takes place to replenish the extinguishing agent at a suitable rate to prevent the fire reigniting for a required period of time.

Initially the enclosure integrity test was introduced as an environmentally friendly alternative to discharge testing following the phase out of halon extinguishant under the Montreal Protocol on ozone depletion. It is applicable to all sizes of enclosure and all extinguishing gases, including Argonite, Inergen, Proinert, IG55, FM200, FE25, HFC 227ea, FE25, Novec 1230 and CO2.

We ensure that our enclosure integrity testing is clean and non-disruptive, using a door mounted fan(s) to measure leakage flow. Work may continue as normal in the room during the test. An immediate result is obtained for the total room leakage and consequent extinguishant retention time. If this is below that required by the Standard, a detailed inspection is carried out to identify all major leakages for remedial sealing. A formal report is issued detailing the results and any recommendations. The failure report should be retained for regulatory authority/ insurer’s reference. If you fail the test – Air Pressure Testing can undertake the remedial works for you; and due to the importance of these areas; specialise in out of hour’s remedial works as we understand the impact/cost of closing down areas such as turbine rooms etc. to minimise disruption.

Descending Interface Explained

The criterion used to determine whether the amount of leakage is acceptable is the retention time. In most circumstances, extinguishant is lost via leakage through low level apertures to be replaced by fresh air entering at high level, thus creating a descending interface. The retention time is the time it takes for the interface to reach the highest item requiring protection – a  minimum retention time of ten minutes applies in most cases. The only way to determine the retention time are either to discharge the gas and measure concentration or, universally preferred, to undertake an enclosure integrity test or fan enclosure test. This utilises a door-mounted fan to pressurise the room and the air flow is measured. From this an equivalent leakage area is derived and the retention time predicted.

Protected Enclosure Construction

In many cases in-situ fire foam is widely used as it is frequently seen to be a simple sealing method to fill gaps. There is however a couple of problems associated with it. Firstly, it has a tendency not to adhere to all the surfaces so that what might superficially seem to be a good seal has, when examined closely, a significant leakage path running around it. Secondly, care should be taken to ensure that its use does not breach any fire resistance requirement.

Constructional joints are another feature that requires sealing. This may include board joints and the junctions between wall and floor elements. Any profiles in ceilings/walls should be sealed at the junction with adjacent walls/ceilings. Even small open profiles will pose a leakage problem if there are many of them.

Enclosure door sets should incorporate flexible ‘smoke’ seals and frames should be backfilled or mastic sealed. Rolling shutters and louvered doors are a particular problem and should, if possible be avoided. If drop curtains are used to reduce leakage through these items it is important that they run in channel guides to reduce edge leakage and unwanted displacement.

Air supply and extract ducting will usually require the dampers are closed on extinguishant discharge. There will inevitably be some leakage past louvered dampers. Whilst this will not normally pose a problem, it will become significant in enclosures where there are extensive areas of dampers in relation to the enclosure size. Under these circumstances it should be ensured that the dampers are well adjusted to minimise leakage.

Thought should also be given to other penetrating elements. Cable ducts may be well sealed externally but are likely to provide a leakage path unless packed internally at the point of penetration – this is usually one of the main reasons for protected enclosure test failures.

Finally, it should be remembered that, despite the need for good practice, some leakage is not only inevitable but necessary to help relieve initial overpressure – enclosures do not need to be completely air tight.

It is hoped that the above comments are of assistance to those responsible for sealing protected rooms. Clearly successful sealing can only be determined by fan enclosure testing. However, provided the above points are carefully and fully applied there is no reason why the enclosure should not satisfy the retention time requirement. If you think you have a problem in terms of your enclosure construction – please contact us at info@airpressuretesting.net as we can send across our air sealing checklist to help you prepare for the enclosure test. We can also offer a sealing service should it be required.