Identifying precise leak site locations and size using the Portascanner® 520
Before installing Clean Agent fire suppression systems (used when sprinklers are inappropriate due to damaging enclosure contents) there are regulatory tests which much be undertaken in order to ensure the safety of the building structure and effectiveness of fire suppression. Currently, a Room Integrity Fan Test, using fans to pressurise and depressurise the protected room, is the most commonly used, and universally accepted method of testing room integrity in preparation for use of a Clean Agent (which could be an inert gas or hydrocarbon). This test determines the Peak Pressure and Hold Time necessary for ensuring the effectiveness of these fire suppression systems.
This article shall focus on the last stage of regulatory testing, namely the locating of potential leak sites in the case of a room having an insufficient Hold Time. It aims to reveal the crucial, previously undiscovered industry benefits of using the Portascanner™ Airtight Integrity Test Indicator for leak detection.
The testing of room integrity is necessary for adherence to standards and requirements outlined by the NFPA 2001: Standard on Clean Agent Fire Extinguishing Systems and ISO 14520: Gaseous Fire-Extinguishing Systems, established concerning enclosure design and testing. The success of clean agent fire suppression systems relies on holding the agent in the room for the correct amount of time, allowing for optimum agent concentration necessary to extinguish the fire. This is part of the total flooding principle on which inert gases and halocarbon agents function. Room integrity tests are imperative for the determination of both the Hold-Time and the Peak Pressure needed for successful fire suppression. The level of leakage is carefully monitored in order to ensure the correct agent concentration is achieved; room integrity must be ‘tight’ enough to ensure sufficient retention time according to NFPA or ISO, yet remain ‘loose’ enough to prevent enclosure damage at discharge.1 The presence of undesired and unregulated leak sites reduces room integrity and will hence dramatically impact the Hold Time and Peak Pressure, placing room contents and potentially wall structures at risk.
Both NFPA 2001 and ISO 14520 standards recommend using Door Fan Testing to analyse the enclosure and retrieve the necessary values for Hold Time and Peak Pressure, and to measure the leakage of a room. This test uses large fans to pressurise the room in question by blowing air into it. The fan speed is adjusted to obtain flow pressure equivalent to the pressure exerted during a fire suppression system discharge, before reversing the fan to depressurise the room. Airflow and pressure readings are then entered into a computer software programme which calculates the Equivalent Leakage Area (ELA) and subsequently the Hold Time and Peak Pressures. This method, created by Retrotec’s Door Fan testing kit, is a reputable and effective method of room integrity testing, and has been the most respected method in recent years. However, a thesis by Todd Hetrick exposed the Door Fan integrity test as applicable for determining the total area of all leakages, but incapable of revealing the specific locations of leak sites.2 Furthermore, the Fan Test Room Integrity Testing kit itself is not only unable to provide specific leak locations, but also does not provide any information concerning leak aperture. Given that most gaseous chemical agents used for fire suppression are heavier than air, the agent will begin to leak out of any lower level penetrations left unsealed, making their identification ever more important. In the case of too little leakage, vents must be created to reduce Peak Pressure in the event of agent discharge for fire suppression. In the case of too much leakage, unwanted leak sites need to be identified and sealed.