The major cause of failure of gas fire suppression systems — such as Inergen®, SAPPHIRE™, IG-541, IG-55 or FM200 is inadequate room sealing. Room Integrity Testing guarantees your fire protection strategy and provides peace of mind. Researcher has found that rooms get leakier with time, usually due to changes in construction, cabling, or services.
It is therefore important to ensure that good room integrity is established and maintained, particularly bearing in mind the potential consequences of system failure. Gas suppression systems are a logical solution for rooms containing IT or electronic equipment, however if the room leaks the fire suppression agent will escape before the fire is effectively controlled. That is why Australian Standard AS1851-2005 “Maintenance of fire protection systems and equipment” requires an Enclosure Integrity Test each year. The benefits of this are widely recognised by insurers and regulatory authorities, who frequently require testing.
Torvac technicians are accredited operators of Retrotec Room Integrity Testing equipment. Torvac is committed to using state-of-the-art testing equipment to assure you will receive the most accurate information available. Our testing procedure will grant you the confidence to know that your system is capable of responding to a fire emergency. Testing of your gaseous protected rooms can be arranged conveniently to minimise any disruption to your business.
The door fan itself merely measures the enclosure leakage area and the pressures that may exist across it. The computer software in conjunction with the DG-700 Hand Held digital pressure I flow gauge does the rest of the simulation and comes up with the prediction. The Retrotec CA2001 software walks the user through all the steps in a controlled way to ensure each step is done in accordance with the applicable NFPA or AS ISO 15420 standards.
The Minneapolis Fan Test Unit is temporarily installed in a doorway leading from the protected space to a large open area or outdoors. The fan speed is adjusted to obtain a pressure between the test room and the volume surrounding the test room. This pressure (usually 1 0 to 15 Pa or 0.04” to 0.06” W.C.) is similar to the steady state pressure (column pressure) exerted by the gaseous extinguishing agent at floor level at the start of a typical 1 0-minute retention period. The pressure created by the Minneapolis Fan Test Unit causes air to move through leaks at a detectable rate. This makes it very easy to pinpoint exactly where leakage occurs using a chemical smoke.
The door fan pressurizes the enclosure to the same pressure exerted by the agent on the floor after discharge. The flow needed to create this pressure is used to calculate the leakage area of the enclosure. By measuring the airflow rate and the pressure created, the computer software calculates the Equivalent Leakage Area (ELA), or the total area of all the cracks, gaps, and holes in the test room. The flow pressure across the blower inlet is converted into flow by the computer software. The door fan pressurizes the enclosure to the same pressure exerted by the agent on the floor after discharge.
The flow needed to create this pressure is used to calculate the leakage area of the enclosure.
The measurement is done by first blowing air out of the room (depressurisation) and then into the room (pressurisation).
The gaseous extinguishing agent mixes violently upon discharge, resulting in a homogeneous mixture. Pressures created in the first few seconds of discharge (referred to as dynamic discharge pressure) are ignored in the retention time prediction model because they are so short and because large factors for loss are already allowed for in the concentration formula.
The heavier-than-air agent pressing down upon the floor creates a small positive pressure. Flow develops whenever a hole has a pressure difference across it. The greater the pressure and the larger the hole, the greater the agent lost. A small negative pressure will develop at the top of the room that allows a similar volume of air to flow back into the room from leaks at the higher elevations.
If air-moving equipment in the room is shut off at discharge, the agent mixture will tend to stay separate from the air infiltrating through the upper leaks. The intersection between the pool of agent mixture and clean air above is referred to as the agent/air interface. This is called the descending interface case. This interface drops, as the agent is lost out of the room through leaks in the floor and lower wall area. Air from outside the room generally replaces agent by infiltrating through leaks in the upper half of the room. If air-moving equipment is left on during the retention period, the infiltrating air will become mixed in with the agent. This is called the continual mixing case. The concentration at the floor will decay at the same rate as the concentration near the ceiling. In some cases, air flow into or out of the room is created by other causes (e.g., damper or duct leakage). This airflow produces a static pressure, which pushes the agent out faster. This static pressure is therefore usually eliminated. The door fan test measures total leakage areas and static pressures. Below ceiling leaks can then be measured separately using a flex duct or plastic on the ceiling to neutralise ceiling leaks. All other variables such as room volume and heights are easily measured on site. The model predicts how many minutes it will take for the descending interface to reach the minimum protected height specified by the Authority Having Jurisdiction or, for the concentration to fall to the minimum percent acceptable for the continual mixing case.
The logic for the Room Integrity Testing and survey is to provide assurance to property managers/owners that an appropriate level of protection and a high level of reliability exist for each hazard area.
While this report sets out some recommendations for improving the level of fire protection, it is also important to note that the fire protection systems and equipment need to be properly managed and maintained to ensure their performance and reliability.