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The purpose of a door fan test is to determine how long the fire suppressing chemical or agent that is being released into a room will stay in the room if it were ever discharged and to locate any unknown leaks. The test is environmentally friendly and does not involve the discharging of the system. It 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
The room is sealed in advance and a door fan is temporarily installed in a doorway leading from the protected space to another room or area. A computer with software designed for this test will measure size of the holes or cracks in the room and calculate what pressure is being exerted. The computer basically maps out where the leaks are and gives the technician the information needed so that the room can be sealed properly to keep the chemical in the room for the amount of time required to be code compliant with the NFPA (National Fire Protection Association). In some cases damper or duct leakage can cause a static pressure in the room or enclosure. This pressure can push the fire suppressing agent out faster so it must be taken into account in the calculations. The equipment for this test is specialized to pressurize and depressurize the room to get accurate readings and the technician has to have a required level of certification to operate the equipment and understand the information provided by the computer program.
The local AHJ (Authority Having Jurisdiction for fire inspections) determines whether or not a door fan test is to be done after a clean agent system is installed. If a room is remodeled or has additional holes created after the test, then another test may be required per the AHJ.
After discharge from nozzle located at ceiling height, the agent which is heavier-than-air will press down upon the floor and create a small positive pressure. Flow develops whenever holes have pressure across them. The greater the pressure and the larger the hole, the greater the agent lost. As the agent runs out the bottom, a small negative pressure develops at the top. This pulls air in through the higher level leaks. If the room’s air-moving equipment is off during the retention period, the agent will drain out-much like water out of a hole in a bucket. Air will then flow in through the upper leaks. Air from outside the room replaces the lost agent by infiltrating through leaks in the upper half of the room, but if the bottom of the room is well sealed then this retards the process. The goal is to make this occur slowly enough so that the room retains enough concentration of the agent for the required retention time to assure no fire re-ignition and to allow emergency action by trained personnel.
No, the HVAC industry and other types of contractors, have used smoke pencils and smoke guns for many years to see air flow and look for leaks. The local AHJ determines what test type they will allow in their jurisdiction. We inquire of them when we are requesting permitting information to let you know in advance what type of testing will be required. Our goal is to help locate all leaks and assist you in getting the correct room integrity to assure your system performs as it was designed to. We are happy to include cost information for any testing required by the local authority. |
