When a suppression system is designed for a room, it’s designed to reach a certain concentration and then hold that concentration for a specific amount of time. It’s ability to hold this concentration is crucial for its ability to put out a fire.

Most rooms, especially server rooms and electrical rooms, have a lot of wiring, conduit, HVAC ducts, and other components coming into the room. All of these penetrations of the walls act as potential areas where the gas can leak out and cause the room to not adequately hold the concentration for as long as it needs to so that it ensures the fire is extinguished.

The door fan test, also called room integrity fan test, is used is to predict the enclosure’s retention time should the buildings clean agent suppression system be discharged.

How to conduct a door fan test

“The last thing we do when we commission a new system is a door fan test,” explains Adam W. Fire Alarm Service Manager at Fire Systems, Inc.

Through a combination of measuring the size of holes and pressure in an enclosure and computer software simulations, a prediction of how long an agent would stay in a room can be generated.

To measure total room leakage, a door fan is temporarily installed in a doorway leading from a test room to a larger open area. The fan speed is adjusted to obtain a pressure between the test room and the volume surrounding the test room. The measurement is done by blowing air out of the room and then into the room. These two readings are then averaged.

The computer then converts flow and pressure readings into an Equivalent Leakage Area (ELA), or the total area of all the cracks, gaps, and holes in the test room.

Adam explains the process: “The door fan test involves the use of a big unit that seals the door with a large fan and basically a fancy pressure gauge. You run the fan at different speeds, for negative pressure and positive pressure, and record the pressure readings. Once you enter these readings into the software for the unit, it tells you how long that room will hold the concentration for.”

Door fan vs. discharge test

Before 1989, the door fan test did not exist. NFPA now recognizes this test as a reliable test for all clean agent systems. NFPA 2001 and NFPA 12A address this test. The discharge test was a procedure that tested only 5 sides of a room, leaving the ceiling as an unprotected/unchecked area where smoke or fire could easily enter.

To get rooms to pass the discharge test, installers would use a fan mounted in a doorway as a means to locate hidden leaks using chemical smoke. After the leaks were identified and sealed, the room would receive a pass on the discharge test. This procedure has since become known as the “door fan” test.

The problem with the discharge test is that it only ensures agent distribution in one location. There was also no requirement to repeat this test.

The door fan test, in contrast, must be repeated on a regular basis or whenever extra holes are made in the room.

Importance of a door fan test

 NFPA 2001 requires that a minimum concentration of 85 percent of the adjusted minimum design concentration be held at the highest level of combustibles for a minimum of 10 minutes. A door fan test assures the room can hold the clean agent for this required period of time.

The reason why this retention is so important is to ensure the proper performance of any total flooding clean agent fire suppression system. If the agent can’t get to the full perimeter of a room, you’re left with unprotected areas or space where the fire could spread. This is especially important for protecting mission critical data like computer server rooms.

Scheduling your door fan test

 It’s also important to have this test performed at least once every five years or when any remodel or changes are done to the protected area.

If a room fails this door test, someone must go around using fire caulk to seal up any holes.

A licensed fire protection professional should conduct your door fan test. Fire Systems, Inc. can perform your door fan test as well as install, inspect, and repair any component of your buildings fire protection systems. We’re highly trained, highly certified, and have decades of experience in the fire protection industry. Call us today at 770-333-7979 or visit our website for more information.