DOOR FAN TEST 2018-08-01T12:57:07+00:00

Door Fan Test

THE DOOR FAN TEST

WHAT is Door Fan Test

Used for several years in the United States for the design of heating and air conditioning systems at the end of the 1980s, it has been developed and codified in the field of fire engineering, for the inspection of premises protected with extinguishing systems saturation of gas. The Door Fan Test test protocol was officially formalized in the 1989 edition of the standard: NFPA 12A: “Halon 1301 Fire Extinguishing Systems“.

The DOOR FAN TEST is a procedure for analyzing and verifying the properties of a room, that is to say, of its ability to prevent the presence of a pressure gradient between the interior and the outside creating an airflow through the walls creating different. The Door Fan Test provides a method for assessing the magnitude of local leakage and its ability to retain gas within a Total Flooding Discharge System. It also allows for systematic research and detection of the leak areas on the surfaces that delimit the locale.

It is put into operation by pressurizing and depressurizing the room and by measuring the air flow rates necessary for the purpose by means of an apparatus comprising: A panel to be adapted to open a room door compartment to be examined by 1 or 2 fans with adjustable speed, install on the above panel to enter and extract air from the room. A control console with instruments for measuring indoor and outdoor pressures on the premises, generated air flow to obtain them, indoor and outdoor temperatures. A calculation unit (PC) for the processing of measured values and extrapolation of the local sealing characteristics Figure 1. Door Fan Test Equipment

EXECUTION DOOR FAN TEST

The execution of the Door Fan Test before the project predisposition, therefore allows verification of the feasibility of a gas-saturation protection system within the volume to be protected, while also allowing to assess the technical and economic convenience of alternative solutions. It also provides at the design information necessary for the determination of any factors Project or maintenance discharges, also in relation to the dangers associated with the presence of people in the protected rooms. In the following, we will describe what are the aspects that most affect the protected volume of sealing characteristics, making from time to time refer to local real cases object of Door Fan Test.

THE STAGES OF THE TESTING

The DFT is conceptually develops in 3 stages:
MEASURE: It measures the injected / extracted air flow entities in / from the local to generate inside a given value for the overpressure / depression.
CALCULATION: From the measured values we can calculate the equivalent leakage area (ELA: Equivalent Leakage Area), ie the total area of all leaks, cracks, joints and porous surfaces that allow leakage from the local subdivision surfaces in question.
PREDICTION: Knowing the value of Equivalent Leakage Area you can perform a valuation of the gas retention time in the room.

THE TEST PROCEDURE
Let’s now look at the Door Fan Test procedure in detail to understand what principles it is based on.
Measurement and Calculation
The procedure followed in the execution of a Test involves entering a stream of air into the room to Pressurize it to the overpressure value that would be determined by a real discharge of extinguishing agent inside it. The measurement of the input air flow gives an indication of the leakage (ie of the flow of air coming out). Indeed, under equilibrium conditions, it results in the unit of time: incoming air volume = outgoing air volume.
Knowing, therefore, the air flow rate, the fan discharge coefficient in the presence of a laminar air flow, induced overpressure and air density can accurately calculate the ELA as the theoretical area of a hole from the outlines, through which passes all the leakage flow, to the test pressure. The same type of test will be repeated by performing a Depressurization of the room in order to minimize the influence on Static Pressure measurement, ie a pressure delta between the interior and exterior of the room already present before the test begins. of ELA will be given by the mean between the two values obtained as described above
SEALING OF LOSSES

Full repetition of the test
In carrying out the tests described, the leak is searched through the use of chemical smoke.
The use of the smoke generates a modest introduction into the environment during the pressurization phase
amount of smoke, by means of special “smoke puffers” (a sort of smoke emitter), in close proximity
cracks and probable leaks, to appreciate smoking outbreaks, which allows you to detect
even hidden losses (small cracks in the walls, leaks along the window frames or along the windows
couplings between perimeter panels, etc …).

DOOR FAN TEST Execution
The execution of the DFT before the project predisposition, therefore allows verification of the feasibility of a gas-saturation protection system within the volume to be protected, while also allowing to assess the technical and economic convenience of alternative solutions. It also provides at the design information necessary for the determination of any factors Project or maintenance discharges, also in relation to the dangers associated with the presence of people in the protected rooms. In the following, we will describe what are the aspects that most affect the protected volume of sealing characteristics, making from time to time refer to local real cases object of Door Fan Test.
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