Standard Test Methods for Measurement of Flammability of Materials in Cleanrooms Using a Fire Propagation Apparatus (FPA)
|Publication Date:||1 January 2017|
This standard shall determine and quantify the flammability characteristics of materials containing polymers that are used in cleanroom applications.
The propensity of these materials to support fire propagation, as well as other flammability characteristics, are quantified by means of a fire propagation apparatus.
Measurements obtained include time to ignition (tign), chemical (Qchem) , and convective (Qc) heat release rates, mass loss rates (m) , and smoke extinction coefficient (D).
This standard includes the following separate test methods:
(1) The ignition test, which shall be used for the determination of tign
(2) The combustion test, which shall be used for the determination of Qchem , Qc , m , and D
(3) The fire propagation test, which shall be used for the determination of Qchem from burning of a vertical specimen
The test methods described herein evaluate the suitability of materials and products containing polymers for use in cleanrooms.
These test methods also provide the transient response of such materials and products to prescribed heat fluxes in specified inert or oxidizing environments, for use in mathematical modeling.
The fire propagation apparatus is also designed to obtain laboratory measurements of generation rates of fire products (CO2, CO, and, if desired, gaseous hydrocarbons).
Distinguishing features of the fire propagation apparatus include the following:
(1) Tungsten-quartz external (isolated) heaters to provide a radiant flux of up to 65 kW/m2 to the test specimen, this flux remaining constant whether the surface regresses or expands
(2) Provision for combustion or upward fire propagation in prescribed flows of normal or either oxygen-enriched or oxygen-vitiated air
(3) The capability of measuring heat release rates and exhaust product flows generated during self-sustained, upward fire propagation on a vertical test specimen 0.305 m high
(4) The capability for characterization of the smoke yield from a specimen
The test methods are part of a quantitative methodology for assessing the propensity of materials and products used in cleanrooms to support upward fire propagation and to generate effluent, such as smoke.
This methodology consists of the correlation of flammability indices resulting from the test methods with corresponding characteristics measured during real-scale fire propagation experiments.
Indices resulting from the test methods include critical heat flux (CHF), thermal response parameter (TRP), fire propagation index (FPI), effective heat of combustion (EHC), and smoke yield (ys ) and smoke damage index (SI).
The TRP and CHF indices are obtained from the ignition test, the EHC and ys indices are obtained from the combustion test, and the FPI is derived from a fire propagation test in air containing 40 percent oxygen.
This standard is composed of three separate test methods that shall be used in conjunction with a fire propagation apparatus as follows:
(1) The ignition and combustion test methods shall involve the use of horizontal specimens, in normal air, subjected to a controlled external radiant heat flux that shall be set from 0 up to 65 kW/m2.
(2) The ignition test method shall be conducted under ambient conditions, whereas the combustion and fire propagation test methods shall be conducted with a prescribed airflow within a quartz pipe.
(3) The fire propagation test method shall involve the use of vertical specimens, in air having a 40 percent (by volume) oxygen concentration, subjected to ignition near the base of the specimen from an external radiant heat flux of 50 kW/m2 and a pilot flame.
The ignition test method shall be used to determine the TRP and CHF of horizontal specimens.
The TRP shall be determined from changes in the time required for sustained ignition by a pilot flame as a function of the magnitude of a constant, externally applied radiant heat flux.
The CHF shall be determined from the magnitude of externally applied radiant heat flux below which there is no sustained ignition.
Measurements also shall be made of the time to initial fuel vaporization.
The surface of the specimens shall be coated with a thin layer of black paint.
The combustion test method shall be used to determine the EHC and ys , as well as the chemical and convective heat release rates when the horizontal test specimen is exposed to an external radiant heat flux of 50 kW/m2 in the apparatus.
The fire propagation test method shall be used to determine the FPI of vertical specimens. A 40 percent oxygen concentration in the inflow shall be used to simulate the radiant heat flux from real-scale flames.
The fire propagation test of vertical specimens shall not be used for materials that melt and form a liquid pool while burning.
This standard does not purport to address all safety problems associated with its use. It shall be the responsibility of the user of this standard to establish appropriate safety and health practices.