(4)
Panel orientation(ceiling or sidewall.)
] Amdt. 25-60, E.. 6/16/86 ′
Elodie Roux. Septembre 2003
Appendix F
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Elodie Roux. Septembre 2003
Appendix F
FAR 25.F4 : Appendix F–Part IV–Test Method to Determine the Heat Re-lease Rate From Cabin Materials Exposed to Radiant Heat
(a)
Summary of Method.
(1) The specimen to be tested is injected into an environmental chamber through which a constant .ow of air passes. The specimen’s exposure is determined by a radiant heat source adjusted to produce the desired total heat .ux on the specimen of 3.5 W/cm2, using a calibrated calorimeter. The specimen is tested so that the exposed surface is vertical. Combustion is initiated by pilotedignition.The combustionproductsleavingthe chamberaremonitored in order to calculate the release rate of heat.
(b)
Apparatus.TheOhioStateUniversity(OSU) rate ofheat release apparatus asdes-cribedbelow,is used.Thisis a modi.ed version ofthe rate ofheat release apparatus standardizedby theAmericanSociety ofTesting andMaterials(ASTM),ASTM E-906.
(1)
This apparatus is shown in Figures 1A. All exterior surfaces of the apparatus, except the holding chamber, mustbe insulated with 25 mm thick,lowdensity, high temperature, .berglassboardinsulation.Agasketeddoorthrough which the sample injection rod slides forms an airtight closure on the specimen hold chamber.
(2)
Thermopile.[The temperature di.erence between the air entering the environ-mental chamber and that leaving is monitored by a thermopile having .ve hotand .vecold,24gaugeChromel-Alumeljunctions.Thehotjunctionsare spaced across the top of the exhaust stack, 10mm below the tope of the chim-ney. One thermocouple is located in the geometric center, with the other four located 30mm from the center along the diagonal toward each of the corners (Figure5).The coldjunctions arelocatedin thepanbelow thelower airdistri-butionplate(seeparagraph(b)(4)).Thermopilehotjunctions mustbe cleared of soot deposits as needed to maintain the calibrated sensitivity.]
(i)
Thermal Inertia Compensator. A compensator tab is made from 0.55mm stainless steel sheet, 10 by 20mm. An 800 length of 24 gauge Chromel-Alumel,glassinsulated,duplexthermocouple wireis welded or silver sol-dered to the tab as shown in Figure 2, and the wire bent back so that it is .ush against the metal surface.
(ii)
The compensator tab must be mounted on the exhaust stack as shown in Figure 3 using a 6-32 round head machine screw, 23mm long. Add small(approximately4.5mm O.D., 9mm O.D.) washersbetween the head of the machine screw and the compensator tab to give the best response to a square wave input. (One or two washers should be adequate.) The ”sharpness” of the square wave can be increased by changing the ratio of the output from the thermopile and compensator thermocouple which is fed to the recorder. The ratio is changed by adjusting the 1-K ohm variable resistor(R1)of the thermopile bleeder shown in Figure 4. When adjusting compensation, keep R1 as small aspossible.Adjustment of the compensator mustbe madeduring calibration(seeparagraph(c)(1)) at a heat release rate of 7.0 plus or minus 0.5 kW.
(iii) Adjust the washers and the variable resistor (R1) so that 90 percent of full scale response is obtained in 8 to 10 seconds. There must be no overshoot, as shown in Figure 5A. If an insu.cient number of washers is added, or R1 is too small, the output with square wave input will look like Figure 5B; if too many washers are added and R1 is too large, the output will look like Figure 5A.
(iv)
Subtractthe output of the compensatorfromthethermopile.Thejunc-tions enclosedin thedotted circle ofFigure4 arekept at the same constant temperatureby electrically insulating thejunctions andplacing them on the pipe carrying air to the manifold, then covering them and the pipe with thermal insulation.
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