(i) Lower Pilot Burner.Thepilot-.ametubing mustbe6.3mmO.D.,0.8mm wall, stainless steel tubing. A mixture of 120 cm3/min. of methane and 850cm3/min. of air must be fed to the lower pilot .ame burner. The normal position of the end of the pilot burner tubing is 10 mm from and perpendicular to the exposed vertical surface of the specimen. The centerline at the outlet of the burner tubing must intersect the vertical centerline of the sample at a point 5mm above the lower exposed edge of the specimen.]
(ii) Upper Pilot Burner.Thepilot burner must be a straightlength of6.3mm O.D., 0.8mm wall, stainless steel tubing is 360mm long. One end of the tubing shall be closed, and three No. 40 drill holes shall be drilled into thetubing,60mmapart,forgasports,all radiatinginthe samedirection. The .rst hole must be 5mm from the closed end of the tubing. The tube is inserted into the environmental chamber through a 6.6mm hole drilled 10mm above the upper edge of the window frame. The tube is supported andpositionedby anadjustable ”Z”shaped support mounted outsidethe environmental chamber, abovethe viewing window.Thetubeispositioned above and 20mm behind the exposed upper edge of the specimen. The middle hole must be in the vertical plane perpendicular to the exposed surface of the specimen which passes through its vertical centerline and must be pointed toward the radiation source. The gas supplied to the burner must be methane adjusted to produce .ame lengths of 25mm.
(c) Calibration of Equipment.
(1) Heat Release Rate.[A burner as shown in Figure 4 must be placed over the end of the lower pilot .ame tubing using a gas tight connection. The .ow of gas to the pilot .ame must be at least 99 percent methane and must be accurately metered.Priorto usage,the wettest meterisproperlyleveled and .lled with distilled water to the tip of the internal pointer while no gas is .owing. Ambient temperature and pressure of the water are based on the internal wet test meter temperature. A baseline .ow rate of approximately 1 liter/min is set and increased to higher preset .ows of 4, 6, 8, 6, and 4 liters/min. The rate is determined by using a stopwatch to time a complete revolution of the wet test meter for both the baseline and higher .ow, with the .ow returned to baseline before changing to the next higher .ow. The thermopile baseline voltage is measured. The gas .ow to the burner must be increased to the higher preset .ow and allowed to burn for 2.0 minutes, and the thermopile voltage must be measured. The sequence is repeated until all .ve values have been determined. The average of the .ve values must be used asthe calibrationfactor.Theprocedure mustbe repeatedifthepercent relative standard deviation is greater than 5 percent. Calculations are shown in paragraph(f).]
(2) Flux Uniformity. Uniformity of .ux over the specimen must be checked per-iodically and after each heating element change to determine if it is within acceptable limits of plus or minus 5 percent.
(d)
Sample Preparation.
(1)
[The standard size for vertically mounted specimens is 150 X 150 mm with thickness up to 45 mm.]
(2)
Conditioning. Specimens must be conditioned as described in Part 1 of this Appendix.
(3)
Mounting. Only one surface of a specimen will be exposed during a test. A single layer of 0.025mm aluminum foil is wrapped tightly on all exposed sides.
(e)
Procedure.
(1)
The power supply to the radiant panel is set to produce a radiant .ux of 3.5W/cm2.The .uxismeasured atthepoint which thecenterof thespecimen surfacewill occupy whenpositionedfortest.Theradiant .uxismeasured after theair .owthrough theequipmentisadjusted tothedesired rate.Thesample should be tested in its end use thickness.
(2)
The pilot .ames are lighted and their position, as described in paragraph (b)(8), is checked.
(3)
The air .ow to the equipment is set at 0.04 plus or minus 0.001m3/s at at-mosphericpressure.Properair .owmay besetand monitoredby either:(1) An ori.cemeterdesigned toproduceapressuredrop of atleast200mmof the manometric .uid,orby(2) arotometer(variableori.cemeter) with ascale capable of being read to plus or minus 0.0004m3/s. The stop on the vertical specimen holder rodis adjusted so that the exposed surface of the specimen is positioned 100mm from the entrance when injected into environmental cham-ber.
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本文链接地址：FAA规章 美国联邦航空规章 Federal Aviation Regulations 4(56)
