ture and the chamber temperature. If these temperatures are in agreement to within ±5 °C with those determined in accordance with 9.9 above, the chamber

is ready for use.

11.2 Mount the specimen tray on the sliding platform and position with stud bolts (see Figure 9).

11.3 Ignite the pilot burner, move the specimen into the chamber, and close the door. Start the timer. After 2 minutes preheat, with the pilot burner on and set so that the flame is horizontal and 5 cm above the specimen, bring the pilot burner into contact with the center of the specimen at the 0 cm mark. Leave the pilot burned flame in contact with the specimen for 5 minutes, then remove to a position 5 cm above the specimen and leave burning until the test is terminated. 11.4 If the specimen does not ignite within 5 minutes following pilot burner flame application, the test is terminated by extinguishing the pilot burner flame. For specimens that do ignite, the test is continued until the flame goes out. Observe and record significant phenomena, such as discoloration, charring, smoldering, etc.

11.5. When the test is completed, the door is opened, the specimen platform is pulled out.

11.6 Measure the distance burnd, i.e., the point of farthest advance of the flame front, to the nearest 0.1 cm. From the flux profile curve, convert the distance to watts/cm2 critical radiant heat flux at flame out. Read to two significant figures. A suggested data log format is shown in Figure 10.

11.7 Remove the specimen tray from the moveable platform.

11.8 The succeeding test can begin as soon as the panel apparent black body temperature and chamber are verified (see 11.1). The specimen tray should be at room temperature prior to insertion of the next specimen.

12. REPORT

12.1 The report shall include the following:

12.1.1 Description of the attic floor insulation.

12.1.2 Description of the procedure used to prepare the floor insulation specimen.

12.1.3 Number of specimens tested, including critical radiant flux and density for each specimen as tested.

12.1.4 Observations of the burning characteristics of the specimen, such as discoloration, charring, smoldering, etc.

APPENDIX A-PROCEDURE FOR CALIBRATION OF RADIATION INSTRUMENTATION

A1. RADIATION PYROMETER

A1.1 Calibrate the radiation pyrometer by means of a conventional black body enclosure placed within a furnace and maintained at uniform temperatures of 490, 500, and 510 °C (914, 932, 950 °F). The black body enclosure may consist of a closed chrometal metal cylinder with a small sight hole in one end. Sight the radiation pyrometer upon the opposite end of the cylinder where a thermocouple indicates the black body temperature. Place the thermocouple within a drilled hole and in good thermal contact with the black body. When the black body enclosure has reached the appropriate temperature equilibrium, read the output of the radiation pyrometer. Repeat for each temperature.

A2. TOTAL HEAT FLUX METER.

A2.1 The total flux meter shall be calibrated by the National Bureau of Standards,' or alternatively, its calibration shall be developed by transfer calibration methods with an NBS calibrated flux meter. This latter calibration shall make use of the radiant panel tester as the heat source. Measurements shall be made at each of the nine dummy specimen positions and the mean value of these results shall constitute the final calibration.

A2.2 It is recommended that each laboratory maintain a dedicated calibrated reference flux meter against which one or more working flux meters can be compared as needed. The working flux meters should be calibrated according to the procedure of A2.1 at least once per year.

1 Direct requests for such calibration services to the: Optical Radiation Section, 232.04, National Bureau of Standards, Washington, D.C. 20243.