(2) Heat release rates may be calculated from the reading of the thermopile output voltage at any instant of time as:
HRR = Heat release Rate kw/m2 Vm = measured thermopile voltage (mv) Vb = "Blank" thermopile voltage Kh = Calibration Factor (Kw/mv) Vb is the "blank" test obtained by a run conducted with an empty sample holder assembly.
Refer to paragraph (7) above.
(3) The integral of the heat release rate is the total heat release as a function of time and is calculated by multiplying the rate by the data sampling frequency in minutes and summing the time from zero to two minutes.
(g) Criteria. The total positive heat release over the first two minutes of exposure for each of the three or more samples tested must be averaged, and the peak heat release rate for each of the samples must be averaged. The average total heat release must not exceed 65 kilowattminutes per square meter, and the average peak heat release rate must not exceed 65 kilowatts per square meter.
(h) Report. The test report must include the following for each specimen tested:
(1) Description of the specimen.
(2) Radiant heat flux to the specimen, expressed in W/cm2.
(3) Data giving release rates of heat (in kW/m2) as a function of time, either graphically or tabulated at intervals no greater than 10 seconds. The calibration factor (kh) must be recorded.
(4) If melting, sagging, delaminating, or other behavior that affects the exposed surface area or the mode of burning occurs, these behaviors must be reported, together with the time at which such behaviors were observed.
(5) The peak heat release and the 2-minute integrated heat release rate must be reported.
HRR V V m Km b h= − ×( ).02323 2
Smoke Monitor - Chimney •0.25m →
• Baffle
0.31m → 0.368m Radiation Shield Reflector
• 0.33m "Globars"
0.79m Ra Mechanical Devise to Maintain Sample Pilot Position Flame
• 0.41m Sample Holder Air Distributor Plates -
- 0.41m
0.20m → Air Inlet [Figure 1. Release Rate Apparatus] 707
24g Chromel Alumel Glass insulated Duplex T.G. Wire + Weld or Silver Solder Bend Wire Bock Against Metal Surface → 10 → 3.2 (5/32 in.) Drill - 0.55 (22mll) Stainless Steel (Unless denoted otherwise, all dimensions are in mitimeters) Figure 2. Compensator Tab 708
5/18/2009 АС 25-17А 10 -
- Exhaust Stack Figure 3. Compensator Tab Mount 1K Д Thermopile R, 5K Q To Recorder Compensator T.C.
Figure 4. Wiring Diagram 709
EMF → Time - Time B Figure 5. Square Wave Response 710
Top 115 150 . Mask 156 (Unless denoted otherwise, all dimensions are in millimeters.)
Figure 6A. "Globar" Radiant Panel 711
TOP T -25- 115 • Reflector, adjust slope, top and bottom, for uniform heat flux on sample.
- Mask
- 1/4" - 20 Machine Screw 75 g (Unless denoted otherwise al dimensions are in millmeters.)
[Figure 6B. "Globar" Radiant Panel] 712
SPRING 2 Radlus Flange, 1" Long 3/8" 156
ANGLE IRON
RETAINER FRAME 165 24 ga Steel
SAMPLE HOLDER Washer 50mm OD 13mm ID Weld lasher 50mm OD 13mm ID all dimensions are in millimeters.) (Unless denoted otherwise, Screw Drill & 1/2 - 13 nut Weld 1/2" Nut \ Tap for 10-32 Machine Screw to Washer 2 Radlus, 5 Flange 165
MOUNTING BRACKET Figure 7 713
- 125mm → 25
- 25 — No. 32 Drill Hole
- 9.5 O.D.
9.5 Tubing Leak-Free Seal on 6.35 Pilot Tubing (Unless denoted otherwise, all dimensions are in millimeters.)
FIGURE 8 714
715 1180. APPENDIX F, AMENDMENT 25-66, Effective September 26, 1988. This amendment revised Part IV and added Part V.
PART IV - TEST METHOD TO DETERMINE THE HEAT RELEASE RATE FROM CABIN MATERIALS EXPOSED TO RADIANT HEAT.
Appendix F-Part IV-Test Method to Determine the Heat Release 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 flow of air passes. The specimen's exposure is determined by a radiant heat source adjusted to produce the desired total heat flux 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 piloted ignition. The combustion products leaving the chamber are monitored in order to calculate the release rate of heat.
(b) Apparatus. The Ohio State University (OSU) rate of heat release apparatus as described below, is used. This is a modified version of the rate of heat release apparatus standardized by the American Society of Testing and Materials (ASTM), ASTM E-906.
(1) This apparatus is shown in Figures 1A. All exterior surfaces of the apparatus, except the holding chamber, must be insulated with 25 mm thick, low density, high temperature, fiberglass board insulation. A gasketed door through which the sample injection rod slides forms an airtight closure on the specimen hold chamber.
(2) Thermopile. [The temperature difference between the air entering the environmental chamber and that leaving is monitored by a thermopile having five hot and five cold, 24 gauge Chromel-Alumel junctions. The hot junctions are spaced across the top of the exhaust stack, 10mm below the tope of the chimney. 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 (Figure 5). The cold junctions are located in the pan below the lower air distribution plate (Refer to paragraph (b)(4)). Thermopile hot junctions must be 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, glass insulated, duplex thermocouple wire is welded or silver soldered to the tab as shown in Figure 2, and the wire bent back so that it is flush 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 (approximately 4.5mm O.D., 9mm O.D.)
washers between 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-
716 K ohm variable resistor (R1) of the thermopile bleeder shown in Figure 4. When adjusting compensation, keep R1 as small as possible. Adjustment of the compensator must be made during calibration (Refer to paragraph (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 insufficient 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) Subtract the output of the compensator from the thermopile. The junctions enclosed in the dotted circle of Figure 4 are kept at the same constant temperature by electrically insulating the junctions and placing them on the pipe carrying air to the manifold, then covering them and the pipe with thermal insulation.
(v) Thermopile hot junctions must be cleared of soot deposits on a daily basis during periods of testing.
(3) Radiation Source. [A radiant heat source for generating a flux up to 100 kW/m2, using four silicone carbide elements, Type LL, 20-inches (50.8 cm) long by 5/8-inch (1.54 cm) O.D., nominal resistance 1.4 ohms, is shown in Figures 2A and 2B. The silicone carbide elements are mounted in the stainless steel panel box by inserting them through 15.9mm holes in 0.8mm thick ceramic fiber board. Location of the holes in the pads and stainless steel cover plates are shown in Figure 2B. The diamond shaped mask of 24-gauge stainless steel is added to provide uniform heat flux over the area occupied by the 150 by 150mm vertical sample.]
(4) Air Distribution System. The air entering the environmental chamber is distributed by a 6.3 mm thick aluminum plate having eight, No. 4 drill-holes, 51 mm from sides on 102 mm centers, mounted at the base of the environmental chamber. A second plate of 18 gauge steel having 120, evenly spaced, No. 28 drill holes is mounted 150 mm above the aluminum plate. A wellregulated air supply is required. The air supply manifold at the base of the pyramidal section has 48, evenly spaced, No. 26 drill holes located 10 mm from the inner edge of the manifold so that 0.03 m3/second of air flows between the pyramidal sections and 0.01 m3/second flows through the environmental chamber when total air flow to apparatus is controlled at 0.04 m3/second.
(5) Exhaust Stack. An exhaust stack, 133mm by 70mm in cross section, and 254mm long, fabricated from 28 gauge stainless steel, is mounted on the outlet of the pyramidal section. A 25mm by 76mm plate of 31 gauge stainless steel is centered inside the stack, perpendicular to the air flow, 75mm above the base of the stack.
[(6) Specimen Holders. The 150 mm x 150 mm specimen is tested in a vertical orientation. The holder (Figure 3) is provided with a specimen holder frame, which touches the specimen (which is wrapped with aluminum foil as required by paragraph (d)(3) of this part) along only the 6 mm perimeter, and a "V" shaped spring to hold the assembly together. A detachable 12 mm X 12 mm X 150 mm drip pan and two .020-inch stainless steel wires (as shown in Figure 3) should be
717 used for testing of materials prone to melting and dripping. The positioning of the spring and frame may be changed to accommodate different specimen thicknesses by inserting the retaining rod in different holes on the specimen holder.
Since the radiation shield described in ASTM E-906 is not used, a guide pin is added to the injection mechanism. This fits into a slotted metal plate on the injection mechanism outside of the holding chamber and can be used to provide accurate positioning of the specimen face after injection. The front surface of the specimen shall be 100mm from the closed radiation doors after injection.
The specimen holder clips onto the mounted bracket (Figure 3). The mounting bracket is attached to the injection rod by three screws which pass through a wide area washer welded onto a 1/2-inch nut. The end of the injection rod is threaded to screw into the nut, and a .020- inch thick wide area washer is held between two 1/2-inch nuts which are adjusted to tightly cover the hole in the radiation doors through which the injection rod or calibration calorimeter pass.
(7) Calorimeter. A total-flux flush calorimeter must be mounted in the center of a 1/2-inch Kaowool "M" board inserted in the sample holder to measure the total heat flux. The calorimeter must have a view angle of 180 degrees and be calibrated for incident flux. The calorimeter calibration must be acceptable to the Administrator.
(8) Pilot-Flame Positions. Pilot ignition of the specimen must be accomplished by simultaneously exposing the specimen to a lower pilot burner and an upper pilot burner, as described in paragraph (b)(8)(i) and (b)(8)(ii), respectively. The pilot burner must remain lighted for the entire 5-minute duration of the test.
(i) Lower Pilot Burner. The pilot-flame tubing must be 6.3mm O.D., 0.8mm wall, stainless steel tubing. A mixture of 120 cm3/min. of methane and 850 cm3/min. of air must be fed to the lower pilot flame 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. The pilot burner must be a straight length of 6.3mm 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 the tubing, 60mm apart, for gas ports, all radiating in the same direction. The first 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 and positioned by an adjustable "Z" shaped support mounted outside the environmental chamber, above the viewing window. The tube is positioned 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 flame lengths of 25mm.