1、MILITARY STANDARD CALORIMETRY FOR THERML BATTERY HEAT SOURCES TEST AND CALIBRATI ON PROCEDURES Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-1454 MI 77777L1 008775b T I IdSb Test method and procedure for calor MI L-STD-1454 5 July 1971 DEPA
2、RTMENT OF DEFENSE ngton, D.C. 20310 metry MIL-STD-1454 I 1 a This military standard was developed by the Department of Defense. 2. This military standard is mandatory for use by all Departments and Agencies of the Department of Defense. 3. kcomended corrections, addi tions, or deletions should be ad
3、dressed to Harry Diamond Laboratories (AMXDO) , Washington, .C. .20438. ii Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MI L-STD-1454 5 July 1971 Paragraph 1. 1.1 2. 3. 3.1 3.1.1 3.-1 .2 3.1.3 4. 5. 5.1 5.2 5.3 5.3.1 5.3.2 5.3.3 5.3.4 5.3.5 5.3.6
4、5.4 5.4.1 5.4.2 5.4.3 5.4.4 5.4.5 5.5 5.5.1 5.5.2 5.5.3 5.5.4 5.5.5 5.6 Figures 1. ,. z. 3. 4. Appendix A. CONTENTS Page FI GURES 1 1 1 1 1 1 1 1 1 2 2 2 3 3 3 3 3 3 3 3 3 4 4 5 5 6 6 6 6 7 7 8 9 10 11 12 APPENDIX Notes for Using Data Sheet 13 A a iii Provided by IHSNot for ResaleNo reproduction or
5、networking permitted without license from IHS-,-,-MIL-STD-1454 MI 77777LL 0087758 3 I MI L-STD-1454 5 July 1971 1. SCOPE 1.1 Purpose. This standard prescribes a method for testing thermal battery heat source powder samples for calorific values. calibrating the calorimeter. Since thermal batteries mu
6、st operate over a wide operating temperature range, the heating value expressed as calories per gram of the material must be closely controlled. The methods contained herein specify sui table conditions obtainable in the laboratory which give results equivalent to actual use. They also assure the re
7、quired reliability of the equipment, and provide for reproducibility of test results National Bureau of Standards (NBS) certified standard reference material wi 11 be used for this purpose. It includes the method for The following standard samples are available: SRM-1651 - Powder with Nominal Value
8、of 350 Calories/gram SRM-1652 - Powder with Nominal Value of 390 Calories/gram SRM-1653 - Powder with Nominal Value of 425 Calories/gram. Other standard samples wi 11 be provi ded as requi red. 2. REFERENCED WCUMENTS 2.1 The following document of the issue in effect on date of invitation for bids or
9、 request for proposal form a part of this standard to the extent speci- fied herein. SPEC1 FI CAT IONS ASTM #116C-68 - Specification for ASTM Sol id-stem Thermometers 3. DEFINITIONS 3.1 Definitions. For the purpose of this standard, the following definitions apply: 3.1.1 Calorific value. Calorific v
10、alue in this procedure is defined as calories per gram. A gram-calorie is the heat required to raise one gram of water from 14.5“C to-15.5“C. 3.1.2 Certified standard reference material. .Certified standard refer- ence material is a powder, certified ti, have specific calorific value for use as a st
11、andard in testing powder samples from the production of thermal batteries. It is also used in calibrating the calorimeter. 3.1.3 Qualified test facility. A qualified test facility is a facility capable of calibrating the instrument for test and certi,fying by means of a certification report that the
12、 calibrated da?a is correct. - 4. GENERAL STATEMENT (Mot applicable) Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-3454 MI W 9999913 0089759 5 I MIL-STD-1454 5 July 1971 5 , DETAI L REQUI REKNTS reacting to produce the desired heat. The mat
13、erial is a zirconium-barium chromate mixture which can be ignited readily by flame, spark, friction, or discharge of static electricity, This mixture burns rapidly generating intense heat and sol id ash. Both the heat from the reaction and the hot slag which may be thrown from the reaction zone can
14、cause severe burns. However, if proper precautions are taken, this heat powder is no more dangerous than solvents such as acetone and ether. The fol lowing instructions , therefore, are recommended for safe-handling of these materials: area , lation of static charges; personnel should wear grounded
15、wrist straps and avoid wearing silk or synthetic fabrics that can generate static electricity. Cotton clothing is preferred, a container or exposed at one time.should be limited to 50 grams. able to break 50 gram samples down to smaller quantities for laboratory use. d. The heat powder should be kep
16、t in covered conductive rubber, containers or small metal containers with rubber stoppers, Friction lids should not be used. Desiccators should be made of metal, contain only solid desiccants, and should be placed on a grounded surface before cover is removed to insert or remove a sample. it should
17、be transferred with a grounded metal scoop. face shield while handling heat powder. a. No flame, smoking, or matches should be permitted in the heat powder b, Working surfaces Should be conductive and grounded to prevent accumu- c, The area should be kept clean and the amount of heat powder stored i
18、n It is advis- I e, Since heat powder may generate an electrostatic charge when poured, f. Personnel should wear leather gloves and either safety glasses or a I I millimeter (m) pr open the exhaust valve slowly and close. The bomb has now been flushed once. e, Repeat step d. an additional five times
19、. CAUTION: DO NOT OPEN EITHER THE INLET OR EXHAUST VALVES RAPIMY AS THIS DISTURBS AND SCATTERS THE SAMPLE. f, Close the gas inlet tube of the bomb and remove pressure tubing. 5.4.3 Preparing the calorimeter water. a. Fill a clean 500 milliliter (mi) container with water and adjust the water temperat
20、ure to 18.5“C to 19.0C. Note: With the ambient temperature approximately 24OC, the water temperature will rise about 0.5“C from the time the water is drawn and the calori- meter is completely assembled. b, Pouring slowly to minimize splashing, transfer 450.0 grams 2 0.05 gram of water into the calor
21、imeter flask. Wipe off any water that may have splashed onto the upper portion of the flask. A medicine dropper will facilitate the final weight adjustment. 4 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-1454 MI 77799LL 0089762 5 I MI L-ST
22、D-1454 5 July 1971 5.4.4 Assembling the calorimeter. a. Connect the firing circuit to the bomb and lower the bomb into the water checking to see that the bomb is air tight. b. Place the cover on the calorimeter having the thermometer extend into the water. For uniformity, the thehometer should alway
23、s be submerged the same amount. A minimum immersion of 4-5/8 inch is reqoired and may be obtained in the Parr 1411 calorimeter by having the thermometer extend seven inches below the underside of the cover. !hen the parts are properly positioned, the thermometer should not touch the bomb, the stirre
24、r, nor the wall of the flask. 5.4.5 The test run. a. Operate the stirrer for at least three minutes before starting tem- perature readings. The same equilibrium period should be used for all tests to main tain uni f ormi ty . _. b. Arrange a timer or a clock uith a sweep second hand so that readings
25、 can be made at prescribed intervals during the test. c. Record the room temperature within one minute be one minute after TIR for verification of ambient conditions. I“ d. If a glass thermometer is used, tap it solidly w few seconds to insure that the mercury in the thermometer has ore Tg and withi
26、n th a pencil for a all settled downin the column before each reading. e. Although it is possible to determine the calorific value of a sample with only four measurements (water temperature at To, TG, Ti2 and Tia), it is recommended that a check be made on the uniformity of the system and the burnin
27、g rate of the sample by recording the water temperature at the following intervals in minutes starting from To: TO T8 Ti 1 T12 T3 T9 T11.25 T15 Tg T1 o T11.50 T1 8 .? T7 T11 .75 f. During the initial rating period, Tg minus T3 should be within 0.003C of T3 minus TO. the bomb. If the difference ia gr
28、eater than 0.003C, do not fire Begin timing again with a new To until the system is stable. g. h. Within ten seconds after Tg, the sample shall be fired by complet Readings at P7, Ts, T and TIO may be recorded to the nearest 0.0 the circuit. All others should be recorded to t 8 e nearest 0.001“C. 5
29、Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-L454 MI 77777LL 00877b3 7 I . MI L-STD-1454 5 July 1971 i. The 1/4 minute readings between Til and Ti2 are taken to examine for equilibrium before the final rating period begins. temperature dur
30、ing each 1/4 minute interval is not greater than 0.003C, it may be assumed that the sample burned completely during the interval between T6 and T12, thereby validating the use of the formula in 5.5.4 for radiation correction. j. As a check on the uniformity of the final rating period, T18 minus Ti5
31、should be within 0.002“C of Ti5 minus T12. If the average increase in k. At the completion of the run, exhaust the residual gases, empty the bomb, clean all parts and wipe dry in preparation for the next test. Also run a wire through the gas inlet tube to remove any foreign matter that could clog th
32、e gas passage. 5.5 Cal cul ations. 5.5.1 General requirements Subtracting T6 and Ti2 will give the temperature rise produced by combustion of the sample and fuse, but this includes several other thermal effects for which corrections must be made. In order to calculate the heat of combustion of the s
33、ample, it is necessary to determine the true tem- perature rise due only to combustion of the sample, excluding the heat from the fuse wire, the heat of stirring, and any heat gained or lost by interchange with the surroundings. calorific value of the sample are given in the following paragraphs (5.
34、5.2, 5.5.3, 5.5.4 and 5.5.5): 5.5.2 Thermometer scale correction. A correction must be applied to readings taken at T6 and Ti2 to compensate for variations in the thermometer bore and in the graduated scale. After applying these corrections, subtract T6 from Ti2 to determine the net cor- rected temp
35、erature rise. The thermometer is calibrated with the bulb and stem at the same temperature, but the calorimeter is operated with the bulb and a portion of the stem inside the calorimeter while the remainder of the stem is at a different temperature outside the Calorimeter. This requires the appli- c
36、ation of a stem correction (SC) calculated as follows: . The steps for calculating the true temperature rise and the These are indicated by the thermometerb calibration. 5.5.3 Emergent stem correction. SC = O.O0Of6(TJ2 - T6) (Ti2 + T6 - I“ - to) where.1 is the temperature at which the mercury level
37、in the thermometer is exactly the same as the water level in the calorimeter and to is the mean tempera- ture of the emergent stem during the calorimetric. test. It often can be assumed that to = Ti2 and if the thermometer extends seven inches below the underside of the cover in the Parr 1411 calori
38、meter, it can be assumed that 1 = 17.0, then Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-1454 MI m 7777711 0087764 9 I MI L-STO-14 54 5 July 1971 Example: Room temperature = 25C Ti2 = 23.012 T6 = 19.528 I“ = 17.0 SC = 0.00016 SC = 0.00016
39、 SC- = 0.0014 23 - 19.5) (19.5 - 17.0) 3.5) (2.5) Add the stem correction to the net corrected temperature rise. 5.5.4 Radiation correction. Since the calorimeter always is operated below room temperature, a correction must be applied to account for the heat which enters the calorimeter during the t
40、est. This can be determined in several ways, but for simplicity an empirical formula is suggested. experimental data and will be accurate for all mixtures which burn as fast or faster than the standard zirconium-barium chromate mixtures. The user is warned that this method may not be accurate for mi
41、xtures with extremely slow burning rates which produce time-temperature curves appreciably different from those obtained with the zirconium-barium chromate mixture. This is derived from Compute the radiation correction (RC) from the formula: RC = 5(T18 - T12) + (T6 - TO) 6 Subtract RC from the net c
42、orrected temperature rise. 5.5.5 Calculation of thermal value. The steps to be followed in computing the thermal value of the sample are summarized below. See Fiq. 2 for a sample data sheet and Fig. 3 for an example of a completed data sheet: a. Apply scale corrections to Tg and Ti2 b. Subtract T6 f
43、rom Ti2 c. Add the stem correction d. Subtract the radiation correction e. Multiply the resulting true temperature rise by the of the calorimeter to determine the total heat released in calor water equi val ent es. f. Subtract 1.13 calories (for 7cm Parr fuse wire) to account for the heat from the f
44、use wire. - g. Divide the weight of the sample in grams to determine the calorific value of the sample in calories per gram. 7 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MI L-STD-1454 5 July 1971 5.6 Calibration, 5.6.1 The calorimeter shall be c
45、alibrated (water equivalent established) with a standard sample of heat powder made expressly for calibration purposes and available from NBS, The address is: Office of Standard Reference Materials, National Bureau of Standards, Washington, D.C. 20234. The standard samples come in units containing 5
46、0 grams each. The following stocks have been made avail- able: “one unit of SRM 1651, Heat-Source Calorimetry Standard Reference Maferial “ for powder having a nominal heating value of 350 calories per gram; SRM 1652 for a nominal heating value of 390 calories per gram; or SRM 1653 for a nominal val
47、ue of 425 calories per gram. 5,6.2 Each calorimeter and its component parts will be uniquely identified and used only as a unit. Eachncalorimeter shall be associated only with the calibra- tion constant (water equivalent) determined for it as a unit. fication of the calorimeter required for calibrat
48、ion, but no modification shall be made after the calorimeter is calibrated. 5.6.3 A minimum of ten calibration determinations shall be run to establish the water equivalent; the standard deviation of the result shal be no more than 0.5 A standard deviation greater than.0.5 would indicate a lack of u
49、niformity in the equipment, ambient temperature, or the operator s procedure. 5.6.4 Each calorimeter shall be recalibrated either with ten determinations at six month intervals, or with two determinations at two week intervals, using con-. trol charts to monitor the data. .The shorter interval is preferable if the calori- meter is in constant use. Whichever time-cycle is observed, the water.equivalent shall b
