 |
|||
|
|
|||
| ||||||||||
|
|  4.6.11 Resistance to cold temperature. Mold a disc of cured compound approximately 2-
3/8 inches in diameter by 1/2 inch thick. Subject the thoroughly cured sample to -65F for
3 hours. Immediately upon removal from cold chamber, impact test the disc with a Gardner
impact tester using 150 inch-pounds impact. (Gardner Impact Tester, Variable, Cat. No. 1G-
1120, 160 inch-pound range, with a 4-pound rod as accessory.) Sample shall be examined for
signs of cracking, chipping, or other deterioration.
4.6.12 Compression set. The compression set of the material shall be determined in
accordance with ASTM D 395, method B, using 1.75 + 0.02 inches in diameter by 0.38 + 0.02
inch thick molded specimens, with the following exceptions:
a.
Specimens shall be heat treated at 160F for 48 hours.
b.
Additional specimens shall be subjected to -65F for 48 hours.
c.
Specimens shall remain at ambient temperature for 60 minutes prior to final
thickness measurements.
d.
Spacer bars shall be 0.250 + 0.002 inch thick.
4.6.13 Fast cookoff test. The thermally protected bombs loaded to the bomb sealing
suitability requirement of 3.3.3 shall be subjected to the fast cookoff test defined for
the Mk 82 Mod 2 Bomb by the Naval Weapons Laboratory, Dahlgren, Va.
4.6.14 Reactivity tests. The reactivity with H-6 and Tritonal explosives shall be
determined for each component and the final cured compound in accordance with vacuum
compatibility test procedures below.
4.6.14.1 Vacuum compatibility test. The vacuum compatibility test is carried out in
a glass unit, figure 1. The vacuum compatibility test chamber may consist of an aluminum
block or oil bath with thermo-regulator capable of maintaining a test temperature of 100
+ 0.5 centigrade (C) when testing with H-6 and Tritonal explosives.
4.6.14.1.1 Calibration of glass tube. Determine the volume in milliliters of the 15.5-
centimeter (cm) heating tube (Scientific Glass Apparatus, Cat. No. JV-6850 or equivalent)
by running in mercury from a burette until the tube is filled to the level at which the
ground glass joint of the capillary tube will make contact with the mercury. Subtract from
the indicated burette readings, the volume of explosive used in the test. The difference
shall be represented by the symbol A. Transfer 7.0 ml of mercury to the cup at the lower
end of the capillary tube. Clamp the tube in an upright vertical position and measure the
height in millimeters (mm) of the mercury column in the capillary tube (approximately 25
mm). Measure the length in millimeters of each of the three parts of the capillary tube and
add these values to obtain total length. From the total length subtract the height of the
mercury column in the cup as previously obtained. Represent this difference by the symbol
B1 From the total length subtract the height of the column of mercury in the cup measured
at the end of the test described in 4.6.14.1.2. Represent this difference by the symbol B.
Determine the capacity of the capillary tube per unit of length as follows: Transfer an
accurately weighed sample of approximately 10 g of mercury to the cup at the lower end of
the capillary tube. Manipulate the tube so that when it is horizontal, mercury is contained
in a continuous section of the longest part of the tube and measure the length of the
mercury column. Repeat this twice with the mercury in two other parts of the long section
of the tube. Calculate the average of the three measured lengths of the mercury column.
Represent the unit capacity in ml/mm of the capillary tubing by the symbol C. This can be
obtained from the formula:
C=
W
DL
where:
C
=
unit capacity of capillary tubing, ml/mm
W
=
weight of mercury, g
D
=
density of mercury at temperature of determination, g/ml
L
=
average measured lengths of mercury column, mm.
4.6.14.1.2 Test procedure. Use 2 N + 1 (where N equals the number of explosives used)
tubes similar to the heating tube portion of the apparatus shown in the va uum compatibility
c
test method. For controls, add 0.2 g of the inert compound to one tube and 0.2 g of each
explosive to additional individual tubes. Place uniform mixtures of 0.2/0.2 g of the inert
compound and each of the explosives specified in the test in single separate tubes. Clamp
the apparatus so that the long section of the capillary tube is in a nearly vertical
position. Transfer 7.0 ml of mercury to the cup at the lower end of the capillary tube.
Connect a vacuum pump to the lower end of the capillary tit be and evacuate the system until
the pressure is reduce to approximately 5 mm of mercury. (Evacuation of the capillary tube
|
|
Privacy Statement - Press Release - Copyright Information. - Contact Us |
Click
here for thousands of PDF manuals