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Storage and operating temperature. |
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|  MIL-M-70542 (AR)
4.7.5.3 Mechanical inspection. The mechanical parts of the MBD
shall be inspected for broken parts, completeness, workmanship and
functionability. The locating block shall be checked for freedom and
smoothness of operation. Paint chips or nicks which do not effect the
function of the instrument shall be touched up. All burrs and excess
material shall be removed from castings and forgings. All surfaces
including threads, shall be free from burrs and sharp edges.
4.7.6 Interchangeability.
4.7.6.1 Interchangeability fixture. The ability to insert the
MBD into the test fixture P/N 9364922 barrel or gun tube confirms the
interchangeability of the device.
4.7.7 Purging. This portion of the test shall be performed
utilizing dew point tester, type 7000 or equivalent. The MBD shall be
purged with dry nitrogen for a period of time until it is determined
that the dew point is at least -25 degrees at atmospheric pressure.
Suitable valve adapters shall be used to facilitate this test. The
unit shall be sealed immediately after purging.
4.7.8 Sealing. This test shall be performed utilizing a
suitably calibrated pressure gage. Suitable valve adapters shall be
used to facilitate the test. Care will be utilized to keep the MBD
internal atmosphere purged. The MBD shall be pressurized with dry
nitrogen to 5 plus or minus .1 psi for a minimum of one hour. There
shall be no evidence of leakage in excess of 0.1 psi. Prior to ship-
ment the unit will be sealed at a presure of between 0.25 and 0.50
PSIG.
4.7.9 Environmental sampling. Three MBD's shall be selected at
random from each 50 produced, or from each months production,
`whichever occurs first. Each sample shall meet the requirements and
tests in Table IV.
4.7.10 Test methods and procedures.
Prior to environmental, the MBD shall have met the
Note:
examination and tests in Table II.
4.7.10.1 Storage and operating temperature. The test equipment
utilized in this test shall be in accordance with "Test Facilities*'
requirements of MIL-F-13926. The uncased MBD shall be placed in the
test chamber and the temperature of the test chamber raised gradually
(rate of temperature change in the test chamber shall not exceed 10
degrees C per hour throughout the temperature cycling test) to 65
degrees C. The MBD shall remain at this temperature for a minimum of
three hours. At the completion of this period and while at 65 degrees
C, the MBD locating block shall be depressed three times and observed
to return to its original position each time. Upon completion of this
test, the temperature of the test chamber shall be gradually raised
(see above rate of temperature change) to 71 degrees C.
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