MIL-DTL-11352K(AT)
4.6.4 Operating environmental requirements verification.
4.6.4.1 Temperature fluctuation resistance. To determine conformance to 3.7 1, the
vision block shall be subjected to a temperature of -54±3 °C (-65±5 °F) for 12 hours and shall
then be stabilized at room temperature and placed in an oven for a period of 12 hours with the
oven temperature stabilized at 71±2 °C (160±3 °F). The vision block shall then be removed
from the oven, stabilized at room temperature and examined for defects. Upon examination,
samples that pass this test shall be subjected to the test specified in 4.6.4.9.
4.6.4.2 Low temperature. To determine conformance to 3.7.2, the vision block shall be
placed in a temperature chamber in a manner that will simulate its actual use, and the following
steps shall be performed:
a. The internal chamber temperature shall be lowered to a storage temperature of -54 °C
(-65 °F) and maintained for a period of 24 hours after stabilization.
b. The internal chamber shall be adjusted to the lowest temperature under which the
vision block is designed to be used and maintained until temperature stabilization is
reached.
c. The vision block shall be returned to standard ambient conditions and stabilized.
d. The vision block shall then be tested as specified in 4.6.3.1, 4.6.3.2 and 4.6.3.3 and
shall be checked for any indication of moisture, bond separation or other defects.
e. At the conclusion of this test, the vision block shall be returned to 23±10 °C
(73±18 °F).
NOTE: The rate of temperature change (steps a, b, and c) may be the maximum obtainable by
the chamber, but shall not exceed 10 °C (18 °F) per minute.
4.6.4.3 High temperature. To determine conformance to 3.7.3, the vision block shall be
exposed to a hot and dry temperature profile shown in table V for a total period of 72 hours
divided into three 24 hour cycles. The humidity during test shall be less than 10%. After the
exposure to the temperature profile, the vision block shall be stabilized at 60 °C (140 °F) and
then tested, as specified in 4.6.3.1, 4.6.3.2, and 4.6.3.3 and checked for any moisture, bond
separation or other defects.
4.6.4.4 Basic shock. To determine conformance to 3.7.4, three shocks in each direction
shall be applied along three mutually perpendicular axes of the vision block (total of 18 shocks).
The shock pulse shape shall be of a sawtooth form in accordance with figure 1, of amplitude 40 g
and a time duration of 11 ms. At the conclusion of the test, the vision block shall be tested as
specified in 4.6.3.1, 4.6.3.2 and 4.6.3.3 and checked for any physical damage.
4.6.4.5 Gun fire shock. To determine conformance to 3.7.5, three shocks in each
direction shall be applied along three mutually perpendicular axes of the vision block (total of
18 shocks). The shock pulse shape shall be half sine wave form in accordance with figure 2 of
amplitudes and duration as specified in table VI. At the conclusion of the test, the vision block
shall be tested as specified in 4.6.3.1, 4.6.3.2 and 4.6.3.3 and checked for any physical damage.
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