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|  MIL-F- 14252 ( AR )
4. 3.8.1 Procedure I. - The equipment shall be mounted In the
test chamber to simulate installation conditions. The rain
0
test chamber temperature shall be maintained between 20 C to
8
30C ( 68F to 86 F) throughout the test period. A simulated
rainfall of 4 / l.- 0 inches per hour as measured at the sur-
face of the equipment with a U. S. Weather Bureau type gage
shall be produced by means of a water spray nozzle of such
design that the water Is emitted In the form of small drop-
lets rather than a fine mist. The terngerature of the water
shall be maintained between llC to 20 C (52F to 68F). The
rainfall shall be dispersed uniformly over the test area within
the limits as specified above. Direction of rainfall shall be
0
variable from vertical to 45 from vertical in any direction.
The simulated rainfall shall be directed on all surfaces which
are normally subJected to rain. Duration of the test shall be
2 hours at the completion of which the equipment shall be
examined for evidence of water penetration or damage.
4.3.8.2 Procedure II. - Equipment shall be mounted In a test
chamber and exposed to.a simulated 24 hour rainfall totaling
I
32 inches made up of the following intensities with the indi-.
cated durations and other properties, both air and rain, at
0
0
21 C (70 F)
q
2
11 2
12
7
Amount (In. ) 1
1:00
0.05
11:00
11:55
Duration (hr:min. )
24
1
1
Rate ( in/hr)
7
3.2
4.0
2.25
2.55
Drop Size(mm) Min.
18
1.68
1,1
0.77
Std Dev.
I
18
25.1
26
Min. ht. of fall(rt) 18
4.3.9 Sand and dust 3 . . The equipment shall be placed within
the test chamber and the sand and dust density raised and maQt-
talned at 0.1 to 0.5 grams per cubic foot within the test space.
The relative humidity shall not exceed 30 percent at any time
during the test. Sand and dust used in the test shall be of
angular structure and shall have characteristics as follows:
1 As measured at the surface of the equipment. with a U. &
Weather Bureau type gage.
2 Wind speed of 40 mph during this portion of the cycle.
3 This test may be used as a substitute for driving snow.
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