MIL-PRF-19004B
a.
Blank flanges (one with air supply and gauge connections) shall be
bolted to gasketed fan flanges.
b.
Air at a pressure 50 percent higher than the maximum pressure
capability of the fan shall be supplied to the casing interior.
A pressure drop in a 10-minute period that exceeds 5 percent of the test
pressure is cause for rejection.
4.7.9 Speed. The fan-motor unit shall be operated at each speed at free
delivery to determine whether the motor speed is at least 97 percent of the
design speed at rated voltage (see Table II). A speed of less than 97 percent
of the design speed is cause for rejection.
4.8 Composite material testing. Composite material shall be tested for flame
spread, smoke obscuration, combustion gas igniteability, heat release, and
mass consumed.
4.8.1
Fan casing and conduit box.
4.8.1.1 Internal fire test. Fan casing and conduit box material shall be
subjected to an internal fire insult as described in the full-scale Factory
Mutual test for horizontal duct FM-4922 with modifications see (Figure 3).
4.8.1.2 External fire test. Fan casing and conduit box material shall be
subjected to an external fire insult as outlined in Figure 4. Temperatures
around outside of test specimen shall exceed minimum temperatures prescribed
by ASTM-E-119 for at least 15 minutes.
4.8.1.3 Acceptance criteria. Acceptance criteria for casing material shall
be in accordance with Table I of MIL-STD-2031.
4.8.2 Internal composite materials. Fan impeller, vanes, and motor composite
materials shall meet the smoke obscuration (ASTM-E-662) test as follows:
Ds During 300 Sec (flaming)
6 (4 minutes)
Ds During 300 Sec (nonflaming)
1 (4 minutes)
Dmax (flaming)
81
Dmax (nonflaming)
32
and the Combustion Gas (ASTM-E-800) test as follows:
Combustion Gas
Flaming
Non-flaming
CO
75
10
CO2
2.0%
0.4%
HF
<1
<1
HCl
13
1
NOx
1
<0.5
SO2
<1
<1
HCN
1
<1
NH3
<3
<3
COC2
<0.1
<0.1
4.9 Permeability tests. A permeability test on nonmagnetic material used in
construction of fans shall be conducted in accordance with MIL-STD-2142, Test
501 (see 3.2.4).
4.10 Maintainability demonstration. The first production unit shall be
examined after testing, and the capability to maintain, disassemble, and
repair the unit shall be demonstrated. The demonstration shall be conducted
utilizing the recommended tools and with other than expert mechanics.
Evidence that maintainability of the fan-motor assembly cannot be accomplished
by other than expert mechanics shall be cause for failure of the
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