MIL-DTL-27166F
direction at the specified reseal pressure when tested as specified in 4.6.1.2. The actual reseal
pressure will be equal to or greater than the specified reseal pressure.
3.6.1.1 Leakage.
Types I and II valves shall not leak at a rate of 0.061 cubic inch (1 cubic centimeter) of standard
air per minute or more in the reverse flow direction at a pressure differential of 10 psi (68.9 kPa)
when tested as specified in 4.6.1.2.
3.6.2 Cracking.
The valve cracking pressure shall be greater than the specified reseal pressure by a value that
is within the pressure offset range specified below. The valve cracking pressure offset range is
determined by the specified reseal pressure.
Specified Reseal Pressure Range
Cracking Pressure Offset Range
0.00 1.00 psi (0.0 6.9 kPa)
0.00 0.50 psi (0.0 3.4 kPa)
1.01 1.50 psi (6.9 10.4 kPa)
0.00 0.75 psi (0.0 5.2 kPa)
1.51 3.00 psi (10.4 20.7 kPa)
0.00 1.00 (0.0 6.9 kPa) psi
3.01 psi and greater (20.8 kPa and greater)
0.00 1.50 psi (0.0 10.3 kPa)
3.6.3 Minimum flow rate.
The valve minimum flow rate shall be specified by the using activity (see 3.6.3.1 and 6.2). When
tested as specified in 4.6.1.2, the valve minimum flow rate shall be determined at a differential
pressure of 1.5 psi (10.3 kPa) greater than the specified reseal pressure in the flow direction.
3.6.3.1 Minimum flow rate calculations.
Calculations shall be made as follows, by the valve using activity, to determine the minimum
flow rate required to protect the container (see 6.2):
ft3/minute (m3/minute) = (Vc Vm) 0.12
Minimum flow rate
Vc = Volume of container ft3 (m3)
Where:
Vm = Volume of material in container ft3 (m3)
3.6.4 Operating life.
The valves shall withstand 2500 cycles at ambient conditions from the closed position to the
open position for either or both positive and negative pressure differentials, as applicable for the
type concerned.
3.6.5 Environmental tests.
The valves shall be capable of withstanding the following environmental conditions when tested
as specified in 4.6.3.
3.6.5.1 Temperature.
The valves shall be capable of withstanding without degradation of performance attributes,
temperatures ranging from -80 to +160 °F (-62 to +71 °C) during operation and nonoperation.
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