MIL-PRF-25478D
TABLE II. Pressure drop data
Type IA
Type IA
Type IB
Type IB
Type II
with
without
with
without
with/without
temperature
temperature
temperature
temperature
temperature
regulation
regulation
regulation
regulation
regulation
Chill
-30o ±2oF
-30o ±2oF
-65o ±2oF
(see note 1)
(see note 1)
Temperature
Chill
24 hours
24 hours
24 hours
24 hours
72 hours
Duration
Rated Air Flow (see note 3)
(see note 3)
(see note 2)
(see note 2)
(see note 2)
Temperature of
-30o ±2oF
100o ±2oF
-30o ±2oF
100o ±2oF
-65o ±2oF
rated air flow
Rated Oil Flow (see note 4)
(see note 4)
(see note 4)
(see note 4)
(see note 4)
Temperature at
225o ±2oF
225o ±2oF
225o ±2oF
225o ±2oF
325o ±5oF
oil inlet
Maximum
185oF
185oF
185oF
185oF
285oF
temperature at
oil outlet
Maximum
30 psi
25 psi
30 psi
25 psi
(see note 5)
pressure drop
Notes: 1. Chilling not required, Stabilize at ambient temperature for 24 hours.
2. Rated air flow shall be provided by the acquisition document (see 6.2).
3. Double the rated air flow as provided by the acquisition document (see 6.2).
4. Rated oil flow shall be provided by the acquisition document (see 6.2).
5. Unless otherwise specified in the acquisition document (see 6.2), the pressure drop
across the oil cooler shall not exceed 20 psi.
4.6.5 Pressure drop without air flow. The oil pressure drop without air flow test shall be
conducted at rated oil flow, as specified in the acquisition document (see 6.2). Unless otherwise
specified in the acquisition document (see 6.2), Type IA and Type IB oil coolers shall be tested
at oil inlet temperatures of 145°, 180°, 210°, and 240° ± 2°F. Type II oil coolers shall be tested at
oil inlet temperatures of 145°, 205°, 265° ± 2°F, and 325° ± 5°F. The oil pressure drop across
the oil cooler shall be compatible with the maximum allowable pressure for the engine oil
scavenging pump system as specified in the acquisition document (see 6.2). Unless otherwise
specified in the acquisition document (see 6.2), the oil pressure drop through the bypass warm-up
passage shall not exceed 8 psi.
4.6.6 Pressure resistance. With an oil temperature of less than 100°F and the bypass
warm-up passage closed, the flow of oil through the oil cooler shall be adjusted so that an oil
pressure drop of 80 psi occurs from the oil inlet of the cooler to the oil outlet of the cooler. The
oil outlet pressure shall be maintained at 10 psi maximum. There shall be no leakage or
distortion.
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