MIL-DTL-8790F
4.8 Preparation of specimens.
4.8.1 Hose assemblies. Test samples shall be assembled with samples of hose and fittings of
applicable size in accordance with MIL-DTL-8788 and MIL-DTL-8789, respectively. Assembly lengths
shall be as shown in table I.
4.8.2 Test fluid. Unless otherwise specified, the test fluid shall be lubricating oil grade 50 in
accordance with SAE-J1966 or hydraulic fluid in accordance with MIL-PRF-5606, MIL-PRF-83282,
MIL-PRF-87257 or water.
4.8.3 Aging of samples. When specified, specimens shall be either air aged (see 4.8.3.1) or oil aged
(see 4.8.3.2) prior to testing.
4.8.3.1 Air aging. Samples shall be exposed to air at a temperature of 158°F ±2°F (70°C ±1.11°C)
for a minimum of 168 continuous hours.
4.8.3.2 Oil aging. Samples shall be completely immersed in fluid in accordance with MIL-PRF-5606,
MIL-PRF-83282, or MIL-PRF-87257 at a temperature of 158°F ±2°F (70°C ±1.11°C) for a minimum of
168 continuous hours. Air shall not be trapped in the bore of the tube during this aging period. The
volume of fluid used shall be sufficient to completely fill and cover the samples. Both the samples and
the fluid shall be placed in a non-pressurized closed type container or in a reflux type condenser to
prevent distillation of the volatile matter in the fluid. For qualification tests, a new batch of oil shall be
used for each group of test samples. For quality conformance tests, a new batch of oil shall be used for
each 10 or fewer tests.
4.9 Test methods.
4.9.1 Examination of product. Each hose assembly shall be carefully examined visually to determine
conformance to this specification with respect to materials (see 3.3), identification marking (see 3.8), age
4.9.1.1 Cleanliness inspection. Both ends of the hose assembly shall be visually inspected to
determine if caps or plugs are installed at the fittings. The caps or plugs shall then be removed and a
light source shall be placed at one end of the hose assembly. The interior of the hose shall be visually
examined, without magnification, from the opposite end of the light source. If the length of the hose
assembly precludes this, then examination shall be from one end of the hose assembly.
4.9.2 Bulge resistance test. Hose assemblies when subjected to the bulge resistance test shall meet
the requirements of 3.7.1. The following details shall apply:
a. Four hose assembly samples that have been prepared for the impulse test (see 4.9.6) shall be
checked for bulging of the inner tube and reduction of fitting nipple inner diameter caused by the
attachment of end fittings. Measurements shall be taken on assemblies using a ball-end type
gage.
b. The diameter of the ball shall not be less than .002 inch (0.05 mm) but no greater than .001 inch
(0.03 mm) smaller than the bulge diameter "A" specified in table V.
c. Without using force or lubrication, the ball shall be placed inside the end of the assembly at the
bulge gage inspection point shown on figure 1.
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