MIL-DTL-8789F
4.8.3.2 Oil aging. Samples shall be completely immersed in hydraulic fluid in accordance with
MIL-PRF-5606, MIL-PRF-83282 or MIL-PRF-87257at a temperature of 158°F ±2°F (65.6°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. The end fitting shall be visually examined for material (see 3.3),
4.9.2 Bulge resistance test. Hose assemblies when subjected to the bulge resistance test shall meet
the requirements of 3.6.1. 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 VIII.
c. The weight of the ball, in ounces, shall be no more than the hose size tested.
d. 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.
TABLE VIII. Hose inner tube diameter at the bulge.
A diameter 1/
Hose dash
min
size
inch (mm)
4
.146 (3.71)
5
.177 (4.50)
6
.271 (6.88)
8
.365 (9.27)
10
.455 (11.56)
12
.568 (14.43)
16
.778 (19.76)
1/ Diameter A, indicates both the minimum
permissible inner tube diameter at the bulge,
and the minimum nipple ID of the fitting, when
the fitting is assembled with the hose.
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