MIL-DTL-28693 Hose, Rubber, Oil And Gasoline Discharge, Smooth Bore, Lightweight Buoyant Type, Longitudinally Reinforced, 6 InchThis specification covers a hose, rubber, oil and gasoline discharge, smooth bore, lightweight buoyant type, longitudinally reinforced, 6 inch furnished with couplings and a hose support ring. The system is intended for use as part of a buoyant fueling system. The maximum working pressure of this hose is 150psi \(1 MPa\).

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MIL-DTL-28693A

d. This test shall be performed after the hose has been equipped with couplings (see 3.5.1) to

determine conformance to 3.6.5. (Suitable precautions shall be taken to protect operators

from injury during the test in case the couplings are blown off or the hose ruptures).

4.7.6 Burst pressure (see 3.6.6). A section of hose obtained in accordance with 4.5.3.2 shall be

equipped with couplings and the burst pressure of this section in the straight conditions shall then be

determined in accordance with ASTM D380 to determine conformance to 3.6.6

4.7.7 Tensile pull and elongation (see 3.6.7 and 3.6.7.1). A section of hose when subjected to

tensile and pull elongation shall meet the requirements of 3.6.7. The following details shall apply:

a. The hose section obtained in accordance with 4.5.3.3 shall be equipped, on each end, with

couplings conforming to MIL-C-24356.

b. The ends of the couplings on the hose shall be adapted for testing in tension in a universal-

testing machine.

c. Two bench marks, 1 inch (25.4 mm) apart and 5-1/2 inches (14 cm) from each end of the

hose between couplings shall be marked on the outside (cover) for measuring elongation.

d. The section of hose with couplings shall be subjected to a tensile load of 6,000 lbs (2721.55

kg) in the axial direction and held at that load while the increase in distance is marked.

e. This measurement and the original measurement shall be used to calculate the elongation

percent for conformance with 3.6.7.

f. The tensile loading shall be increased to 12,000 lbs (5443.11 kg)and held at that load for 5

minutes while the hose is inspected for damage or weakening of the coupling grips.

g. The tensile loading shall be released and the hose allowed a period of 10 minutes to return to

normal, at which time it shall be visually inspected.

h. The hose shall be rejected if the inspection reveals visible damage, such as wrinkling or

bubbling of the cover or interior tube, an increase in length in excess of 1.5 percent, or other

visible indications of structural failure or delamination of the hose components.

i. The tensile load shall then be reapplied and increased until failure occurs.

j. The failure load and the type of failure, (i.e., hose break or coupling pullout) shall be recorded.

k. The rate of loading for the elongation and tensile tests shall be 1.0 inch (25.4 mm) per

minute.

4.7.8 Flexibility test (see 3.6.8).

a. The specimen for this test shall be a 12-inch (30.5 cm) section with square-cut ends obtained

in accordance with 4.5.3.1.

b. The load shall be applied perpendicular to the longitudinal direction of the specimen by

means of two plates, which evenly distribute the applied load over the entire specimen.

c. The hose specimen shall be compressed at a rate of 1 inch per minute until the applied load

has reached 100 lb �2 lb (45.4 kg � 0.91 kg) force.

d. Within 15 seconds after this load, the distance between the two plates shall be measured.

e. The distance between the plates shall not exceed 2-1/2 inches (6.35 cm).

4.7.9 Properties of rubber components (see 3.4.2). To determine conformance to 3.4.2, the

properties of rubber components, except the swelling in test fuel of the friction rubber on the reinforcing

fabric, shall be determined as follows:

a. Samples shall be longitudinal specimens prepared from the hose section obtained in

accordance with 4.5.3.2.

b. After separating and buffing smooth, the tube and cover samples shall be permitted to rest no

less than 30 minutes before preparing test specimens.