MIL-PRF-87961 Hose And Hose Assemblies, Air Duct, Air Breathing, Oxygen SystemThis specification covers the requirements for hose and hose assemblies \(see 6.9\) which supply breathing oxygen to aircrews during the operation of high performance aircraft.

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MIL-PRF-87961B

3.5.3 Cleanliness. All surfaces shall be free of visible particulates (50 microns and

larger), free of visible fluorinated lubricants, and free of hydrocarbon contamination to a level

not greater than 3 milligrams per square foot (mg/ft2) (see 6.5).

3.5.4 Flexibility. The hose shall withstand being coiled around a 1.75 inch diameter rod,

and then twisted 360o or 720o for hoses under or over 30 inches in length, respectively, in each

direction about the longitudinal axis.

3.5.5 Delamination. Under a vacuum, the inner layer of the hose shall not delaminate.

3.5.6 Elongation. When suspended in the vertical position with a load, the hose

elongation shall be between 3% and 10% of the original length. Any permanent set (see 6.9)

shall not exceed 5% of the original length.

3.5.7 Leakage. The hose shall not leak in excess of 0.25 cm3 per minute per foot of hose,

when pressurized to 10 psi gage (psig).

3.5.8 Tensile load. The hose assembly shall withstand a 40 pound tensile load.

3.5.9 Static load. Under a static load of 125 pounds per 4 inch section, the outside

diameter shall not be decreased more than 15% of the original value. After removal of the static

load, the outside diameter of the hose shall be within 5% of the original outside diameter.

3.5.10 High temperature. The hose shall withstand exposure to 160o +5oF for 48 hours.

3.5.11 Low temperature. The hose shall withstand exposure to -40o +5oF for 30 minutes.

3.5.12 Abrasion. The hose shall withstand abrasion simulating usage (see 6.6).

3.5.13 Flexibility endurance. The hose shall withstand 500 cycles of being coiled and

released around a rod, 1.75 inch diameter, and then 500 cycles of being twisted 270o about the

longitudinal axis in both directions.

3.5.14 Burst pressure. The burst pressure of the hose shall exceed 20 psi (see 6.9).

3.5.15 Age. The hose shall be no more than 12 months old from the cure date to the

acceptance date, as defined in SAE-AS1933.

3.5.16 Weight. The hose shall not exceed 5.0 ounces per foot of length.

3.5.17 Identification. The hose shall be permanently and legibly marked with the

following data (see 6.2):

a. Nomenclature

b. Cure date.

c. PIN.