The hose assemblies covered by this specification are intended for use as flexible manifold connections on ground servicing equipment supplying breathing oxygen to aerospace equipment. The use is military unique in its intended application the hose assembly will be used in charging aerospace vehicle breathing oxygen systems and must be able to operate satisfactory with a nominal working pressure of 2,400 psig (165.47 bar) in the operating temperature range from -65°F to +160°F (-53.89°C to +71.11°C).

Oxygen system cleanliness needs. This specification specifies cleanliness in accordance with SAE AS611, class II. Users are cautioned that the hose assembly should be evaluated to their cleanliness requirements before installing in any equipment. Only qualified technical personnel with knowledge for the selection of cleaning methods for oxygen rich environments should make the determination as to what cleanliness level is acceptable for their application.

Cleaning a component or system for oxygen service. Cleaning a component or system for oxygen service involves the removal of combustible contaminants, including the surface residue from manufacturing, hot work, and assembly operations, as well as the removal of all cleaning agents. These cleaning agents and contaminants include solvents, acids, alkalis, water, moisture, corrosion products, non-compatible thread lubricants, filings, dirt, scale, slag, weld splatter, organic material (such as oil, grease, crayon, and paint), lint, and other foreign materials. Injurious contaminants can be removed by cleaning all parts and maintaining this condition during construction; by completely cleaning the system after construction; or by a combination of the two. The prevention of recontamination before final assembly, installation, and use is essential to safe oxygen systemoperation.

Potential ignition energy mechanisms. Safe use of oxygen requires the control of potential ignition energy mechanisms within oxygen systems by maintaining scrupulously clean systems. Cleanliness (contamination control) is critical in oxygen components and systems. Contamination can cause ignition of components or systems by a variety of mechanisms, such as particle impact, mechanical or pneumatic impact, or spontaneous ignition. In an oxygen environment, contaminants increase the ignitability of both metallic and nonmetallic materials. 

Restricted materials.

a. Cadmium: The toxicity and vapor pressure of cadmium restrict its use.

b. Titanium: Titanium metal is not be used with liquid oxygen at any pressure or with gaseous oxygen or air at oxygen partial pressures above 30 psig. Titanium and its alloys are impact sensitive in oxygen.

c. Magnesium: Magnesium metal is not be used in oxygen systems. In addition, its alloys are not to be used except in areas with minimal exposure to corrosive environments. Reactivity with halogenated compounds constrains its use with lubricants containing chlorine and fluorine.

d. Mercury: Mercury is not be used in oxygen systems in any form because it is toxic; in addition, it and its compounds can cause accelerated stress cracking of aluminum and titanium alloys.

e. Beryllium: Beryllium and its oxides and salts are highly toxic and are not be used in oxygen systems or near oxygen systems where they could be consumed in a fire.