MIL-DTL-26633E
6. NOTES
(This section contains information of a general or explanatory nature that may be helpful, but is not
mandatory.)
6.1 Intended use. The hose assembly covered by this specification is intended for use as a servicing
hose on aerospace ground servicing 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 3,000 psig (206.84 bar) at temperatures ranging
from -65°F to +160°F (-53.89°C to 71.11°C).
6.1.1 Oxygen system cleanliness needs. This specification does not specify cleanliness levels.
Users are cautioned that the hose assembly should be cleaned to their 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.
6.1.2 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 system operation.
6.1.3 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.
6.1.4 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, therefore, they are not be
used in oxygen systems or near oxygen systems where they could be consumed in a fire.
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