Section 2.
CLEANING PROCEDURES
1.
CLEANING PROCEDURES. There is considerable controversy about the
proper procedures for cleaning hyperbaric installations and their piping
systems. In addition to the basic esthetic and practical need for a clean
working environment, there are two main reasons for cleaning hyperbaric
systems. The first is to provide a life supporting, non-toxic atmosphere for
the chamber occupants and the second is to remove all traces of combustible
material, with special emphasis on the removal of hydrocarbons from all
systems which will contain high concentrations of oxygen. Extreme
cleanliness in oxygen systems is necessary because experience has shown that
even slight traces of hydrocarbons can result in a very destructive fire or
an explosion. Both needs are equally important and are met by proper
cleaning of the breathing gas system and the piping and gas storage systems
of the hyperbaric chamber air system.
2.
BREATHING GAS SYSTEM. The procedures for cleaning a system for safe
breathing gas are vastly different from procedures for cleaning an oxygen
system. A lack of understanding of this difference in required cleaning
procedures has frequently resulted in a considerable waste of time, manpower,
and money.
When a breathing gas system is being cleaned, bear in mind that the method of
cleaning must not damage the cleaned system and the gas coming from the
cleaned system must conform to the current U.S. Navy Diving Manual, NAVSEA
0994-LP-001-9012, (see Reference (1)) standard for breathing air quality, as
listed in Table 12-7.
TABLE 12-7
Standard for Divers Breathing Air
Oxygen
20 to 22% by volume
Carbon Dioxide
1,000 ppm max. (0.05% by vol.)
Carbon Monoxide
20 ppm max.
Oil Mist & Vapor
5 mg/m3 max.
Total Hydrocarbons
25 ppm
(expressed as methane but
excluding methane)
Odor
Not objectionable
Particulates
Not detectable except as noted
above under oil
mist & vapor
In addition to the specifics of Table 12-7, Table 12-8, from NAVSHIPS 0938-
011-4010, Nuclear Powered Submarine Atmosphere Control (see Reference (2)),
lists about 40 items for which concentration limits have been established and
which might possibly be present in a breathing gas system. To insure an
acceptable level of compressed breathing air for divers, the Navy has
established by NAVSEA NOTICE 9597 of 27 May 1977 a semiannual sampling
program. For further information about this program, contact the Naval Air
Test Center Program at the Naval Coastal Systems Center, Panama City,
Florida, phone (904) 234-4482.
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