MIL-STD-1622 Cleaning of Shipboard Compress
MARE ISLAND NAVAL SHIPYARD Process Instruction 0516-839
CHARLESTON NAVAL SHIPYARD Process Instruction 0558-839-701
MIL-D-16791 Detergent, General Purpose (Liquid Non-Ionic).
Additionally, an excellent review of several cleaning methods is available in
NAVMAT P-9290, System Certification Procedures and Criteria Manual for Deep
Submergence Systems (see Reference (4)).
ACCEPTABLE CLEANING AGENTS. There are two principal cleaning agents
which are used in most of the recommended practices.
Trisodium Phosphate. Trisodium phosphate is one of the best
cleaning agents for through system flushing methods. Although it is very
caustic in strong concentrations, it is readily removed from a system by a
warm water flush and trace amounts which may remain in the system are not
toxic and do not promote the development of any secondary toxic substances.
BUSHIPS 9230.12 describes an approved procedure for using this agent.
Trichlorotrifluoroethane. It is suggested that MIL-STD-1330 be
used as a general guideline for generating cleaning procedures in conjunction
with this agent. It is a liquid at normal temperatures with a boiling point
of 118 deg. F at one atmosphere. The agent itself is only slightly toxic at
atmospheric pressures and does not have a deleterious effect on metal
systems. This agent, however, in the presence of a CO-H2 burner does break
down into hydrogen chloride (HCL) and hydrogen fluoride (HF) gas. The
production of these two components would give rise to both a toxic problem
and a corrosive problem in the concentration range of one ppm by volume.
Another difficulty encountered is incompatibility with synthetic materials
such as nylon, tygon, rubber, plastic, and other materials that may be used
in a typical breathing gas system.
UNACCEPTABLE CLEANING AGENTS. Two materials, trichloroethylene and
methyl chloroform, frequently used in cleaning operations, must not be used
for cleaning breathing gas systems. They present a potential hazard in that
a chemical reaction which yields dichloroacetylene occurs when they are
passed through a moderately heated alkali (CO2 removal chemicals).
Dichloroacetylene is an extremely toxic compound which must be excluded from
closed atmospheres. Unfortunately, no analytical method is available for the
direct analysis of dichloroacetylene in a complex atmospheric mixture at the
required low levels of 1 ppm or less. Therefore, the use of substances
which may develop dichloroacetylene must be avoided.
CLEANING DOCUMENTATION. As mentioned at the beginning of this chapter,
any reasonable method may be used for cleaning a hyperbaric system provided
it achieves the required level of cleanliness as proven by proper qualified
testing methods. Whatever method is used, it should be in accordance with
written procedures and all procedures and results must be recorded.