Chapter 6REFRIGERATION AND AIR CONDITIONING
slowly. If the valve is leaking, the pressure will
build up rapidly until it equals the inlet pressure.
7. Again loosen the gage to permit leakage at
the gage connections. Remove the thermal ele-
ment, or control bulb, from the crushed ice and
warm it with the hand or place it in water that
is at room temperature. The pressure should
increase rapidly, showing that the power element
has not lost its charge. If there is no increase in
pressure, the power element is dead.
8. With high pressure showing on both gages
as outlined above, the valve can be tested to deter-
mine whether the body joints or the bellows leak.
This can be done by using a halide leak detector.
When performing this test, it is important that
the body of the valve have a fairly high pressure
applied to it. In addition, the gages and other fit-
tings should be made up tightly at the joints so
as to eliminate leakage at these points.
present in various combinations in the compound.
You may be more familiar with their brand or
trademark names such as: Freon(s), Gentron,
Genesolv D, Frigen, AFFF, or carbon
tetrachloride. As Enginemen, we work with these
refrigerants, solvents, and fire extinguishing com-
pounds regularly aboard ship. The extended and
routine usage of halocarbons in the military and
civilian environments (e.g., home/car air condi-
tioners) has led us to a false sense of security which
makes us forget the inherent poisonous nature of
halocarbons, particularly when used in high con-
centrations in enclosed or confined spaces.
REPLACEMENT OF A VALVE
When an expansion valve is defective, it must
be replaced. Some valves used on naval ships have
replaceable assemblies and it is possible to replace
a faulty power element or other part of the valve
without having to replace the entire assembly.
When replacement of an expansion valve is
necessary, replace the unit with a valve of the same
capacity and type.
Warnings, hazards, and cautions in technical
and training publications are usually benign. The
labeling of containers and storage areas are con-
sistently inadequate. The procedures for the
disposal of halocarbon waste are not well known
nor are they followed. Most people do not know
the physiological effects of high concentrations
of halocarbons on humans or the recommended
first aid by both medical and non-medical
In addition to the maintenance of the com-
ponents described above, there are other parts of
the system that will need periodic maintenance to
keep the plant operating properly.
Vibration may cause leakage in the piping
system, allowing air and moisture to be drawn in
or there may be a loss of the refrigerant charge.
If this happens, the plant will operate erratically
and inefficiently until the cause of trouble is
All Enginemen who handle or use halocarbons
must be aware of the hazardous properties of
halocarbons. The greatest hazards have been
associated with Freon 113 refrigerant and
Genetron 113 (a fluorocarbon compound), with
the chemical name of TRICHLOROTRI-
FLUOROETHANE, which is used in large quan-
tities for cleaning refrigeration, hydraulic, air and
oxygen systems, and as a solvent for removing oil
and grease from machinery. Trichlorotri-
fluoroethane is a heavy, colorless liquid at room
temperature, and has an odor similar to dryclean-
ing fluid. Because of its low boiling-point it
evaporates rapidly at room temperature. Its vapor
is several times heavier than air and tends to col-
lect in low places.
Halocarbons are organic chemical compounds
containing one or more atoms of carbon and
hydrogen plus one or more atoms of fluorine,
bromine, chlorine, or iodine which may be
Trichlorotrifluoroethane should always be
treated as a toxic solvent. Exposure to it can cause
headache, rapid heartbeat, light-headedness, and
tingling of fingers or toes. Any of these symptoms
is a warning to leave the area immediately. In
higher concentrations the solvent has an anesthetic
effect (causing uncoordination and stumbling); it
can effect the heartbeat (causing irregular beats
or even stoppage) and can cause tremors, convul-
sions, and DEATH. Refrigerant gases such as
Freon 12 and 22 have properties similar to the