4. Close the discharge gage line and open the
discharge line stop valve.
5. Remove all oil from the exterior of the
compressor, and test the compressor joints for
leakage, using the halide leak detector.
CLEANING SUCTION STRAINERS
When putting a new unit into operation, the
suction strainers should be cleaned after a few
hours of operation. Refrigerants have a solvent
action and will loosen any foreign matter in the
system. This foreign matter will eventually reach
the suction strainers and after a few days of opera-
tion, the strainers will need cleaning. Strainers
should be inspected frequently during the first few
weeks of plant operation, and then cleaned as
The suction strainers are located either in the
compressor housing or in the suction piping. The
procedure for cleaning a strainer is as follows:
Pump down the compressor.
Slowly bleed pressure from unit.
Remove the strainer and inspect it for
Clean the strainer screen by dipping it in
an approved solvent and then allow it to
Replace the strainer and evacuate the air
from the compressor.
Test the housing for leaks by wiping up all
oil and then using a halide leak detector.
The compressor discharge line terminates at
the refrigerant condenser. In shipboard R-12
installations, these condensers are usually of the
multipass shell-and-tube type, with water cir-
culating through the tubes. The tubes are ex-
panded into grooved holes in the tube sheet so
as to make an absolutely tight joint between the
shell and the circulating water. Refrigerant vapor
is admitted to the shell, and condenses on the
outer surfaces of the tubes.
Any air or noncondensable gases which may
accidentally enter the refrigeration system is
drawn through the piping and eventually dis-
charged into the condenser with the R-12 gas. The
air or noncondensable gases accumulated in the
condenser are lighter than the refrigerant gas and
rise to the top of the condenser when the plant
is shut down. A purge valve, for purging the
refrigeration system (when necessary), is installed
either at the top of the condenser, or at a high
point in the compressor discharge line.
CLEANING CONDENSER TUBES
In order to clean the condenser tubes
properly, it is necessary first to drain the cooling
water from the condenser and then disconnect the
water connections and remove the condenser
heads. When you remove the condenser heads,
be careful not to damage the gaskets between the
tube sheet and the water side of the condenser
heads. Tubes should be inspected as often as prac-
ticable and be cleaned when necessary, by using
any approved method. Use rubber plugs and an
air or water lance when it is necessary to remove
foreign deposits. Although it is essential that the
tube surfaces be kept clear of particles of foreign
matter, care must be taken not to destroy the thin
protective coating on the inner surfaces of the
tubes. When the tubes become badly corroded,
they should be replaced in order to avoid the
possibility of losing the R-12 charge and admit-
ting salt water into the R-12 system.
Although the large plants are equipped with
water-cooled condensers, the auxiliary units are
commonly provided with air-cooled condensers.
The use of air-cooled condensers eliminates the
necessity for circulating water pumps and piping.
The exterior surface of the tubes and fins on
a condenser should be kept free of dirt and any
matter that might obstruct heat flow and air cir-
culation. Brush the finned surface clean with a
stiff bristle brush as often as necessary. Use low
pressure air to remove dirt in hard to reach places
on the condenser. When installations are exposed
to salt spray and rain through open doors or
hatches, take care to minimize corrosion of the
ENGINEMAN 1 & C