Refrigeration; Leak Testing; Evacuation - Hussmann HGL-1BS Installation And Service Instructions Manual

securely taped to one of the return bends two
thirds of the way through the evaporator cir-
cuit. Some "hunting" of the expansion valve is
normal. The valve should be adjusted so that
during the hunting the greatest difference be-
tween the two probes is 3°F. Make adjustments
of no more than one half turn of the valve stem
at a time and wait for at least fifteen minutes
before rechecking probe temperature and mak-
ing further adjustments. Replace and tighten
cover of the valve stem.
Refrigeration –
As stated previously, these cases are self-
contained systems featuring semi-hermetic
compressors and thermostatic expansion valves.
The condensers are of a fin-and tube construc-
tion and should be periodically cleaned to main-
tain efficient operation.
If it should become necessary to leak test
the system; please adhere to the following no-
tice:
BECAUSE OF CFC ATMOSPHERIC CON-
SIDERATIONS BEING TAKEN TODAY, WE
ASK THAT LEAK TESTING BE DONE
WITH REFRIGERANT 22 MIXED WITH NI-
TROGEN. IF THE CONDENSING UNIT
NAMEPLATE DESIGNATES A REFRIGER-
ANT OTHER THAN R-22 REMOVE ALL R-
22 FROM THE IMMEDIATE AREA TO
AVOID CONFUSION AFTER LEAK TEST-
ING AND EVACUATING THE UNIT. RE-
CHARGE THE UNIT WITH PROPER RE-
FRIGERANT.
Leak Testing –
CAUTION
The test gas cylinder must be equipped
with a pressure gauge and regulator so that
system test pressures do not exceed maximum
allowable limits. Do not ever use anything
other than an R-22/Nitrogen mixture for leak
testing.
Attach a refrigerant test gas cylinder
to your service manifold and connect the
manifold to the charging port on the liquid
line valve. Charge an R-22/Nitrogen mixture
into the system, raising the pressure to the
unit's nameplate for the low side and high
side pressures. Using an electronic detector,
carefully check the entire system for leaks.
Take special care to inspect all brazed and
flare connections.
Evacuation –
After the system is proven leak tight,
thoroughly evacuate the system according to
the following procedure:
Discharge the refrigerant-nitrogen mix-
ture, allowing it to blow from the system
as rapidly as possible, into an empty cylin-
der. Be sure that all service valves and
solenoid valves are open to allow all of the
mixture to be discharged.
Connect a deep-drain vacuum pump to
both the high and low side of the system.
Pull a vacuum on the system to at least
1500 microns.
Break the vacuum by adding refrigerant
into the system until the pressure is above
0 psig. Always charge the refrigerant line
into the system through a new drier in the
charging manifold line. A 16 cubic inch
drier is sufficient for this purpose.
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