6--12
T-334
NOTE
If the condenser cooling water is not being used
as drinking water or is not re-circulated in a
closed or tower system, neutralizing is not nec-
essary.
11. Put the unit back in service and operate under nor-
mal load. Check the head pressure. If normal, a thor-
ough de-scaling has been achieved.
3’ to 4’
1
2
3
4
5
1. Fill condenser with
cleaning solution. Do
not add solution more
rapidly than vent can
exhaust gases caused
by chemical action.
2. Approximately 5’
3. Condenser
4. Vent pipe
5. 1” pipe
Figure 6--10 Water-Cooled Condenser Cleaning -
Gravity Circulation
What You Can Do For Further Help:
Contact the Engineering and Service Department of the
OAKITE PRODUCTS CO., 19 Rector Street, New York,
NY 10006 U.S.A. for the name and address of the
service representative in your area.
6.11 FILTER DRIER
On units equipped with a water-cooled condenser, if the
sight glass appears to be flashing or bubbles are
constantly moving through the sight glass when the
suction modulation valve is fully open, the unit may have
a low refrigerant charge or the filter drier could be
partially plugged.
a. To Check Filter Drier
1. Test for a restricted or plugged filter drier by feeling
the liquid line inlet and outlet connections of the drier
cartridge. If the outlet side feels cooler than the inlet
side, then the filter drier should be changed.
2. Check the moisture-liquid indicator if the indicator
shows a high level of moisture, the filter drier should
be replaced.
b. To Replace Filter Drier
1. Pump down the unit (refer to paragraph 6.3.2). Eva-
cuate if unit is not equipped with service valves (Re-
fer to paragraph 6.4.4). Then replace filter drier.
2. Evacuate the low side in accordance with
paragraph 6.3.4.
3. After unit is in operation, inspect for moisture in sys-
tem and check charge.
6.12 EXPANSION VALVES
Two expansion valves are used: the evaporator
expansion valve (item 8, Figure 2--2), and the
economizer expansion valve (item 19, Figure 2--4). The
expansion valves are automatic devices which maintain
constant superheat of the refrigerant gas leaving at the
point of bulb attachment regardless of suction pressure.
The valve functions are:
1. Automatic control of the refrigerant flow to match the
load.
2. Prevention of liquid refrigerant entering the com-
pressor.
Unless the valve is defective, it seldom requires
maintenance other than periodic inspection to ensure
that the thermal bulb is tightly secured to the suction line
and wrapped with insulating compound. (See
Figure 6--11.)
2
3
1
4
5
1. Suction Line
2. Thumbscrew
3. TXV Bulb Clamp
4. TXV Bulb
5. Foam Insulation
Figure 6--11 Thermostatic Expansion Valve Bulb
6.12.1 Checking Superheat
NOTE
Proper superheat measurement should be
completed at -18C (0F) container box tempera-
ture where possible.
a. Open the upper right (EFM#1) access panel (see
Figure 2--1) to expose the Expansion valve.
b. Attach a temperature sensor near the expansion
valve bulb and insulate. Make sure the suction line is
clean and that firm contact is made with the sensor.
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