RWF ROTARY SCREW COMPRESSOR UNITS
MAINTENANCE
S70-600 IOM (OCT04)
Page 23
STRAINER - LIQUID INJECTION
To clean the liquid injection strainer the unit must be shut
down. The procedure is as follows:
1.
Push
[STOP]
key on microprocessor panel to shut down
unit, then open disconnect switches for compressor and oil
pump motor starters.
2.
Close liquid supply service valve located before liquid
solenoid.
Excessive pressure from ex-
panding refrigerant trapped be-
tween stop valve and solenoid
may cause gasket and o-ring failure and uncontrolled
refrigerant release.
3.
Close service valve located between the compressor
and the liquid injection thermovalve.
4.
Carefully loosen capscrews securing the strainer cover
to the strainer. Allow pressure to relieve slowly.
5.
When all entrapped refrigerant has been relieved, care-
fully remove loosened capscrews (as liquid refriger ant is
sometimes caught in the strainer), strainer cover and strainer
basket.
6.
Wash the strainer basket and cover in solvent and blow
clean with air.
7.
Reassemble strainer.
8.
Open service valve between compressor and liquid
injection thermovalve and check for leakage.
9.
Screw out manual solenoid valve stem.
10.
Carefully open liquid supply service valve.
11.
Leak test.
12.
Close disconnect switches for compressor and oil pump
motor starters.
13.
Start unit.
COALESCER FILTER ELEMENT(S)
When changing the coalescer filter element(s) it is recom-
mended that the oil be changed, cartridge(s) in oil filters
OF-1 and OF-2 if applicable be changed and the following
applicable strainer elements be removed and cleaned.
Use of filter elements other than
Frick may cause warranty claim
may to be denied.
1.
Refer to
CHANGING OIL,
Steps 1 through 8.
2.
Loosen manway cover retainer bolts, remove retainers,
manway cover and cover gasket. Discard cover gasket.
3.
Remove and retain nut securing coalescer filter retainer.
4.
Remove retainer, coalescer filter element and 2 O-rings.
Discard filter elements.
5.
Install new coalescer filter element(s).
Seat element in center of locating
tabs on separator bulk head.
6.
Replace coalescer filter retainer and nut. Torque nut to 21
ft-lb.
DO NOT OVERTIGHTEN NUT.
7.
Install new manway gasket and replace manway cover.
8.
Tighten manway bolts.
NOTE: RE TIGHTEN AFTER THE
COM PRESSOR UNIT IS REPRESSURIZED, SINCE MAN-
WAY BOLTS WILL LOOSEN.
9.
Refer to
CHANGING OIL,
Steps 9 through 14.
CHANGING OIL
DO NOT MIX OILS of different
brands, manufacturers, or types.
Mixing of oils may cause excessive
oil foaming, nuisance oil level cutouts, oil pressure loss,
gas or oil leakage and catastrophic compressor failure.
Use of filter elements other than
Frick may cause warranty claim
may to be denied.
Shut down the unit when changing oil. At the same time all oil
filter cartridges must be changed and all oil strainer elements
removed and cleaned. The procedure is as follows:
1.
Press the
[STOP]
key on the microprocessor panel
to stop the compressor unit.
2.
Open the disconnect switch for the compressor
motor starter.
3.
Close the suction and discharge service valves; also
close the liquid-injection and economizer service valves, if
applicable.
4.
SLOWLY
vent separator to low-side system pressure
using the bypass line on the suction trap.
NOTE: Recover
or transfer all refrigerant vapor, in accordance with local
ordinances, before opening to atmosphere. The separator
MUST be equalized to atmospheric pressure.
Oil entrained refrigerant may va-
porize, causing a separator pres-
sure increase. Repeat venting and
recovery procedure, if necessary.
5.
Open the drain valve(s) located on the underside of the
separator and drain the oil.
6.
Drain the oil filter(s) OF-1 and, if ap plicable, the oil
coolers and filter OF-2.
7.
Remove the old filter cartridges, then install new
ones (as previously described in the section
OIL FILTER
(OF-1) MAIN SINGLE/DUAL
).
8.
Remove, clean, and reinstall strainer elements in the
strainers.
9.
Evacuate unit to 29.88" Hg (1000 microns) vacuum.
10.
Open the suction service valve and pressurize the unit
to system suction pressure. Close the suction valve and leak
test.
11.
Add oil by attaching a suitable pressure-type hose to
the oil-charging valve located on top of the separator. Using
a pressure-type oil pump and recommended Frick oil, open
the charging valve and fill the separator until the oil level is
midway in the top sight glass.
NOTE: Fill slowly because
oil will fill up in the separator faster than it shows in the