RXB PLUS ROTARY SCREW COMPRESSOR UNITS
INSTALLATION
070.101-IOM (JAN 13)
Page 10
LIQUID INJECTION OIL COOLING
The.liquid.injection.system.provided.on.the.unit.is.self-con-
tained.but.requires.the.connection.of.the.liquid.line.sized.as.
shown.in.the.table.and.careful.insertion.of.the.expansion.valve.
bulb.into.the.thermowell.provided.in.the.separator..High.pres-
sure.gas.is.connected.through.the.regulator.to.the.external.
port.on.the.liquid.injection.valve.to.control.oil.temperature..
Refer.to.the.liquid.injection.piping.diagram.
NOTE: For booster applications, the high pressure gas
connection must be taken from a high side source (high-
stage compressor discharge). This should be a minimum
3/8" line connected into the solenoid valve provided. This
gas is required by the expansion valve external port to
control oil temperature.
High-stage.compressor.units.may.be.supplied.with.single-
port.(low.Vi).or.dual-port.(low.Vi.and.high.Vi),.liquid.injection.
oil.cooling..Single.port.will.be.furnished.for.low.compression.
ratio.operation.and.dual.port.for.high.compression.ratio.opera-
tion..Booster.compressor.units.use.single-port,.liquid.injection.
oil.cooling.due.to.the.typically.lower.compression.ratios.
The.control.system.on.high-stage.units.with.dual-port,.liquid.
injection.oil.cooling.switches.the.liquid.refrigerant.supply.to
the.high.port.when.the.compressor.is.operating.at.higher.
compression.ratios.(3.5.Vi.and.above).for.best.efficiency.
The. following. table. gives. the. condensing. temperature(s).
with. the. corresponding. maximum. evaporator. temperature.
limit.for.liquid.injection.usage.and.the.minimum.evaporator.
temperature.for.a.single-port.application.
TABLE - EVAPORATOR TEMPERATURE with
SINGLE-PORT LIQUID INJECTION
CONDENS-
ING
TEMP
MAXIMUM
EVAPORATOR
TEMPERATURE FOR
LIQUID INJECTION
USAGE
MINI MUM *
EVAP TEMP
FOR
SINGLE PORT
(LOW Vi)
R-717
R-717
75°F
+10°F
-23°F
85°F
+25°F
-17°F
95°F
+35°F
-11°F
105°F
+40°F
-.4°F
*. Dual.Injection.Kit.will.be.shipped.by.Frick.
below.these.temperatures.
Where.low.compres.sion.ratios.(low.condensing.pressures).
are.anticipated,.thermo.syphon.or.water-cooled.oil.cooling.
should. be. used.. It. is.
IMPERA TIVE
. that. an. uninterrupt.ed.
supply. of. high. pres.sure. liquid. refrig.erant. be. provided. to.
the. injection. system. at. all. times..Two. items. of.
EXTREME
IMPORTANCE
.are.the.design.of.the.receiver/liquid.injection.
supply.and.the.size.of.the.liquid.line..It.is.recommended.that.
the. receiver. be. oversized. sufficiently. to. retain. a. 5. minute.
supply.of.refrigerant.for.oil.cooling..The.evaporator.supply.
must. be. secondary. to. this. considera.tion..Two. methods. of.
ac.complishing.this.are.shown.
DUAL DIP TUBE METHOD
The.dual.dip.tube.method.uses.two.dip.tubes.in.the.re.ceiv-
er..The.liquid.injection.tube.is.below.the.evaporator.tube.to.
ensure.continued.oil.cooling.when.the.receiver.level.is.low.
Figure 11 - Dual Dip Tube Liquid Injection
LEVEL CONTROL METHOD
The.level.control.method.utilizes.a.float.level.control.on.the.
receiver. to. close. a. solenoid. valve. feeding. the. evapora.tor.
when. the. liquid. falls. below. that. amount. necessary. for. 5.
minutes.of.liquid.injection.oil.cooling.
Figure 12 - Level Control Liquid Injection
Liquid.line.sizes.and.the.additional.receiver.volume.(quantity.
of. refrigerant. required. for. 5. minutes. of. liquid. injection. oil.
cooling).are.given.in.the.following.table:
REF
RXB
MODEL
LIQ. LINE SIZE*
FLOW
RATE (lb.)
5 MIN
LIQUID
VOLUME
CU.FT.
PIPE
SCH 80
TUBING
OD
HIGH
STAGE
R-717
12
1/2
–
10
.3
15
1/2
–
12.5
.4
19
1/2
–
15
.4
24
1/2
–
20
.6
30
1/2
–
25
.7
39
1/2
–
30
8
50
3/4
–
40
1.1
BOOST-
ER
R-717
12
1/2
–
2
.1
15
1/2
–
2.5
.1
19
1/2
–
3.5
.1
24
1/2
–
4.5
.1
30
1/2
–
5.5
.2
39
1/2
–
6.5
.2
50
1/2
–-
8.5
.3
*
.100.ft..liquid.line...For.longer.runs,.increase.line.size.ac-
cordingly.
WATER-COOLED OIL COOLING (OPTION AL)
The.shell.and.tube-type,.water-cooled.oil.cooler.is.mounted.
on.the.unit.complete.with.all.oil.piping..The.customer.must.
supply.adequate.water.connections.and.install.the.two-way.
water.regulating.valve..It.is.recom.mended.that.(local.codes.
permitting).the.water.regula.tor.be.installed.on.the.water.outlet.
connection..Insert.the.water.regulator.valve.bulb.and.well.in.