IM 738-2
43
Mechanical Installation:
RFS/RCS Permanent Split Systems
such that only liquid leaves the tank but vapor enters the
compressor.
This is especially true with R-407C because the charge must
be drawn from the liquid portion of the tank.
Refrigerant Charge
Each unit is designed for use with R-22 or R-407C.The total
charge per circuit is the sum of the following four values:
•
Condenser section charge, see Table 13 on page 40.
•
Evaporator coil charge, see Table 13 on page 40.
•
Charge for length of unit piping to the evaporator coil, see
Table 13 on page 40.
•
Charge for length of interconnecting piping between the
RCS and RFS units, installed by field, see Table 17 on
page 41.
The exact charge for a one piece RPS/RDT is on the unit
nameplate.
Note:
The total operating charge per circuit should not exceed
the pumpdown capacity per circuit, shown in Tables 13
to 17 on pages 40 to 41.
Subcooling
When field charging the unit, use the following to properly
charge the unit:
•
All compressors on each circuit operating at full capacity.
•
Allowable subcooling ranges are between 13°F to 20°F.
•
Be sure to measure pressure and temperature at the same
location when finding/calculating subcooling. Compare the
actual temperature and pressures to the saturated liquid
temperature. R-407C example: A pressure of 250 psi is
measured at the condenser outlet. From the R-407C chart,
250 psig is approximately 108°F saturated liquid
temperature. If the actual refrigerant temperature is 98°F, the
liquid is subcooled 10°F.
•
Ambient temperature must be between 60°F and 105°F.
•
Hot Gas Bypass NOT operating (only if unit is supplied with
option)
•
SpeedTrol motors operating at 100% (only if unit is supplied
with option)
If any one of the above items is not followed, subcooling
readings will not be accurate and the potential exists for over or
undercharging of the refrigerant circuit.
Refrigeration Service Valves
The unit is shipped with all refrigeration service valves closed.
RDT, RPS and RCS units have the following:
Sizes 15 to 105—
One discharge valve is provided per
refrigerant circuit, located between the compressors and
condenser.
Sizes 115 to 135
—One service valve is provided on the
discharge and suction of each compressor.
All Units—
One liquid valve is provided per refrigeration
circuit, located at end of condensing section opposite
condenser control box.
RFS units do not ship with service valves installed. Before
attempting to start the compressors, all refrigeration service
valves should be fully opened and backseated.
CAUTION
Units purchased for R-22 operation must be charged only
with R-22. Units purchased for R-407C operation must be
charged only with R-407C.
Field mixing or changing of refrigerants can compromise
performance and damage equipment.
Table 19: Acceptable refrigerant oils
R-22 (mineral oils)
Note: Do not use mixtures of
mineral oils and POE oils with R-22.
R-407C (polyolester [POE] oils)
Note: Do not use mineral oils with
R-407C
.
Sunisco 3GS
Copeland ULtra 22 CC
Texaco WF32
Mobil EAL™ Arctic 22 CC
Calumet R015
ICI EMKARATE RL™ 32CL
Table 20: Weight of refrigerant R-22 in copper lines
(pounds per 100 feet of Type L tubing)
O.D.
line
size
Vol. per
100 ft.
in cubic
feet
Weight of refrigerant, lbs./100 feet
Liquid @
100°F
Hot gas
@ 120°F
cond.
Suction gas (superheat to
85°F)
30°F
40°F
3/8"
0.054
3.84
0.202
0.052
0.077
1/2"
0.100
7.12
0.374
0.098
0.143
5/8"
0.162
7.12
0.605
0.158
0.232
7/8"
0.336
24.00
1.260
0.323
0.480
1 1/8"
0.573
40.80
2.140
0.550
0.820
1 3/8"
0.872
62.10
3.260
0.839
1.250
1 5/8"
1.237
88.00
4.620
1.190
1.770
2 1/8"
2.147
153.00
8.040
2.060
3.060
2 5/8"
3.312
236.00
12,400
3.180
4.720
3 1/8"
4.728
336.00
17.700
4.550
6.750
3 5/8"
6.398
456.00
24.000
6.150
9.140
4 1/8"
8.313
592.00
31.100
8.000
11.190
