Preparing System For Charging - Trane TR-SCS Series Installation, Operation And Maintenance Manual

Installation
Table 6. TR-SCS-MC condenser refrigerant charge weights (lb)
R407C Charge
TR-SCS Model
Number
-20°F Ambient &
015-S
018-S
031-S
031-D*
035-S
035-D*
056-S
056-D*
071-S
071-D*
111-S
111-D*
128-D*
142-D*
223-D*
264-D*
334-D*
Note: *Dual refrigeration circuits.
Table 7. Weight of refrigerant (lb/100 ft of type L tubing)
Line Size
Liquid Line 105°F
O.D.
R407C
1/2 6.51
5/8 10.46
7/8 21.73
1 1/8 37.04
1 3/8 56.43
1 5/8 79.87
2 1/8 175.32
Example: Estimate the amount of refrigerant required for
a system using R407C refrigerant consisting of a 5 ton A/
C unit connected with a 1/2-inch x 30 foot liquid line and 
7/8-inch x 30 foot discharge line to a TR-SCS-060-SAA 
-30 °F condenser with flooded head pressure control and
receiver.
A/C Unit = 5.2 lbs.
+ Condenser w/Receiver = 12.2 lbs.
+ ½ Liquid Line 30 x 6.51/100 = 1.953 lbs.
+7/8 inch Discharge Line 30 x 2.91/100 = 0.873 lbs.
Estimated Refrigerant Charge = 20.226 lbs.
Round off to the nearest lb> = 20 lbs.
18
R407C Charge
(Condenser with
Receiver)
-30°F Ambient
Higher
0.8
0.9
1.3
1.6
2.0
2.6
2.0
2.6
3.8
4.8
3.8
4.8
5.8
7.6
7.6
10.4
10.4
Discharge Line 140°F
Condensing
R410A R407C R410A
5.88 0.87 1.27
9.44 1.40 2.03
19.62 2.91 4.22
33.44 4.95 7.20
50.95 7.55 10.97
72.11 10.68 15.53
158.29 23.44 34.09
R410A Charge
-20°F Ambient & Higher
4.4
4.5
6.9
8.8
11.8
13.8
11.8
13.8
19.1
24.4
19.1
24.4
36.4
38.2
38.2
41.0 10.8
41.0 10.8

Preparing System for Charging

1. With all the system piping connections made, perform
a dry nitrogen leak detection test on the system. Using
dry nitrogen only, pressurize the system to 150 psig.
Ensure all service and solenoid valves are energized
open and that no part of the system is isolated from the
pressurized nitrogen (liquid, suction or discharge lines
and reheat coil).
2. Since there is no refrigerant in the system to detect at
this point, leaks may be detected by observing if there
has been a change in the standing pressure after 12
hours. A significant drop in pressure indicates a leak in
the system that needs to be repaired. After the system
is determined to be free of leaks, you may evacuate the
system.
Compressor Damage!
A proper vacuum must be drawn on the refrigerant
system to remove moisture prior to charging. If this is
not done the refrigerant charge will combine with
moisture in the pipes to form an acid that will
eventually lead to compressor failure. A triple
evacuation procedure with dry nitrogen is
recommended especially for systems with newly
installed refrigerant piping.
Note: A vacuum pump should be used that can evacuate
the entire volume of the A/C system, including
R410A Charge
(Condenser with
Receiver)
-30°F Ambient
0.8
1.0
1.3
1.6
2.1
2.6
2.1
2.6
3.9
4.8
3.9
4.8
6.0
7.8
7.8
NOTICE
4.0
4.2
6.4
8.0
11.0
12.8
11.0
12.8
17.8
22.6
17.8
22.6
33.8
35.6
35.6
38.6
38.6
SS-SVX006C-EN