temperature of the refrigerant recorded in the container indicates that the gas pressure aligns
correctly with the corresponding temperature. See Table 103 or Table 104.
You must only admit refrigerant vapor from the top of the drum or cylinder to the system until
the system pressure is raised above the corresponding saturation pressure at the highest freezing
point of the chiller liquids. This is to prevent the formation of freezing liquid within any of the chiller
tubes when charging an evacuated system. For water with R-134a at 32°F, the saturation pressure is
28 psig. See Table 103. For water with R-513A at 32°F, the pressure is 32 psig. See Table 104.
Before charging, establish the starting weight for the refrigerant cylinder. After the chiller is vapor
charged to the appropriate saturation pressure, it may be necessary to use a refrigerant pump to
draw vapor from the chiller and discharge it to the vapor connection of the refrigerant cylinder.
This process aids in creating a pressure differential for pushing the refrigerant liquid from the
cylinder to the chiller.
While charging, every precaution must be taken to prevent air from entering the system. Make
up a suitable charging connection from new copper tubing or from properly selected flexible
charging hoses to fit between the system charging valve and the fitting on the charging drum. This
connection must be as short as possible but long enough to permit sufficient flexibility for changing
drums. It must also contain a tee fitting with a valve to serve as a connection point to a vacuum
pump to evacuate the charging lines. Evacuate the charging connection each time the lines are
disconnected for changing cylinders or any of the components of the charging process.
The charging line must also contain a sight-glass so that when liquid charging is performed, you
can monitor the charging line to determine when the liquid is no longer being transferred to the
chiller.
The refrigerant charge is specified for each chiller model on the unit data plate or in the Factory
Order Form (FOF) that is provided for every new sale. Charge the chiller based on the amount
specified in the FOF less 10%. For example, for a chiller that requires 1200# of refrigerant, the initial
refrigerant charge is 1080#, 1200 - 120 = 1080. This allows room to trim the charge as outlined in
Checking and trimming the refrigerant charge.
Charge the refrigerant in accordance with the method shown in this section. Record the weight of
the refrigerant charged after the initial charging. Use the next section for trimming the chiller for
optimum operation based on the defined indicators, like discharge superheat, sub-cooling, and
approaches.
Table 103: R-134a pressure to saturated temperature conversion
Pressure
psig (bar)
Dew point
temperature
ºF (ºC)
Pressure
psig (bar)
Dew point
temperature
ºF (ºC)
Pressure
psig (bar)
Dew point
temperature
ºF (ºC)
0.0 (0.0) -14.9 (-26.1) 135.0 (9.31) 105.0 (40.6) 270.0 (18.62) 152.0 (66.7)
5.0 (0.34) -3.0 (-19.4) 140.0 (9.65) 107.2 (41.8) 275.0 (18.96) 153.4 (67.4)
10.0 (0.69) 6.7 (-14.1) 145.0 (10.0) 109.4 (43.0) 280.0 (19.31) 154.7 (68.2)
15.0 (1.03) 14.9 (-9.5) 150.0 (10.34) 111.5 (44.2) 285.0 (19.65) 156.1 (68.9)
20.0 (1.38) 22.2 (-5.4) 155.0 (10.69) 113.6 (45.3) 290.0 (19.99) 157.4 (69.7)
25.0 (1.72) 28.7 (-1.8) 160.0 (11.03) 115.6 (46.4) 295.0 (20.34) 158.7 (70.4)
30.0 (2.07) 34.6 (1.4) 165.0 (11.38) 117.6 (47.6) 300.0 (20.68) 160.0 (71.1)
35.0 (2.41) 40.0 (4.4 ) 170.0 (11.72) 119.6 (48.7) 305.0 (21.03) 161.3 (71.8)
40.0 (2.76) 45.0 (7.2) 175.0 (12.07) 121.5 (49.7) 310.0 (21.37) 162.5 (72.5)
45.0 (3.10) 49.6 (9.8) 180.0 (12.41) 123.3 (50.7) 315.0 (21.72) 163.8 (73.2)
50.0 (3.45) 54.0 ( 12.2) 185.0 (12.76) 125.2 (51.8) 320.0 (22.06) 165.0 (73.9)
55.0 (3.79) 58.1 (14.5) 190.0 (13.10) 126.9 (52.7) 325.0 (22.41) 166.2 (74.6)
60.0 (4.14) 62.0 (16.7) 195.0 (13.44) 128.7 (53.7) 330.0 (22.75) 167.4 (75.2)
65.0 (4.48) 65.7 (18.7) 200.0 (13.79) 130.4 (54.7) 335.0 (23.10) 168.6 (75.9)
70.0 (4.83) 69.2 (20.7) 205.0 (14.13) 132.1 (55.6) 340.0 (23.44) 169.8 (76.6)
75.0 (5.17) 72.6 (22.6) 210.0 (14.48) 133.8 (56.6) 345.0 (23.79) 171.0 (77.2)
80.0 (5.52) 75.9 (24.4) 215.0 (14.82) 135.5 (57.5) 350.0 (24.13) 172.1 (77.8)
YMC
2
Mod B with OptiView Control Center
154
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