Head pressure control valve operation ori/ord, Table 1 table 2, Table 3 – ClimaCool IOM AR2 SERIES User Manual
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Head Pressure Control Valve Operation ORI/ORD
EXAMPLE: Our example calls for a compressor equipped with
unloaders . Since the compressor would unload at the low ambients
this must be taken into consideration . This is necessary since as the
compressor unloads, the condenser’s capacity increases and additional
flooding is required . Using the same roof-top unit as in the earlier
example (40°F evaporator and minus 20°F minimum ambient), a
multiplier of .79 is shown in Table-2 . And since we have unloaders
(50%), this .79 is used to enter Table-3 to find a multiplier of .91 . This
final multiplier is applied to the 119 pounds calculated earlier to arrive
at the final extra charge requirement: 119 x .91 = 108 pounds . This is
added to the normal system charge to arrive at a total system charge .
Table 1
Table 2
Percent of Condenser to be
Flooded
High Suction Temp.
A/C Chillers
Evaporating Temperature
o
F
Condenser
Ambient
Temperature
o
F
35
40
45
50
80
0
0
0
0
70
0
0
0
0
60
26
20
10
4
50
45
40
33
28
40
56
52
46
42
30
64
60
55
51
20
69
66
62
59
0
76
73
70
68
-20
80
79
76
73
Table 3
Condenser Flooding
with NO Unloading
Percent of Full
Compressor
Capacity
= 50%
0
5
5
0
3
5
0
1
7
5
5
1
0
6
0
2
3
6
5
2
6
6
0
3
9
6
5
3
2
7
0
4
4
7
5
4
6
7
0
5
9
7
5
5
1
8
0
6
3
8
5
6
6
8
0
7
8
8
5
7
1
9
9
7
*
2
9
0
8
6
9
5
8