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Isolation of the Refrigerant Charge
on the Low side of the System
By closing the suction-line service valve, refrigerant
charge can be isolated in the evaporator for maintenance
Sound power levels
on the compressor.
Returning the unit to running conditions:
Discharge
1. Open all the valves.
Measurement conditions:
2. Manually Open EXV for 15 minutes to allow the
Measurements taken in a room adjacent to the room containing the FWD, at the outlet of the rectangular duct (1.5 m
refrigerant drain to the evaporator by gravity.
long) fixed to its discharge opening.
Low side Charge-isolation Procedure
Fan
Unit
speed
After normal shutdown, most of the charge resides in the
1
evaporator. Running cold water through the evaporator may
FWD 08
2
also drive much of the refrigerant to the evaporator.
3
1
FWD 10
2
1.
Make sure the circuit is off.
3
2.
Close the suction-line isolation valve.
1
3.
Close the liquid line service valve.
FWD 12
2
4.
Close the liquid line service valve
3
5.
Manually open the EXV
1
FWD 14
2
6.
Use a liquid pump or vacuum pump to move refrigerant
3
from the condenser to the evaporator. The liquid pump
1
will only be effective if there is a lot of charge in the
FWD 20
2
condenser. It may be connected to the condenser drain
3
port on the liquid-line isolation valve.
Intake
Note: If a pump is to be used, connect it before closing
this valve. This port is only isolated when the valve is back
Measurement conditions:
seated. If a vacuum pump is used, then connect it to the
Measurements taken at the horizontal air intake.
discharge-line service valve.
A vacuum pump will be required for part of the procedure.
Fan
Unit
speed
The evaporator is large enough to hold all the charge, for any
1
FWD 08
2
unit, below the centerline of the shell. Therefore, no special
3
precautions are required to restart the unit after isolating the
1
charge in the evaporator.
FWD 10
2
3
1
FWD 12
2
3
1
FWD 14
2
3
1
FWD 20
2
3
CTV-SVX009D-GB
UNT-PRC002-GB
Power level in dB(A), per Hz frequency band
125
250
500
55
50
42
57
54
47
58
57
50
57
51
45
58
54
48
60
58
50
57
51
45
58
54
48
60
58
50
56
62
50
61
66
55
63
69
58
57
63
51
61
66
55
63
69
58
Power level in dB(A), per Hz frequency band
125
250
500
56
55
55
63
62
60
66
65
63
62
58
55
66
63
60
70
67
63
62
58
55
66
63
60
70
67
63
66
65
65
73
72
69
78
76
73
68
72
64
76
76
68
78
79
71
Periodic Maintenance
Refrigerant Filter Replacement –
Changing Procedures
A dirty filter is indicated by a temperature gradient
across the filter, corresponding to a pressure drop. If the
temperature downstream of the filter is 4,4°C lower than
the upstream temperature, the filter should be replaced.
A temperature drop can also indicate that the unit is
undercharged.
GVAF has economizer and compressor cooling system,
besides to close EXV and liquid shutoff valve, any flow to
liquid cooling and economizer needs to be cutoff.
Lubrication System
1000
2000
37
37
No oil is needed in an oil free centrifugal compressor
40
30
and the use of oil is prohibited as it can damage internal
42
32
compressor parts.
42
34
45
38
Vacuum
48
40
42
34
Ensure gas removal by vacuum the 3 main areas of the unit
45
38
48
40
(suction side, discharge side and economizer side (between
48
39
TEXV and economizer shut off valve)).
53
47
56
50
49
40
53
47
56
50
1000
2000
53
46
60
53
62
56
58
51
62
56
65
59
58
51
62
56
65
59
65
57
71
64
75
69
64
56
71
65
74
69
Overall power
4000
8000
dB(A)
31
30
46
38
40
50
40
43
53
33
28
48
39
35
51
42
39
54
33
28
48
39
35
51
42
39
54
38
36
56
46
45
60
50
49
63
39
37
57
46
45
60
50
49
63
Overall power
4000
8000
dB(A)
45
42
57
53
53
64
55
57
67
48
44
61
55
52
66
59
57
69
48
44
61
55
52
66
59
57
69
50
46
68
59
57
74
64
63
78
52
50
69
61
61
75
66
66
78
11
51
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