15
Refrigerant Piping
WARNING
All local codes must be observed in the installation of refrigerant piping.
IMPORTANT PIPING NOTE
Appropriate line sizing practices must be used throughout the installation of the refrigeration system. Special
consideration must be taken when the condensing unit is installed above the evaporator.
REFRIGERATION
GRADE COPPER TUBING MUST BE USED FOR PIPING SYSTEMS.
Piping practice and line sizing charts as recommended by A.S.H.R.A.E. or other reputable refrigeration
standards must be followed to ensure minimum pressure drop and correct oil return. An inert gas such as dry
nitrogen should be passed through the piping during welding or brazing operations. This reduces or eliminates
oxidation of the copper and formation of scale inside the piping. For specific piping requirements refer to your
local distributor or sales representative.
Correct line sizing is most critical because of the several factors involved:
(a)
Minimum pressure drop to ensure efficient compressor performance.
(b)
Sufficient gas velocity to maintain proper oil return to the compressor under all load conditions.
(c)
Elimination of conditions on multiple evaporators whereby oil may log in an idle evaporator.
Suction lines should be sized on the basis of a maximum total pressure drop equivalent to a 2
o
F (1.1
o
C) change
in saturated temperature. At 40
o
F (4.4
o
C) suction temperature, this is approximately 3 psig (20.7 kPa) for R-22.
At -20
o
F (-28.9
o
C) suction temperature, this is approximately 1.3 psig (9.0 kPa) for R-404A.
Horizontal liquid lines should be sized on a basis of a maximum pressure drop equivalent to a 2
o
F (1.1
o
C) drop
in the sub-cooling temperature. If the lines must travel up vertically then adequate sub-cooling must be provided
to overcome the vertical liquid head pressures. A head of two feet of liquid refrigerant is approximately
equivalent to 1 psig (6.9 kPa). Liquid line velocities should not exceed 300 fpm (1.52 m/s). This will prevent
possible liquid hammering when the solenoid valve closes.
PSIG
o
F
PSIG
o
F
PSIG
o
F
PSIG
o
F
PSIG
o
F
R-134a
4.9
2.0
7.4
2.9
9.8
4.1
12.3
5.2
14.7
6.3
R-22
4.8
1.6
7.3
2.3
9.7
3.1
12.1
3.8
14.5
4.7
R-404A, R-507
4.1
1.1
6.1
1.6
8.2
2.1
10.2
2.7
12.2
3.3
PSIG
o
F
PSIG
o
F
PSIG
o
F
PSIG
o
F
R-134a
19.7
8.8
24.6
11.0
36.8
17.0
49.1
23.7
R-22
19.4
6.2
24.2
8.0
36.3
12.1
48.4
16.5
R-404A, R-507
16.3
14.1
20.4
5.6
30.6
8.3
40.8
11.8
Based on 110
o
F liquid temperature at bottom of riser.
Refrigerant
Liquid Line Rise in Feet
Liquid Line Rise in Feet
Pressure Loss of Liquid Refrigerant in Liquid Line Risers
(Expressed in Pressure Drop PSIG and Subcooling Loss
o
F)
40'
50'
75'
100'
Refrigerant
30'
10'
15'
20'
25'
Summary of Contents for K40-CU-IM-13
Page 8: ...8 Electrical Wiring Diagram Horizontal Air Flow Condensing Units K Line ...
Page 9: ...9 Electrical Wiring Diagram Horizontal Air Flow Condensing Units K Line ...
Page 10: ...10 Electrical Wiring Diagram Horizontal Air Flow Condensing Units K Line ...
Page 11: ...11 Electrical Wiring Diagram Horizontal Air Flow Condensing Units KE Line ...
Page 12: ...12 Electrical Wiring Diagram Horizontal Air Flow Condensing Units KE Line ...
Page 13: ...13 Electrical Wiring Diagram Horizontal Air Flow Condensing Units KE Line ...
Page 14: ...14 Electrical Wiring Diagram Vertical Air Flow Condensing Units ...
