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General Refrigerant Piping System Information
Due to our policy of continuous product innovation, some specifications may change without notification.
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GENERAL REFRIGERANT PIPING SYSTEM
Refrigerant Safety Standards
ASHRAE Standards 15-2010 and 34-2010 address refrigerant safety and the maximum allowable concentration of refrigerant in an occupied
space. Refrigerant will dissipate into the atmosphere, but a certain volume of air is required to safely dissipate the refrigerant. For R410A
refrigerant, the maximum allowable concentration of refrigerant is 26 lbs./1,000 cubic feet (Addendum L modified the RCL to 26) of occupied
spaces. Buildings with 24-hour occupancy allow half of that concentration.
If a VRF system develops a refrigerant leak, the entire refrigerant charge of the system will dump into the area where the leak occurs. To
meet ASHRAE Standards 15 and 34, the smallest room volume on the system must be calculated and compared to the maximum allowable
concentration. If the concentration level is higher than allowed, the following are some design suggestions to eliminate the problem:
• Split dual-frame and triple-frame systems into single-frame systems that have lower refrigerant charges.
• Add transfer grilles in the ceiling or walls of the smaller rooms to increase the volume of the room.
• Remove the smallest space from the system and serve it with a smaller mini-split system.
Selecting Field-Supplied Copper Piping For DOAS Units
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LG prefers the use of hard drawn copper in pipe segments connecting a Dedicated Outdoor Air System (DOAS) product and a heat recovery
outdoor unit.
Table 5: ACR Rated Copper Tubing Material.
Table 6: ACR Rated Piping Wall Thicknesses.
Type
Seamless Phosphorous Deoxidized
Class
UNS C12200 DHP
Straight Lengths
H58 Temper
Coils
O60 Temper
OD (in)
1/4
3/8
1/2
5/8
3/4
7/8
1-1/8
1-3/8
1-5/8
Material
Rigid or Soft ACR Rated for R410A
Rigid or Soft ACR Rated for R410A
Min. Bend Radius (in)
0.563
0.9375
1.5
2.25
3.0
3.0
3.5
4.0
4.5
Min. Wall Thickness (in)
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.04
0.050
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Nominal Pipe
Outside
Diameter (in)
Actual Outside
Diameter (in)
Tempered (Hard Drawn)
Annealed (Soft)
Nominal Wall
Thickness (in)
Weight (lb/ft)
Cubic ft per
Linear ft
Nominal Wall
Thickness (in)
Weight (lb/ft)
Cubic ft per
Linear ft
1/4
0.250
--
--
--
0.030
0.081
0.00020
3/8
0.375
0.030
0.126
0.00054
0.032
0.134
0.00053
1/2
0.500
0.035
0.198
0.00101
0.032
0.182
0.00103
5/8
0.625
0.040
0.285
0.00162
0.035
0.251
0.00168
3/4
0.750
0.042
0.362
0.00242
0.042
0.362
0.00242
7/8
0.875
0.045
0.455
0.00336
0.045
0.455
0.00336
1-1/8
1.125
0.050
0.655
0.00573
0.050
0.655
0.00573
1
All dimensions provided are in accordance with ASTM B280 – Standard.
2
Design pressure = 551 psig.
3
The Copper Tube Handbook, 2010, Copper Development Association Inc., 260 Madison Avenue, New York, NY 10016.
Table 7: ACR Copper Tubing Dimensions and Physical Characteristics
1-3
• Commercially available piping often contains dust and other materials. Always blow it clean with a dry nitrogen.
• Prevent dust, water or other contaminants from entering the piping during installation.
Refrigerant Safety / Selecting Piping
