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724-746-5500 | blackbox.com
724-746-5500 | blackbox.com
Page 31
Chapter 2: Installation
2.8.1.2 Refrigerant Pipe Sizing
Refrigerant lines for split systems must be sized according to the piping distance between the evaporator and the condenser. Each
valve, fitting, and bend in the refrigerant line must be considered in this calculation. Pipe sizes are given for “equivalent feet,” not
linear feet. Do not confuse the terminologies. For example, a
7
⁄8" standard 90° elbow has an equivalent length of 1.5 feet; a
7
⁄8"
branch tee has an equivalent length of 3.5 feet. These corrections must be accounted for when sizing your piping.
NOTE: Refrigerant piping between the Cold Row unit and the remote condenser must not exceed 150 feet (total equivalent
length). The maximum level drop from the Cold Row unit to the condenser must not exceed 20 feet.
NOTE: Consult ASHRAE standards and refer to the Copeland applications data guide for more detailed information regarding
refrigerant line traps and line sizing.
Refer to the following table for standard equivalent lengths, in feet, of straight pipe.
Table 2-5. Equivalent length of straight pipe.
OD (in.) Line Size Globe Valve Angle Valve 90° Elbow 45° Elbow
Tee Line Tee Branch
1
⁄2 9.0 5.0 0.9 0.4 0.6 2.0
5
⁄8 12 6.0 1.0 0.5 0.8 2.5
7
⁄8 15 8.0 1.5 0.7 1.0 3.5
1
1
⁄8 22 12 1.8 0.9 1.5 4.5
1
3
⁄8 28 15 2.4 1.2 1.8 6.0
Oil traps must be included every 20 feet in the vertical risers, and the refrigerant lines must be sloped
1
⁄4 inch for every 10 feet in
the horizontal lines to ensure proper oil return to the compressor. An inverted trap is required on the discharge line of the remote
condenser to help prevent oil and liquid from flooding back to the compressor.
2.8.2 Remote Air-Cooled Condensers
Refer to the Recommended Discharge Line and Liquid Line sizing tables below. Systems using air-cooled condensers must not
have a refrigerant line pressure drop over 14 psig across the condenser and the interconnecting piping to the condenser.
NOTE: Ensure proper condenser selection to maintain reasonable sub-cooling temperatures.
Table 2-6. Recommended discharge line sizes.
Model Number
*Equivalent Length Ft.
50 ft.. or less 100 ft. or less 150 ft. or less
CRDX-A-FS-12KW
5
⁄8
5
⁄8
5
⁄8
CRDX-A-FS-24KW
7
⁄8
7
⁄8
7
⁄8
*Equivalent feet accounts for the linear pipe length as well as equivalent length of valves, elbows, and tees as shown in the
previous table.
Table 2-7. Recommended liquid line sizes.
Model Number
*Equivalent Length Ft.
50 ft.. or less 100 ft. or less 150 ft. or less
CRDX-A-FS-12KW
1
⁄2
1
⁄2
1
⁄2
CRDX-A-FS-24KW
5
⁄8
5
⁄8
5
⁄8