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3
AG 31-011 • REFRIGERANT PIPING DESIGN
Introduction
Audience
This Application Guide was created for design engineers and
service technicians to demonstrate how to size refrigerant
piping.
Using This Guide
This Guide covers R-22, R-407C, R-410A, and R-134a used
in commercial air conditioning systems. It does not apply to
industrial refrigeration and/or Variable RefrigerantVolume
(VRV) systems. Illustrations and figures are not to scale.
Examples showing how to perform an analysis appear under
shaded headlines as seen below.
How to Determine Equivalent Length
Calculate the equivalent length of the liquid line for the
following condensing unit with DX air-handling unit.
The liquid line is composed of the following elements:
• 30 ft (9.14 m) of 1-3/8 inch (35 mm) piping
•
4 long radius elbows
•
1 filter-drier
• 1 sight glass
•
1 globe type isolating valve
To determine the equivalent length for the refrigerant
Item
Quantity
Dimension, ft (m)
Total, ft (m)
Long radius elbow
4
2.3 (0.7 m)
9.2 (2.8 m)
Filter-drier
1
35 (10.7 m)
35 (10.7 m)
Sight glass
1
2.5 (0.76 m)
2.5 (0.76 m)
Globe valve
1
38 (11.6 m)
38 (11.6 m)
Piping
1
30 (9.1 m)
30 (9.1 m)
Total
117.7 (34.96 m)