Recommended Procedure for Det
ermining the Proper Refrigerant
Pipe Sizes for Typical Refrigeration and Air Conditioning Systems
To carry out these objectives
you will require the following:
1. This check list.
2. A pressure / temperature
chart for the specified refrigerant.
3. DuPont’s Refriger
ant Piping "Quick Pick" Handbook.
4. The minimum and maximum design load conditi
ons for this specific refrigeration / air conditioning
system.
5. Obtain the satura
ted suction temperature, satu
rated condensing temperature
for this specific system.
6. Determine the maximum allo
wable pressure drops expressed in
psig for this specific refrigerant
at the
stated design conditions.
7. Using the accepted industry standard of plus 50 %,
determine the approxima
te equivalent length by
making a reasonable es
timate of the to
tal equivalent length of
tubing for each piping run.
8. Find the prelimi
nary tubing size for ea
ch selected piping run.
9. Determine the actual
equivalent tube length
of each piping run including its fittings and
ancillary devices.
10. Calculate the allowable pressure drop based on a
maximum of 2 F degrees for suction vapour
lines and 1 F degree for liquid lines.
11. Add the actual tube
length plus the equivalent lengths fo
r all the various fittings and components
for each
individual pipe run