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Interconnecting Tubing (cont�)
Interconnecting Tubing and
Fitting Losses
Refrigerant tubing is measured in terms of actual
length and equivalent length� Actual length is used
for refrigerant charge applications� Equivalent
length takes into account pressure losses from
90° Short
Line Size
Radius
(in)
Elbow
3/8
1.3
1/2
1.4
5/8
1.5
3/4
1.9
7/8
2.3
1-1/8
2.7
Liquid Line Selection
The purpose of the liquid line is to transport warm
sub-cooled liquid refrigerant from the outdoor unit
to the indoor unit� It is important not to allow the
refrigerant to flash any superheated vapor prior
to the expansion device of the indoor coil� The
flashing of refrigerant can occur for the following
reasons:
• Low refrigerant charge
• Improperly selected liquid line size
• Absorption of heat prior to expansion device
• Excessive vertical rise between the condenser
and evaporator
Table 2 lists the equivalent length per 25' of liquid
line at various diameters up to 300'� The total pres-
tubing length, fittings, vertical separation, acces-
sories, and filter dryers. The table below references
different commonly used equivalent lengths.
Table 1
Equivalent Length for Fi ngs ( )
90° Long
Radius
45°
Elbow
Elbow
0.8
0.3
0.9
0.4
1
0.5
1.3
0.6
1.5
0.7
1.8
0.9
sure drop allowed for the liquid line is 50 PSI� The
procedure for selecting the proper liquid line is as
follows:
• Measure the total amount of vertical rise
• Measure the total amount of liquid line needed
• Add all of the equivalent lengths associated with
• Add the total length and fitting pressure drop.
• Round-down the total equivalent length to the
• Reference Table 2 to verify the rounded-down
Figure 1
INSTALLATION
Solenoid
Check
Valve
Valve
6
4
9
5
12
6
14
7
15
8
22
12
any fittings or accessories using the table above.
This will equal your total equivalent length�
closest value in Table 2�
value of the calculated equivalent length is com-
patible with the required vertical rise and diam-
eter of liquid line�
Note: Eleva on is defined as the
highest point of the line set to the
lowest
Site
Filter
Glass
Dryer
0.4
6
0.6
6
0.8
6
0.9
6
1
6
1.5
6
13
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