Samsung Electronics DVM Series Technical Manual page 216

Equivalent length calculation method
equivalent length = actual pipe length + number of elbows + number of elbows X equivalent length of each elbows
+ number of oil traps X equivalent length of each oil trap
Piping diameter
3/8"
1/2"
5/8"
3/4"
7/8"
1"
1 1/8"
1 1/4"
Examples of equivalent length calculation : When 10 horse power outdoor unit's actual length is 262ft.,
Application of equivalent length
1. When the equivalent length is more than 90% of the actually allowed piping length (more than
207ft. in five/six horse powers, 295ft. in seven/eight/ten horse powers, the gas pipe
diameter of the main piping (piping from the outdoor unit to the first bypass) is expanded a level.
For instance, when the equivalent length of 10 horse power outdoor unit is more than 328ft., the
gas pipe diameter is changed to 1 1/4" from 1 1/8".
2. When the diameter of gas pipes is uplifted one level, the effective equivalent length is
recalculated, and the piping length is calculated based on the effective equivalent length
when looking into the graph to calculate the performance reduction by the long piping.
Effective equivalent length = equivalent length of main piping X 0.5 + equivalent length after the by path
Examples of effective equivalent length calculation : When the actual length of 10 horse power outdoor unit is 262ft.,
Type
Elbow
0.18
0.20
0.25
0.35
0.40
0.45
0.50
0.55
the piping diameter is 1", twelve elbows and two traps are used, the
equivalent length is 262+0.45X12+3.4X2 = 274.2(ft.)
(when the diameter of gas pipe of the main piping is uplifted a level)
piping after bypass 65ft., the diameter of gas pipe
of the main piping is 1", twelve elbows and two oil traps
are used (elbows and oil traps are used only in main piping).
Equivalent length = 262+0.45X12+3.4X2=274.2(ft.)
As the equivalent length is more than 295ft., the
diameter of gas pipe in the main piping is uplifted one level.
Effective equivalent length = (262+0.45X12+3.4X2)X0.5+65=169.7(ft.)
The performance loss due to the long piping is the same with
equivalent length of 169.7ft. when the diameter of gas pipes
of the main piping is not uplifted one level.
43
Oil Trap
1.3
1.5
2.0
2.4
3.0
3.4
3.7
4.0