Example Suction Line Sizing - Trane RTAA-70 Installation & Maintenance Manual

RTAA-SVX01A-EN
Installation — Remote Evaporator
column find the outside diameter that corresponds to the equivalent
length computed in step #6.
8. Use Table 3 and the diameter found in step #7 to determine the equiva-
lent lengths of each fitting.
9. Sum the following: equivalent lengths of the fittings from step #8, the
actual length of the horizontal or downflow suction line, and the equiva-
lent length of the upflow line found in step # 4. This is the new estimate
of the equivalent length of the entire suction line.
10. With the new length found in step #9, go back to
new diameter for the circuit you are sizing.
11. Repeat steps #8-10 with the new diameter found in step # 10.
12. The diameter found in step #11 is the horizontal or downflow suction line
diameter.
13. The diameter found in step #2 is the diameter of the upflow suction line
and any fittings in the upflow line.
NOTE: The diameters of the upflow, and horizontal or downflow portions of
the suction line may differ depending on the application.

Example Suction Line Sizing

For this example, refer to
a 100 ton chiller.
1. From 23, the actual length of upflow, and horizontal or downflow is:
upflow (20 + 5) = 25 feet
horizontal or downflow (75+8) = 83 ft.
2. Table 5 for a 50 ton circuit shows: Upflow suction line outside diameter
= 2-5/8 inches
3. According to Figure
diameter of 2-5/8 inches:
6 elbows x 3.4 feet = 20.4 feet
4. Final equivalent length of upflow suction line:
20.4 + 25 = 45.4 feet
5. There are no fittings in the horizontal portion. Therefore, the final
equivalent line length is:
45.4 + 83 = 128.4 feet
6. From Table 6, for a 50 ton circuit, and 125 equivalent feet
(nearest to 128.4):
Horizontal or downflow suction line
diameter = 2-5/8 inches
NOTE: In this example, the horizontal line is pitched downward in the
direction of flow.
Table 3, 5, 6, and 23, and assume a 50 ton circuit on
23, there are 6 long radius ELLs. From Table 2b for a
Table 6 and find the
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