User Guide

Design Considerations
22
PG-PF 724998 0320 PureFlow System
Viega PureFlow Pressure Loss
Viega recommends the following velocities for hot and cold PEX water distribution systems:
■ Domestic cold water — 10 fps
■ Domestic hot water — 8 fps
The 󶈶ow velocity through Viega’s PEX 󶈵ttings does not fall under these limitations. The
equivalent length of PEX tube for Viega PureFlow 󶈵ttings is available from Viega to assist in
system sizing where applicable (refer to “Viega PureFlow Press Friction Loss” on page 20 ).
Flow
Rate
GPM
60°F (16°C) Water
Pressure Loss PSI/100 ft of Pipe
⅜ ½ ¾ 1 1¼ 1½ 2
0.5 2.0
0.75 4.1
1.0 7.0 1.6
Pressure Loss <1 psi
1.5 14.9 3.4
2.0 25.4 5.8 1.1
2.5 38.5 8.7 1.6
3.0 53.9 12.2 2.3
3.5 16.2 3.0
4.0 20.8 3.9 1.1
4.5 25.8 4.8 1.4
5.0 31.4 5.9 1.7
6.0 44.0 8.2 2.4
7.0 10.9 3.2 1.2
8.0 14.0 4.1 1.6
9.0 17.4 5.1 1.9
10.0 21.1 6.2 2.3 1.0
11.0 25.2 7.4 2.8 1.2
12.0 29.6 8.8 3.3 1.5
13.0 34.3 10.1 3.8 1.7
14.0 11.6 4.4 2.0
15.0 13.2 5.0 2.2
16.0 14.9 5.6 2.5
17.0 16.7 6.3 2.8
18.0 18.5 7.0 3.1
19.0 20.5 7.7 3.4
20.0 22.5 8.5 3.8 1.0
25.0 12.8 5.7 1.5
30.0
Pressure Loss
Excessive as Flow
velocity is > 12 ft/sec
18.0 8.0 2.2
35.0 10.7 2.9
40.0 13.7 3.7
45.0 17.0 4.6
50.0 5.6
55.0 6.6
60.0 7.8
65.0 9.0
70.0 10.4
75.0 11.8
Note: Pressure loss based on Hazen-Williams formula (C = 150).
Pressure loss for actual length can be calculated by following formula:
Actual length / 100 ft x value from chart above.