Install Instructions
6
48
103
20
10
150
28
35
62
117
90
68
5
10
2
1.5
20
3
15
7
1 in
1 1/4 in
3/4 in
1/2 in
FALL OFF PRESSURE
Reference values: Upstream pressure = 116 psi (800 kPa)
Downstream presssure = 43 psi (300 kPa)
14
∆
p (psi)
∆
p (kPa)
1 1/2 in
2 in
20
90
Flow rate
(/s)
(gpm)
30
40
10
5
2
1
0.9
5
50
60
70
1
2
0.5
0.2
0.1
0.05
3
4
6
1.5
0.3
0.4
2.5
80
3
4
Graph 2 (Pressure drop)
Sizing procedure
Maximum flow velocity is recommended to be kept within 3 to 6 feet per second when calculating
the correct pressure reducing valve size. This will prevent noise in the pipes and rapid wear of
appliances. Minimum flow velocity to prevent excessive wear on the valve and to reduce the
chance of noise due to low flow is 1 foot per second.
The correct size of the pressure reducing valve is taken from graph 1 on the basis of the design
flow rate taking into account an ideal maximum flow velocity of between 3 and 6 f/s (blue band).
Example:
For 8 gpm, select the ¾” size valve (see arrow on graph 1).
The pressure drop is taken from graph 2 also on the basis of where the design flow rate
intersects the curve for the valve size already selected (the downstream pressure falls
by an amount equal to the pressure drop, with respect to the set pressure at no flow
condition). Make sure the falloff pressure (pressure drop) of the chosen valve, at the specifed
flow rate, will result in the valve supplying the required pressure to the system fixtures.
Design Flow Rate
Size ½" ¾" 1" 1¼" 1½" 2"
gpm 4 to 7.3 7 to 12.5 10 to 19 17 to 34 24 to 44 37 to 70