Use And Care Manual

Flow meter with built-in flow rate balancing valve fully open
Shut-off valve
Cv
2.14
2.90
Supply or r
eturn manifold 3 to 7 outlets
Supply or return manifold 8 to 13 outlets
Ball valve
Cv
24.3*
17.3*
54.9
* Average value
(psi) (kPa)Δp (psi)
0.01
0.1
0.02
0.03
0.05
0.2
0.3
0.5
0.1
1
0.2
0.3
0.5
2
3
0.04
0.4
1
5
50
100
Q (l/h) (
gpm
)
0.1 0.2 0.5
200
1 2
0.01
0.1
0.02
0.03
0.05
0.2
0.3
0.5
0.04
0.4
1
(psi) (kPa)Δp (psi)
0.01
0.1
0.02
0.03
0.05
0.2
0.3
0.5
0.1
1
0.2
0.3
0.5
2
3
0.04
0.4
1
5
500
1000
Q (l/h) (
gpm
)
1 2 5
2000
10 20
0.01
0.1
0.02
0.03
0.05
0.2
0.3
0.5
0.04
0.4
1
Cv = flow in gal/min for a pressure loss of 1 psi
Example of how to calculate the total pressure loss
Suppose we need to calculate the pressure loss of a manifold with three circuits with the following characteristics:
Total manifold flow: 3.0 gpm (400 l/h)
The characteristics of the three piping loops are as follows:
Loop Flow (gpm) Tube length (ft) Δp (psi)*
1 0.7 150 1.13
2 1.3 300 6.90
3 1.0 300 4.32
*Δ
p Value for each loop calculated from data published by tubing manufacturers
Each segment of the formula (1.1), is calculated using the following relationship:
ΔP=Q
2
/Cv
2
· Q= flow in gpm
· ΔP = pressure loss in psi
· Cv = flow in gpm through the device in question, with a pressure loss of 1 psi
Important: ΔPTot must be calculated taking into account the circuit with the greatest pressure losses distributed along the entire piping loop
of the panel.
The circuit in question in our example is circuit 2.
Thus:
ΔP
BV
= 1.3
2
/2.14
2
= 0.37 psi
ΔP
Loop
= 6.9 psi
ΔP
SV
= 1.3
2
/2.90
2
= 0.20 psi
Using the formula (1.1) we can add all the calculated terms to obtain:
ΔP
Tot
= 0.37 + 6.90 + 0.20 = 7.47 psi
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