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Diaphragm valves for aseptic applications0 pages
Flow Rate and Valve Sizing
In order to design valves for a process system correctly,
the valve size is determined by the required flow rate.
The Kv-value serves as a calculation basis for the different
process conditions.
This value is stated in the following table with regard to
nominal diameter and standards.
Conversion:
For the correct Kv to Cv conversion calculation, use only
the stated units formulas below.
The Kv-value must be converted from (cubic meter / hour)
by utilizing the following conversion factors.
In the US the flow rate of water is measured with the
Cv-value in US-gallons per minute (gpm) with a pressure
drop of p 1 PSI.
Kv-value
Conversion of Kv to Cv
Cv = 1,17 x Kv
The Kv-value is a parameter defining the flow rate of
valves. It describes the amount of water from 5° to 30°C
which flows through the valve at a pressure loss of 1 bar.
The Kvs-value describes the Kv-value when the valve is
100% open.
For water 5-30°C applies:
Kv =
Q
p
Conversion of Cv to Kv
Kv = 0,86 x Cv
Explanations:
Kv
m3/h
Q
m3/h
kg/m3
p1
bar
bar
p2
bar
p
flow rate parameter
volume flow rate
specific gravity
pressure before the valve
pressure after the valve
pressure drop through the valve
p = p1 - p2
Iso 1127
Code 40
Code 41-43
Code 45
4
6
8
10
15
1/4"
3/8"
1/2"
8
8
8
8
8
-
-
2,4
-
2,3
-
1/4"
3/8"
1/2"
3/4
10
10
10
10
2,7
3,9
5,3
-
2,5
4,7
5,5
1/2"
3/4"
1"
25
25
25
10,5
9,5
11,5
14,2
43,0
52,0
89,0
123,0
192,0
32
40
50
65
80
100
Test stand to determine and document flowrates and Kv (Cv) values
1 1/4" 40
1 1/2" 40
50
2"
2 1/2" 80
80
3"
100
4"
13,0
15,5
43,0
50,0
64,0
95,0
127,0
205
0,7
1,4
1,4
2,2
4,6
188/195/307
289/295/397
2,0
2,2
6,8
12,0
40,0
48,0
85,0
110,0
385/402/407/495
985/995/997
p
MA
15
20
25
1000
NPS
8
10
15
20
Kv = Q
DIN 11850 ASME-BPE
DN
190/207
290/297
Nominal diameter
General Liquid Flow Formula:
Valve type
Kvs-Value (m3/h)
185,0
The Kvs-Values in the table refer to the specification with two-way
valves with EPDM diaphragm (Depending on the specification
variations are possible).
All leaets are available on: www.asconumatics.co.uk
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