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Cavitation
Cavitation increases wear and tear of the ball and seat and results in unwanted noise.
Cavitation can be prevented by not exceeding the differential pressures as per the flow
diagram and maintaining the static pressures depicted below.
2500
2000
1500
1000
500
Δp
max
p
1
P
3
M
J
Example with hot water:
Pressure p
Water temperature: 120 °C
The above diagram clearly indicates that the maximum permissible differential pressure is
Δp
max
Note on chilled water applications
To prevent cavitation in chilled water circuits, sufficient counter pressure must be supplied to
the ball valve outlet, e.g. using an additional butterfly valve downstream of the ball valve.
Maximum permissible differential pressure over the ball valve: See 80 °C curve in the above
diagram.
Siemens
Smart Infrastructure
0
0
100 200 300 400 500 600 700 800 900 1000 1100 1200 1300
= Differential pressure at a nearly closed ball
valve to largely avoid cavitation
= Static pressure at the ball valve inlet
= Static pressure at the ball valve outlet
Pump
Water temperature
at ball valve inlet: 500 kPa (5 bar)
1
→ 200 kPa (2 bar) at a nearly closed ball valve.
25
20
15
10
5
0
2019-06-04
5
N4212en
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