Brochure

173F-27855-10
VB-2000 Series Ball Valves
with SmartX Actuators
26 | schneider-electric.com Selection Guide
January, 2019 tc © 2019 Schneider Electric. All rights reserved. All trademarks are owned by Schneider Electric Industries SAS or its affiliated companies.
Document Number: F-27086-14
Cavitation Limitations on Valve Pressure Drop
A valve selected with too high a pressure drop can cause erosion and/or wire drawing of the flow characterizing insert. In addi-
tion, cavitation can cause noise, damage to the valve trim (and possibly the body), and choke the flow through the valve.
A valve selected with too high a pressure drop can cause erosion of seals and/or wire drawing of the seat. In addition, can cause noise, damage to the
valve trim (and possibly the body), and choke the flow. Do not exceed the maximum differential pressure (pressure drop) for the valve selected.
The following formula can be used on higher temperature water systems, where cavitation could be a problem, to estimate the maximum allowable
pressure drop across the valve:
P
m
= 0.5 (P1 – P
v
)
Where:
P
m
= Maximum allowable pressure drop (psi)
P1 = Absolute inlet pressure (psia)
P
v
= Absolute vapor pressure (psia)
Note: Add 14.7 psi to gauge supply pressure to obtain absolute pressure value.
For example, if a valve is controlling 200°F water at an inlet pressure of 18 psig, the
maximum pressure drop allowable would be:
Pm = 0.5 [(18 + 14.7) – 11.53] = 10.6 psi
(Vapor pressure of 200°F water is 11.53 psia)
Systems where cavitation is shown to be a problem can sometimes be adjusted to provide higher downstream back pressures. Valves having
harder seat materials should be furnished if velocities are excessive.
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
0102030405060708090100 110 120
130
Maximum
∆
P of Valve (psi)
Inlet Pressure to Valve (psi)
50 °F Water
140 °F Water
160 °F Water
180 °F Water
200 °F Water
220 °F Water
Cavitation Zone
1
1 Maximum allowable ∆P for a valve with 45 psi
and 50 °F water is 30 psi, based on cavitation.
Figure 11. Maximum Allowable Differential Pressure (DP) for Water Valves.
8. VBB/VBS and VB-2000 Series
Ball Valve Assemblies
8. VBB/VBS and VB-2000 Series
Ball Valve Assemblies