Monthly Archives: October 2019

fluid velocity requirements,based on the vpour pressure

In general,the damaging effects of cavitation are a typical signal that fluid velocities are not being controlled.High fluid velocity and insufficient staging will result in interstage cavitation damage,reducing the effectiveness of the valve as a flow modulating device and exposing the trim to damage,whiche lead to a leaking valve.fluid vlocity requirements based on the vapor pressure(at design temperature),is governed by the following equation: V=sqrt(1000*(P2-Pv)/gravity).

continuous service single phase fluid : 30m/s

cavitation & multi-phase fluid :23m/s

Vibration-sensitive systems :12m/s

REcommanded flow velocities for liquids

1.Segment ball globe eccentric rotary plug:

Inlet velocity <= 10m/s(23ft/s) for continuous duty

Inlet velocity<=12m/s(39ft/s) for infrequent duty

2.Butterfly

Inlet velocity<=7m/s(23ft/s) for continuous duty

Inlet velocity <=8.5m/s(ft/s) for infrequent duty

technical data

1) Version with set points from 0.1 to 10 bar
2) For unbalanced versions with FKM diaphgram or FKM soft seal
3) Version with force limiter
4) Special version for set point ranges 0.8 to 2.5 bar, 2 to 5 bar, and 4.5 to 10 bar: pressure tapping directly at the valve body