Author Archives: ctrvalve

About ctrvalve

Select very low Dp control valve–

The industrial process conditions is very low pressure differential —-only 1KPa. control valve flow resistent factor need small. So select segment V-port valve. because fluid include small solid . The max shut off Dp unit should be 0.003Mpa .

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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


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

Self-operated valve with pilot valve for small pressure regulator of General safety instructions

1.The regulator is to be mounted, started up or serviced by fully trained and
qualified personnel only; the accepted industry codes and practices are to
be observed. Make sure employees or third persons are not exposed to any
2.All safety instructions and warnings given in these mounting and operating
instructions, particularly those concerning installation, start-up, and maintenance, must be strictly observed.
3.According to these mounting and operating instructions, trained personnel
refers to individuals who are able to judge the work they are assigned to
and recognize possible dangers due to their specialized training, their
knowledge and experience as well as their knowledge of the applicable
4.The regulators comply with the requirements of the European Pressure Equipment Directive 2014/68/EU. The EU declaration of conformity issued for a
regulator bearing the CE marking includes information on the applied conformity assessment procedure. This declaration of conformity can be provided on request.
5.To ensure appropriate use, only use the regulator in applications where the
operating pressure and temperatures do not exceed the specifications used
for sizing the regulator at the ordering stage.
6.The manufacturer does not assume any responsibility for damage caused by
external forces or any other external factors.
7.Any hazards that could be caused in the regulator by the process medium,
operating pressure or by moving parts are to be prevented by taking appropriate precautions.
8.Proper transport, storage, installation, operation, and maintenance are assumed.

Recommanded flow velocities for liquids

1.segment ball globe eccntric rotary plug: *Inlet velocity <= 10m/s continuous duty service, *Inlet velocity <=12m/s for infrequent duty

2.butterfly: *inlet velocity <=7m/s for continuous duty *inlet velocity <=8.5m/s for infrequent duty

3.Vsonic = 91.2 * SQRT(rT/M) r : specify heat T:temperature (K) M: moler mass

other kinetic energy equtions

1 . Vo=W/(M1PoAo) —->throttling velocity unit m/s
Ao—->valve throttling area :m2

2. KE = Po*Vo*Vo/(2*M) <Kpa> M=1000 Po: kg/m3 Vo:m/s

3. KE = Pc*C/(2*M) For gas and steam ,the fluid velocity at the trim outlet may be sonic.if it is the density of the fluid at the trim outlet must be higher than the outlet desity. in order to pass the given mass flow rate.This higher density can be estimated using Equation 1. by substituting the fluid’s sonic velocity for the outlet velocity and solving for density.then this density and sonic velocity are used in equation 2 to find the kinetic energy.

Velocity criteria for liquids are much lower than forgases because liquid densities are much higher,resulting in higher energy levels.while the velocity limits are quite different,the kinetic energy limits are very close to the same.

fluid velocity requirements,base on the vapor pressure of the fluid (at design temperature) is governed by the following equation: V=SQRT(1000*(P2-Pv)/p) v:m/s P2,Pv : Kpa p : kg/m3

COEFFICIENT = 0.0509*trim throtting area(mm2)/SQRT(flow path resistance coefficient)

the outlet density can be estimate form eqution: outlet density=previous density*outlet pressure/prev pressure.