Hi,

I cant believe no one responded. Try calling Wood Group Pressure Control 44 1224 840000 they will be glad to give you full info on an excellent range of Choke Valves

Chokes aren't my specialty but I'll give it a go.

Two basic types positive and adjustable. Positive are non-adjustable the orifice or 'bean' is changed to adjust flow.

Of adjustable there are the following types: Needle, MOV (multi orifice valve), plug & cage, & tapered plug, (there are probably more). Which one is appropriate depends on the application.

They can be manually operated or actuated. Actuation is whatever you want it to be, manual, hydraulic, pneumatic diaphragm, pneumatic piston, electric.

Check out www.weirvalve.com. You should be able to print the info. you need.

Re Various Design of Choke Valves, please ask for the Xt values (supposed to have been tested and published by each valve manufacturer for each of their own valves according to ISA procedure S75.02; see also S75.01) entered as control valve catalog information.
If Xt is less than x times Fk, then the valve will choke, where x is the ratio of the pressure drop (P2-P1)to the inlet pressure (P1) of the control valve; pressure in absolute units; Fk is the ratio of the specific heat
ratios, i.e. [Cp/Cv] of gas to [Cp/Cv] of air. Fk is formally called the Ratio of specific heat factor.  Most globe valves have Xt = 0.75.  For severe applications, look for control valves with Xt = 1, (such as angle valves with disk design) completed with calculated trim exit fluid Kinetic Energy (to be less than 70 psi), for most applications.  For steam venting, this trim exit fluid Kinetic Energy should be less than 1 psi. Email me if you want a control valve specification that I wrote for my Company. Also see P. 438, Practical Guide for Measurement and Control, Control Valves, Borden, ISA, 1998.

4carats

You can contact 4carats at liu.gerald@syncrude.com.