Control valves abound in each and every section of industrial process control. Pneumatic control valves handle all sorts of fluids at temperatures in the cryogenic range to more than 1000°F (538°C). Choice of a control valve body set up requires particular shown to supply the best available mixture of valve body style, material, and trim construction the perception of the intended service. Capacity needs and system operating pressure ranges also should be considered when deciding on a control valve to make sure acceptable operation without undue initial expense.

Information needed to pick a control valve. Photo Credit : Fisher

The figures within the orange colored circles within the above control valve diagram matches the serial figures within the table below where we've because of the typical information needed to decide on the right control valve. For instance serial figures 1, 2, 3, 4, 5 represents fluid qualities akin to serial figures 1, 2, 3, 4,5 within the table below.

To possess a obvious knowledge of the data needed to pick a control valve which we've discussed in the following paragraphs, please browse the following:

How control valves are specified

Control valve body materials

Common terms utilized in control valve applications

Due to the inclination to obtain the choice of control valves wrong, most control valve manufacturers as well as their representatives have dedicated themselves to helping their customers choose the control valve most suitable for that existing service conditions. To assist in choosing the proper control valve, the next information should be provided prior to the actual sizing and buying process:



1    Type of fluid to become controlled    What fluid are you controlling? Water?, gas?

2    Temperature of fluid    State the worst scenario temperature from the fluid in degree F or Celsius

3    Viscosity of fluid

4    Specific gravity of fluid

5    Flow capacity from the control valve    State the utmost and minimum flow rates.

6    Inlet pressure at valve    State maximum and minimum inlet pressures likely to be handled through the control valve

7    Outlet pressure at valve    State maximum and minimum outlet pressures likely to be handled through the control valve

8    Pressure drop during normal flowing conditions

9    Pressure drop at turn off

10    Noise level    State the utmost allowable noise level if needed and also the measurement reference e.g 55 dBA

11    Degrees of superheat or information on flashing if known

12    Inlet and outlet pipeline size and schedule

13    State whether any special tagging details are needed for that control valve

14    Body material from the control valve    State the needed body material from the control valve - ASTM A216 grade WCC, ASTM A217 grade WC9, ASTM A351 CF8M, etc.)

15    End connections and valve ratings    Is it likely to be screwed? Class 600 RF flanged? Class 1500 RTJ flanges? etc

16    Valve action preferred when instrument air fails    Is the valve to fail open, close or maintains its last controlled position?

17    Instrument Air Availability    State if the valve require instrument air

18    Valve type number    Only when needed by manufacturer

19    Valve size

20    Valve body construction    Is the valve body likely to be position? double-port control valve? Butterfly valve? etc.

21    Valve port size    State if the valve port size will probably be full or restricted

22    State the preferred valve trim materials needed

23    Flow action    State whether flow will have a tendency to open valve or close valve

24    Actuator size    State how big actuator needed for that control valve.

25    Bonnet Style    Is the bonnet style likely to be plain, extension, bellows seal, etc.

26    Valve packing materials    State the kind of valve packing material - PTFE V-ring, laminated graphite, ecological sealing systems, etc.

27    Valve accessories    State the control valve accessories needed positioner, handwheel etc