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:
CONTROL VALVE SELECTION INFORMATION
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