Control valve selection is depend on below these points :

  •  Type of fluid to be controlled
  •  Temperature of fluid
  •  Viscosity of fluid
  •  Specific gravity of fluid
  •  Flow capacity required (maximum and minimum)
  •  Inlet pressure at valve (maximum and minimum)
  • Outlet pressure (maximum and minimum)
  •  Pressure drop during normal flowing conditions
  • Pressure drop at shutoff
  •   Maximum permissible noise level, if pertinent, and the measurement reference point
  •  Degrees of superheat or existence of flashing, if know
  •  Inlet and outlet pipeline size and schedule
  •  Special tagging information required
  •  Body Material (ASTM A216 grade WCC, ASTM A217 grade WC9, ASTM A351 CF8M, etc.)
  •  End connections and valve rating (screwed, Class 600 RF flanged, Class 1500 RTJ flanges, etc.)
  •  Action desired on air failure(valve to open, close, or retain last controlled position)
  •  Instrument air supply available
  •  Instrument signal (3 to 15 psig, 4 to 20 mA, Hart, etc.)
  •  Valve type number
  •  Valve size
  •  Valve body construction (angle, double-port, butterfly, etc.)
  •  Valve plug guiding (cage-style, port-guided, etc.)
  • Valve plug action (push-down-to-close or push-down-to open)
  •  Port size (full or restricted)
  •  Valve trim materials required
  • Flow action (flow tends to open valve or flow tends to close valve)
  •  Actuator size required
  • Bonnet style (plain, extension, bellows seal, etc.)
  •  Packing material (PTFE V-ring, laminated graphite, environmental sealing systems, etc.)
  •  Accessories required (positioner, handwheel, etc.)

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