《Valve Selection》.pdfVIP

Valve Selection Valves isolate, switch, and control fluid flow in piping systems. Can be operated manually (using levers or gear operators) or remotely (using electric, pneumatic, electro-pneumatic, and electro-hydraulic powered actuators). Manual valves are usually used only if they will be operated infrequently or no power source is available. /menu/select.html Basic Valve Types Isolation valves: on/off valves Typically operated as fully open or fully closed Designed to have a tight reliable seal during shut-off and minimal flow restriction when open Switching valves: converge or divert flow in a piping system Control valves: used to modulate flow (i.e., vary flow by opening or closing by a certain percentage) 1 Isolation Valves Ball valve a ball with a hole through one diameter that can be rotated to align with the flow or block it They provide quick, tight shutoff, high capacity, and require only a ¼ turn to operate Can be actuated with pneumatic and electric actuators Isolation Valves Plug valve Similar to a ball valve except that a cylinder is used instead of a sphere More expensive but more rugged than a ball valve Require more torque to turn but still easy to actuate Can be used as a three-way valve, too 2 Isolation Valves Butterfly valves Can be used for both general and severe applications Liners help to provide tight shutoff The most economical valves per comparable capacity and easily actuated with pneumatic and electric actuators Isolation Valves Diaphragm valves Very simple Plunger and handwheel often used to apply