Isolation valves

Isolation Valves are considered on/off because they typically operate in two positions; the fully open and fully closed position (thus on/off). Valves made specifically for on/off service are designed with tight reliable shutoff in the closed position and little restriction in the open position. Ball valves, gate valves, butterfly valves, diaphragm valves and plug valves are the most commonly used isolation valves.

• Ball Valves
  were a welcomed relief to the process industry. They provide tight shutoff and high capacity with just a quarter-turn to operate. Ball valves are now more common in 1/4"-6" sizes. Ball valves can be easily actuated with pneumatic and electric actuators.
• Butterfly Valves
  have come a long way from the old damper valve days. Today's butterfly valves are designed for general as well as severe service applications. Resilient liners provide tight shutoff in general service applications. Triple offset metal seated butterfly valves are designed for severe service applications. Butterfly valves are the most economical valves per comparable capacity and are easily automated with pneumatic and electric actuators.
• Diaphragm Valves
  are by far the simplest valves. A resilient diaphragm provides tight shutoff and isolates the body from its operator. The operator consists of a plunger and handwheel assembly. Diaphragm valves are ideal for corrosive, slurry and sanitary services. They are easily and inexpensively actuated with pneumatic and electric actuators.
• Float Valves
  automatically control liquid level and prevent overfilling tanks. The valve is operated mechanically by a float which rests on the top of the liquid. As the liquid level rises, it pushes the float up and closes the valve. As the level falls, the valve opens. The amount of liquid pressure the valve can shutoff against is determined by the length of the rod and size of the float for a given valve size.
• Gate Valves
  have a sliding disc (gate) which reciprocates into and out of the valve port. Gate valves are an ideal isolation valve for high pressure drop and high temperature applications where operation is infrequent. Manual operation is accomplished through a multi turn handwheel gear shaft assembly. Multiturn electric actuators are typically required to automate gate valves, however long stroke pneumatic and electro-hydraulic actuators are also available.
• Globe Valves
  have a conical plug which reciprocates into and out of the valve port. Globe valves are ideal for shutoff as well as throttling service in high pressure drop and high temperature applications. Available in globe, angle, and y-pattern designs. Manual operation is accomplished through a multi-turn handwheel assembly. Multiturn electric actuators are typically required to automate globe valves, however linear stroke pneumatic and electro-hydraulic actuators are also available.
• Plug Valvesare similar to ball valves except instead of a spherical element, a cylindrical element is used as the internal restriction. Plug valves are typically more expensive than ball valves, but they are inherently more rugged as well. The plug is guided by a sleeve which acts as the sealing member. Plug valves require more torque to operate than ball valves, but are easily automated with quarter turn actuators. Plug valves are also available in 3-way and 180º configurations.
• Solenoid Valvesare simple electrically operated devices. The valve plug is held in place by a spring. When electric power is applied to the solenoid (Energized), the current draw through the coil generates an electromagnetic force which opposes the spring, causing the plug to change position. When power is taken away (De-energized), the spring returns the plug to the normal position. Solenoid valves are ideal for fluid shutoff and switching in general service applications.