Electrical Actuators
Electric motors have long been used to actuate large valves, especially valves operated as on/off (“shutoff”) devices. Advances in motor design and motor control circuitry have brought motor operated valve…
Dampers and Louvres
A damper (otherwise known as a louvre) is a multi-element flow control device generally used to throttle large flows of air at low pressure. Dampers find common application in furnace…
Rotary Stem Valves
A different strategy for controlling the flow of fluid is to insert a rotary element into the flow path. Instead of sliding a stem into and out of the valve…
Working Principle of Pneumatic Actuators
Pneumatic actuators use instrument air pressure to apply force on the diaphragm to move the valve actuator and then to position valve stem. The following photograph shows a cut-away control…
Working Principle of Hydraulic Actuators
Hydraulic actuators use liquid pressure rather than instrument air pressure to apply force on the diaphragm to move the valve actuator and then to position valve stem. Nearly all hydraulic…
Working Principle of Self Operated Valves
Although not a type of actuator itself, a form of actuation worthy of mention is where the process fluid pressure itself actuates a valve mechanism. The self-operating valve principle may…
How Ball Valves Work ?
In the Ball Valve design, a spherical ball with a passageway cut through the center rotates to allow fluid more or less access to the passageway. When the passageway is…
How Globe Valves Work ?
Globe valves restrict the flow of fluid by altering the distance between a movable plug and a stationary seat (in some cases, a pair of plugs and matching seats). Fluid…
How Gate Valves Work ?
Gate valves work by inserting a dam (“gate”) into the path of the flow to restrict it, in a manner similar to the action of a sliding door. Gate valves…
How Diaphragm Valves Work ?
Diaphragm valves use a flexible sheet pressed close to the edge of a solid dam to narrow the flow path for fluid. Their operation is not unlike controlling the flow…
