Pneumatic Actuators
Because of the availability of compressed air or high pressure N₂ system in power plants, pneumatic type actuators are used more extensively than other types. The pneumatic type actuator derives its power from compressed air sources. The controlled release of this potential energy, driving the piston/rod assembly, provides the required force to actuate valves. Internal springs may provide the valves safety function with air or N₂ used to compress the spring.

Pneumatic actuators are easily adapted to gate valves, globe valves, butterfly valves, ball valves and dampers. They are available with 1-1/2 in through 38 inch bore diameters (with strokes as required) and utilized normal plant air supplies of 60-125 psig. If required, they can operate at pressures up to 750 psig. Spring closed/open actuators up to 250,000 lbs. force.

The pneumatic actuator can be fitted with stored energy sources such as spring, compressed air, or loadstone, they are also available in many configurations to satisfy failure mode requirements such as fail-closed, fail-open or fail-locked. Failure mode requirement such as fail-closed, fail-open or fail-locked.

In the nuclear power plants, there are "safety and non-safety" applications. They require "nuclear grade" actuators, some of which have the capacity to store energy and perform on command without fail.

Hydraulic Actuators
Hydraulic actuators are recommended when pneumatic types, in order to produce required thrust, become incompatible with the valve in terms of weight and/or size.

Hydraulic actuators have certain capabilities not found in pneumatic types... higher thrust and more precise position and speed control throughout the valve stroke.

They are available with bore sizes, through 24 inches. Depending on the trust requirements, hydraulic actuators can be designed with mechanical spring, hydraulic accumulator or electrometric stored energy sources. These actuators are designed incorporate control and accessory variations based on particular specification requirements (e.g., stored energy, redundancy of active components and remote surveillance). Our Hydraulic actuators are made with low maintenance in mind. Simplicity is the key combines with long term experience provide the lowest and easiest maintenance actuator in the industry.

Hydro-Pneumatic Actuators
This "combination" valve actuator draws on the best features of the pneumatic and hydraulic actuators. It's that combination of readily available air sources ant he non-compressible quality of oil which allows this actuator to provide precise speed control during conditions of rapid stream or water flow. The features of this combination are particularly important in main stream and feed water isolation service.

the pneumatic/hydraulic actuator is available with bores sizes ranging from 14 inches through 50 inches. this actuator is normally used in conjunction with springs as the stored energy source. However, other energy sources (such as locally stored compressed air) may be used when valve design configurations preclude the use of springs.