Valve Actuation & Automation

By Joseph Uwoajega – Consultant

An actuated or automated valve is a valve that is mechanically operated by a hydraulic, electric or pneumatic actuator. 

An actuator is a control mechanism that is operated by an energy source. The energy can be hydraulic pressure, pneumatic pressure, or electric current that drives the internal mechanical parts of the actuator. A valve actuator can also be described as a black box, having an input (power supply or signal), an output (torque), and a mechanism or circuitry to operate a valve.

Actuators can be designed to fail open (in the case of actuator failure, the valve will stay open) or fail close (in the case of actuator failure, the valve will stay closed).

Types of Valve Control Mechanisms

Double-acting actuators have air or liquid supplied to both sides of the piston with one side at higher pressure, which achieves the movement required to actuate the valve. This configuration uses pneumatic or hydraulic pressure of the air or liquid energy to open and close the valve.

Spring-return actuators have air or liquid supplied to only one side of the piston, and the energy to move the mechanisms comes from a spring on the opposite side. This configuration uses pneumatic or hydraulic pressure of the air or liquid to open or close the valve, and a spring affects the opposite motion.

Pneumatic actuators utilize compressed air to generate the energy required for the actuator. These actuators have high response time but are not ideal for environments under high pressures because gas is compressible. Pneumatic actuators are available in spring-return and double-acting designs.

Hydraulic actuators use liquid as source energy to apply pressure to the actuator’s mechanical components. They can exert a large amount of force because liquid is not compressible but is generally limited in acceleration and speed. Hydraulic actuators are available in spring-return and double-acting designs.

Gas over-oil actuators use high-pressure gas supplied from the pipeline suspended above a hydraulic fluid to drive the mechanics of the actuator. Gas-over-oil actuators are available only in double-acting configurations.

Electric actuators use an electric source, such as a battery, to power the actuator. They usually include intricate electrical circuitry. Because of their use of electricity as a power source, they may not be ideal for remote installations.

With the current trend of automated machinery and systems, there has been increasing demands for actuators, which play a vital role in the automation process.

Solar actuators play a vital role in solar energy generation by providing desired motion to the equipment used. They are utilized to automate the functioning of various solar tracking devices, solar power concentration equipment, photovoltaic devices, and photovoltaic concentration equipment, among several others.

Military actuators are basically installed in tanks, cannon carriers, airplanes, fighter planes, helicopters, ships, and robots, because they offer complete movement. They are ruggedly built to withstand harsh environmental conditions, extreme weathers, and severe attacks.

Actuators for warehouses rely on the highly advanced automated systems to optimize logistics management, and related activities. A wide range of actuators are being used in the making of robotic systems, conveyor units, forklift units, among others to provide superior performance in terms of precision, power and speed of operation.

Actuators for construction depend on high speed automated machines and systems to carry out several dangerous and tedious tasks. Actuators of varied types are used in these systems, because they are known to deliver powerful movements to heavy duty machinery like loading trucks, towing trucks, and cranes. Actuators for the construction industry are built to offer durable, reliable and long-lasting performance.