Specifying And Using Actuated Valves In The Process Industries

Actuated valves have become more and more prevalent within the process industry over the past few years, due to their accurate and efficient flow control. So perhaps it is no surprise that the market for valves and actuators is predicted to show strong growth over the coming years too.

Here, Les Littlewood – Sales and Marketing Director at Albion Valves (UK) Ltd., explores the options for those specifying and using actuated valves

David Keys, Managing Director at Albion Valves (UK) Ltd comments: “Due to the increased demand for actuation, the range has increased in line with our other product ranges with the aim to provide a complete solution from under one roof.

Our actuated range now includes stainless steel, brass and cast iron in a variety of formats such as ball and butterfly in either two or three-way configurations. We also have a choice of actuators – Direct Acting, Spring Return and Electric. All our valves come with a standard ISO mounting making assembly with any type of actuator simple and straightforward”

With such choice, can come confusion. So, for those who may not be involved in specifying or buying actuated valves on a regular basis, it’s worth remembering a few basics.

Control v Isolation Actuation

Within the process industries, actuation is usually used in one of two potential applications – either control or isolation.

Modulating control valves are used to regulate the flow of liquid to control a process, these valves allow for precise control over the medium that is required.

In comparison an isolation valve is simply used for a complete shut-off, so the valve will fully open or fully close as required.

When the type of valve has been established, the specifier would then need to select an actuator to complete the actuation package. For this it is important to know the type of environment it will be operating in. A number of factors would need to be considered here such as:

• ​Is air or electricity available?
• ​Are there any concerns over ‘clean’ operation?
• ​Does the application represent a harsh or corrosive environment?

After the answers to these questions have been provided, it should dictate which type of actuator would be the most suitable, principally pneumatic or electric for process applications.

Pneumatic v Electric Actuators

Pneumatic actuators are powered by compressed air or gas and generally high force and speed at a low unit cost and in a relatively small operating footprint. Pneumatic cylinders provide more force and speed per unit size than any other actuator technology except hydraulic.

Electric actuators use an electric motor to provide torque to operate a valve. The advantages to an electric actuator are that they are quiet, non-toxic and energy efficient. Electric actuators are available in a wide range of voltages including 24VAC, 24VDC, 110VAC, 220VAC and 380V.

When compared to pneumatic actuators, electric actuators are more economical when they are placed in small to medium applications, as opposed to large-scale, as they provide precise control and positioning.

Approvals

After a valve and actuator has been selected it is important to check that both the valve and the actuator have the necessary approvals for the job. For example, if the actuation package is going to be used on a potable water line it is important that the valve has a WRAS approval.

Or if the pipe medium is highly flammable, it is important that both the valve and actuator are ATEX approved and fire safe.

There is no set answer as to what type of valve and actuator package is best as it is solely dependent on the application and environment, so our advice is simple – if in doubt – Ask.