Smart Electric Valve Actuators Operate as Fast as Pneumatic Actuators

Traditionally electric valve actuators could not be considered to replace pneumatic valve actuators where the fast opening and closing speeds that are standard in pneumatic actuators were required, resulting in the expense of installing an air compressor, air pipework, driers and filters to drive the air actuators. With far fewer moving parts air actuators can comfortably be used in applications where a high number of cycles are required, another ‘Achilles heel’ of electric valve actuators as the relevant European norm limits the performance of part-turn on-off electric actuators to just 10,000 cycles.

Some new smart electric valve actuators are now able to operate at speeds under 1 second making them contenders to replace costly compressed air systems and offering customers a real lifetime cost advantage. One application for fast-acting electric actuators is in filling systems, traditionally a stronghold of the pneumatic actuator.

J4CS recently tested an AVA S20 fast acting on-off smart actuator fitted to a 1” stainless steel ball valve from Actuated Valve Supplies in the UK and can report that the actuator operated the electric ball valve in 1 second effortlessly and faultlessly over a test of 30,000 cycles. It is clear from our test that the build quality of the AVA is high to withstand our test and we would not be surprised that the claim from the manufacturers’ UK agent that they have fast acting AVA modulating actuators in an application that have exceeded 6 million movements is true.

Modern manufacturing techniques have enabled the consistent production of highly accurate components which when assembled under quality-controlled conditions, produce products with a high build quality that result in accurate and reliable performance in service, and offer a long service life. Following our tests, our opinion is that the AVA electric actuator is an excellent example of the use of modern manufacturing techniques with an obvious and deep understanding of the benefits of strict attention to all aspects of quality control.

Improved Functionality from Smart Electric Valve Actuators

The design of smart electric valve actuators remained near stagnant for many years with most designs relying on the traditional cam and micro-switch solution to stop the motor. So-called design improvements often saw small changes to improve the design of the cams and switches, or the introduction of a brushless motor, for example, rather than a more radical change to the basic principals of operation.

Recent advances have seen a move towards digital control of the actuator’s position via digital magnetic positioning technology, which offers not only improved accuracy as it is digital but also a non-mechanical system which has obviously improved lifetime service implications compared to mechanical systems that are prone to ‘wear and tear’.

Whilst the elimination of mechanical components hints at improve total life cost as there as fewer parts that can fail, it is the switch to control of the functionality of the electrical actuator by software that is the more significant benefit. Employing brushless motors from the start, actuators like the AVA actuator available from Actuated Valve Supplies in the UK, recently tested by J4C-S have embraced modern technology and offer a dazzling list of standard and optional features, all controlled by software.

Combining a user interface comprising of a bright OLED screen and external push buttons, users not only have useful operational information displayed on the screen but have the ability to either control the electronic actuator locally, more commonly referred to a ‘local control’, but can make minor adjustments to several useful operational parameters that separates valve actuators like the AVA actuator from most rivals in its class, from a user perspective.

Features such as speed control, external adjustment of zero and span (open and closed positions) which in electric actuators with cams and switches requires the cover to be removed to access the switches, and external setting for 3 positions become standard features in software-driven actuators rather than ‘factory specials’ from manufacturers still using the original cam and switches design.

Copyright Journal for Control-Systems Engineering 2019
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