When Actuators Become Necessary
One of the most useful and under-appreciated inventions in the world of rotating equipment and valves is most definitely the valve actuator. This is because without an actuator, many industrial processes requiring a valve would become much, much more time-consuming, if even still possible at all. Actuators “control the opening and closing of valves. They can provide either linear or rotary motion and work with different types of valves, including ball and butterfly valves.”1 Though as crucial as actuators are for larger valves used downstream & midstream in the petroleum industry, an actuator is not always required.
A major requirement for installing an actuator is the amount of torque required to open and close a valve. If, for example, a small butterfly valve in a chemical plant requires only a minimal amount of torque to be applied before it is fully closed or fully open, it may be advised to not install an actuator. However, if this same butterfly valve were to be required to open and close hundreds of times each day, then a valve actuator would be crucial to install if for no other reason than for the sake of saving time. Hence, we see that torque and amount of times a valve must be open and closed are major requirements for a valve actuator’s installation.
Still, this leaves room to inquire about which specific type of actuator to use for ball valves. “There are three basic types of automatic valve actuators: those that are controlled by pressurized air, by electrical power, or by hydraulic force.”2 The pneumatic actuator, as its name suggests, utilizes pressurized air to open a valve. The best application for a pneumatic actuator is for rotating ball valves, as it is rather fast in its stroking speeds. Another common actuator is the electric actuator, which utilizes electricity to drive a valve open/closed “by means of gear couplings. Solenoid valves use electric power to attract a magnetic slug attached to the valve stem and are used in automatic open-close applications.”3 Actuators can sometimes be rather expensive, especially when needed for a larger valve requiring many thousands of psi to open.
The valve actuator is so very useful that it is arguable that actuators might as well be a requirement for opening and closing valves. But some valve actuators can be rather expensive for such a rather minute task of opening and closing a valve. When dealing with a great barrier of resistance to open and close a valve, much time can be saved with an actuator, as is seen previously. When considering the initial price of an actuator, it may be tempting to simply disregard a valve actuator– and that may be acceptable for some valves which are left static for long periods of time– yet if a valve takes a great deal of time to open and/or is frequently opened/closed, it would make much more sense for a valve to house an actuator for the sake of saving time and preventing any accidents when attempting to open/close the valve. Again, if for only the sake of gaining partial efficiency and saving time, a valve actuator is worth its initial cost.
Valves and actuators make for an excellent, efficient, safe team in the valve world. It’s helpful and many engineers would highly advise utilizing actuators to gain the full potential out of a ball valve, butterfly valve, etc. While EMC does not make any recommendations to customers over these articles, it is clear that actuators are not always required, yet in many cases, a valve actuator *should* be applied regardless for the sake of efficiency in both the operation of a valve, as well as time-saving for the operation of opening/closing a valve.
3 Same as 2
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