Q&A: Trends in Valve Actuation

Tom Carlson has been the valves and actuation product manager for George Fischer Inc. for the past three years. Prior to joining George Fischer, Mr. Carlson served as a product manager for Bimba Manufacturing for nine years. Bimba is a manufacturer of stainless steel pneumatic actuators and flow controls. Mr. Carlson earned a bachelor’s degree in Ceramic Engineering from the University of Illinois and an MBA from Governor”s State University in Illinois. He can be reached at [email protected] or 714 731-8800.


Q: How has the actuated-valve market evolved over the past five years, and how has the technology changed to meet new user needs?

A: The actuated valve market has diverged into a couple of distinct categories, both driven by economic needs. On one hand the actuated valve market has become more commoditized, requiring simple on-off actuated packages at extremely low pricing. On the other hand, customers are asking for increased technological capabilities. Valves that offer increased technical capabilities resulting in less downtime, improved system communication, and troubleshooting are in high demand. Users are looking for improved system efficiency and capability, while at the same time lower overall system costs.


Q: How does an electric valve actuation system differ from a hydraulic or pneumatic valve actuator?

A: Electric actuation offers the most reliable actuation technology available. It offers the best accuracy and control, period. It also offers the most system flexibility and system integration capability. Electric actuation is also probably the most convenient because electric power is both readily available at most facilities and is easily portable. Hydraulic and pneumatic actuated systems require hydraulic or pneumatic systems to be established in the plant. Additionally, hydraulic and pneumatic systems offer less control and flexibility. It is also fair to note that pricing reflects these differences.


Q: Specifically, what complexities does the trend toward miniaturization in the actuated-valve market present for a manufacturer of this type of technology?

A: Miniaturization poses similar general complexities across all products and industries. Customers desire more capabilities in a smaller package. The smaller the package, the smaller the system or skid. Our biggest challenge is understanding our customers” needs and optimizing the ratio of their size requirements with the capabilities of the actuated valve they desire. Of course every customer has different needs, so the ultimate challenge as a manufacturer is to offer a design that allows customers the flexibility to choose and build to their requirements.


Q: What sort of positioning accuracy can electric actuated valves offer? How does that accuracy compare to a hydraulic or pneumatic actuated valve?

A: As valves become more intelligent, the best accuracy is needed to take advantage of this increased valve intelligence/capability. As I said earlier, electric actuation offers the best accuracy, especially when accuracy involves mid-stroke control, such as for flow control. Pneumatic actuators use air as the power source. Air is compressible, so the accuracy is rough in between the two hard stops that are associated with open and closed. Hydraulic actuators are less susceptible to inaccuracy, but electric control is still preferred and the best choice when looking for accuracy.


Q: How does an electric actuated valve address hysteresis and stiction (i.e., static friction)?

A: Hysteresis can be minimized by using a "smarter" valve — a valve that knows its position using position-sensing switches or a positioner — to offer the most finite control. Stiction should be reduced with an improved valve design that minimizes the friction in that valve. Using near frictionless materials, optimizing seal cross-sections and squeeze, and proper lubrication, all influence valve stiction. The power of the actuator also assists with overcoming the affects of stiction.


Q: How do you see actuated valve technology evolving over the next five years? How can the technology improve?

A: Actuated valves will continue to become more capable or smart, thereby becoming more integral in the control process by more directly communicating with an entire system. I suspect technology will also continue to drive costs lower, while providing users with improved flexibility and control as well. It”s tough to say exactly how the technology will improve specifically, but the United States is slow in adopting or converting to any bus communication protocol, which delays improvements in automation technologies, such as actuated valves.

For More Information: www.us.piping.georgefischer.com