Click here to enlarge image"In a smaller water treatment facility, say in a town of about 10,000, the city engineer and his staff may wear several different hats," said Rand Underwood, sales manager for K-Tork. "One day they might be doing road repairs, and the next day working in the water plant. But a pneumatic actuator with one moving part is simple to work on. If the guy can use a screwdriver or a wrench, he can pretty much understand how to fix a K-Tork vane actuator."
Given the advantages inherent with rotary actuators — coupled with the fact that they are generally less expensive than electric actuators — facility engineers are installing them in water works plants with growing frequency.
Some vane actuator designs come ready equipped for mounting into existing plants, while others don't.
"One problem is that the manufacturers of valves don't necessarily make the mounting hardware for retrofit," Underwood said. "That leaves a facility engineer or a supplier with the responsibility of sketching something out on a piece of paper and taking it to a local machine shop. 'I need some plates with some holes drilled in this pattern.' That's generally the way it occurs."
For challenging retrofits, some rotary-actuator manufacturers, send their experts out into the field to help facilitate the installation process. Factory personnel or a qualified representative does the survey on the valve and returns to the factory with the dimensions and recommended actuator sizing.
K-Tork offers seven sizes of actuators, with torque outputs up to 150,000 inch/pound and adjustable rotations from 80 to 100 degrees. Integral limit switches and positioners are installed. The mounting plate is then fabricated, set-up and tested with the actuator. This process also includes the correct control module to interface with the plant's existing PLC, SCADA or even older pneumatic systems. The actuator is then shipped to the plant with the correct valve mounting kit.
Such turnkey installation procedures make it easy for plant managers on a tight budget to initiate plant upgrades from maintenance money.
Conclusion
Given the lowered costs, operational advantages, and ease-of-installation afforded by pneumatic vane actuators, water treatment managers are awakening to this new option for optimizing their water production, avoiding downtime due to maintenance problems and remaining within federally mandated turbidity levels.
"Regulating agencies get very picky about when you take filters out of action," Underwood said. "They don't want a community or municipality to be without water. Plant operators just can't shut their plants down whenever they want to. So aside from the fact that the accurate control made possible by rotary actuation helps lower turbidity levels, it is their reliability and low cost of ownership that really matters to most plant managers."