Positional Feedback Valves

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“Many industrial processes, such as power generation, mining, food manufacturing and chemical manufacturing, use a series of ball valves, and could benefit from positional feedback valves in certain applications,” says Lynette Morrey of Allmech, a South African manufacturer of boilers and supplier of water treatment components and the sole official agent in South Africa for Runxin water treatment systems.

The degree and angle that the ball can be opened at is determined by the PLC, and adjustments for flow, temperature and pressure can also be made. Positional feedback valves allow for accurate regulating of the exact angle that the ball valve opens and closes thus avoiding the inconvenience caused by mechanical positioning. They also reduce errors and generate an immediate alert if the ball valve is not operating correctly or is jammed. Furthermore, because they use standard connections, they are easily installed, adjusted or replaced. They can be mounted on a bracket for plastic or metal ball valves and are ideal for both indoor and outdoor use (although they require protection if exposed to extreme sunlight or weather conditions).

The position feedback signal ranges from 0-5V, while the controlling signal is 0.5V. The valve is DN25 size, with a female thread connection DC24V. Lynne adds, “It’s important to ensure that your power supply matches the valve model chosen, and that the flow direction matches the directional arrow on the valve body to avoid leakage. Remember also that the factory default on all ball valves is normally closed.

“Ensure the ball valve is resistant to the fluid or chemical it will be exposed to, and consider the quality of the water. Large particles (bigger than 0.2mm) or sediments in the water would require a pre-filtration system to avoid valve damage. Also remember that if the valve is opened up by an unauthorised technician, the manufacturer’s warranty will generally be voided.”

She suggests contacting a reputable valve supplier to undertake a site visit. “That’s what we do before we recommend the best solution and the correct ball valve for customers’ specific applications,” she says. “Our team is always available to offer assistance with troubleshooting having undergone comprehensive technical training from Runxin. All ball valves we supply carry a one-year manufacturer’s warranty.”

Tel: (011) 849-2731
lionelm@allmech.co.za
www.allmech.co.za