Valve control heads eliminate air bleed, cut energy and waste

By Rory Harrington

- Last updated on GMT

Related tags: Control theory

The use of three new valve control heads can boost efficiency and allow processors in the food, beverage and pharmaceutical industries to make energy and waste reductions, Burkert Fluid Control Systems has said.

The UK-based company has developed its 1066, 8631 and 8692 valve control head ranges to provide a decentralized method of opening and closing process valves automatically.

With valves, pumps and fans widely used in food and beverage production, the possibilities for energy savings are considerable, maintained the company, particularly as generation of compressed air to operate them is equivalent to about 10% of industry’s total electricity usage, rising to 30% in some sectors.

Reducing compressed air use

Improved process valve control techniques can lead to reduced compressed air use through the adoption of on-actuator or in-actuator pneumatic solenoid valves. The majority of pneumatically piloted valves on production and process lines centralise pneumatic control around valve islands in a control cabinet or enclosure. This means that the pipe work carrying the pilot pressure to the actual valve can travel for many metres before it reaches the valve head. As a result, the venting cycle of the valve’s operation will exhaust proportionately more air than is necessary, Burkert explained.

The firm said the advantage of employing the valves eliminates the need for the wasteful venting of control air normally associated with pneumatic tubing between the process valve and its related solenoid valve.

A company spokesperson told FoodProductionDaily.com: “They are mounted directly above the valve body, and, because there is little or no distance between the actuator and the valve that it is piloting, there is no air bleed: it is sealed.

“With this system the pressure feed goes directly into the valve head and the control signal is supplied either from a local closed loop control sensor or switch; or from a PLC/ machine controller via a control bus - AS-Interface or DeviceNet – or multipole directly into the valve.”

Digital positioners

The firm said similar air control savings can be gained by adopting digital positioners with integral solenoid valve control heads for regulating modulating process control valves - as these will normally ensure zero-air use in their stable state.

The traditional technique of process valve positioners incorporating pneumatic flapper-nozzle systems means that air is being bled constantly, even when the valve is at rest.

“This can average the equivalent of a 0.75kW (or one-horsepower) in compressed air for every ten to twenty valves in operation; a large process site can therefore be using a vast amount of energy – unnecessarily,”​ said Burkert.

Wastage

Issues around wastage can be improved by Burkert’s new 8201 and 8221 units, which accurately monitor process fluids by employing innovative techniques of pH and conductivity measurement, claimed the company.

Where probes are made to a high-standard of surface finish, combined with the use of glass-free food quality materials, the opportunity now exists for measuring and controlling process lines during all phases of production and cleaning, added the firm.

The ability of both the 8201 and 8221 units to stay in place over long periods means that requirements for recalibration become infrequent, decreasing manual intervention and downtime.

Related topics: Processing & Packaging

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