Burkert Fluid Control Systems, a manufacturer of control and measuring systems for fluids and gases, has unveiled 8690, 8691 and 8695 valve control heads, developed for use in the food, beverage and pharmaceutical industries, which according to the company, eliminate energy losses from wasteful venting of control air.

The company said that the valves provide a decentralized method of opening and closing of process valves automatically. At present, the majority of pneumatically piloted valves on production and process lines centralize pneumatic control around valve islands in a control cabinet or enclosure.

Thus the pipework carrying the pilot pressure to the actual valve from the valve island can travel for many meters before it reaches the valve head. As a result, the venting cycle of the valves operation exhausts proportionately more air than is necessary.

The Burkert control heads integrate electrical and pneumatic control components and position feedback units and, optionally, field bus interfaces for AS-Interface or DeviceNet. 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, the company said.

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 (parallel) directly into the valve.

Similarly, adopting digital positioners with integral solenoid valve control heads for regulating modulating process control valves will automatically lead to air savings, 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 twenty valves in operation; a large process site can therefore be using a vast amount of energy – unnecessarily.

Choosing the option of an embedded PID process controller, working in conjunction with the positioner, provides a fast-acting, decentralised control loop in combination with the associated process sensor. This arrangement also reduces complexity and saves unnecessary components and wiring, the company said.