Problem of contaminant ingress into diaphragm valves solved

Ian Webster, Burkert's Hygienic Processing Field Segment Manager, says: "The feedback we are getting from contacts in the food and pharmaceutical sectors is that our competitors have not updated their diaphragm control valves - apart from the material of construction - to take account of demands for increased sterility in hygienic processing applications. By contrast, Burkert has changed not only its material of construction, to stainless steel, but also its design, and has evolved its valve range to make it more suitable for hygienic applications, including IP67 ingress protection."

The specific problem solved by Burkert's Element range concerns the interface between the valve actuator and the control head - or switch box. In many designs this interface provides a pathway for the ingress of moisture onto the spring (or springs) of the actuator, resulting in corrosion, contamination from biological growth, and impairment of the correct functioning of the actuator itself.

No ingress of ambient air

An innovation in valve actuator control on the Element valve units prevents this from happening. Valve actuator control is achieved by means of integrated pilot valves that can also be operated manually for easy local operation. For each operation, clean and dry control air is deliberately flushed into all areas of the actuator. This ensures that, unlike traditional approaches, ambient air is never drawn into the spring chambers and surrounding voids, thereby extending the valve's reliability and life and, at the same time, maximising process availability for the valve user.

In addition, as no impurities or moisture are drawn into the actuator, there can be no corrosion of the springs inside the actuator. The same feature also prevents the risk of biological growth, which could result in contamination of the process environment as a whole.

Burkert has also deployed new design thinking to provide protection against moisture ingress into the electronics of the control heads on the Element valves. Protection is required because small but naturally occurring changes in the control head pressure can lead to the penetration of moisture, particularly after a washdown cleaning process. Defence against this ingress is provided by diverting a small amount of clean control air into the control head, maintaining a slight positive pressure, thus achieving a simple and innovative product.

The Element Type 8802 valves for on/off and continuous control are part of Burkert's Element system, which provides a complete systems approach, linking clean line valves, sensors, positioners and valve actuators in a simple architecture for complete control loop processes. A modular system, Element saves processing time by offering total control for a range of media. For more information about the Element Type 8802 clean line range of diaphragm valves, go to www.burkert.co.uk.