A key feature of the Type 8681 control head is that it is universally adaptable, enabling it to be combined with all commercially available valve types, such as butterfly valves, ball valves and single and double-seat valves. In addition, the control head is manufactured from chemical-resistant materials, benefits from a high IP rating, and is very easy to clean, features that make it ideal for use in hygienic applications.
As well as universal adaptability, the Type 8681 is characterised by its ease of installation and operation and the level of interactive status control that it provides. These features enhance the 8681’s role as the centralised element in decentralised automation systems, performing all pneumatic actuation, feedback and diagnostic functions, as well as bus communication. Moreover, depending on process valve type, the 8681 is able to control up to three pneumatic actuator chambers separately.
Once the 8681 control head is installed on the valve actuator, the switching positions are automatically determined by a fast and reliable teach-in function that eliminates the requirement for manual configuration. The three integrated switching positions are measured by the control head via an inductive analogue position sensor and transmitted to a PLC. A fourth switching position can also be provided, if required, via an externally mounted inductive proximity switch
Complementing the feedback facility to a PLC, a highly visible colour-illuminated status display signals the respective switching position of the process valve. Diagnostic functions such as required maintenance or errors are also signalled visually and can be read out in detail via a service interface.
Also aiding operational flexibility with the Type 8681 is a feature that allows the switching speed of each driver chamber to be set individually for both directions of movement, by means of a restrictor function integrated into the pilot valve. In addition, a non-return valve prevents faulty switching of the process valves due to back pressure. Independently of the power supply, each pilot valve can be switched manually by means of a mechanical hand control. This patented magnetically- coded manual operation allows switching of the main actuator from outside a completely enclosed device – ensuring full IP protection also during maintenance on the process valve.
Commenting upon the launch of the Type 8681, Neil Saunders, Burkert’s UK Sales Manager, said that: “Decentralised automation of process valves, provides fast, economical and cost effective control, and delivers a clearly structured and easy-to-monitor system design that increases operational reliability. Compared to actuation by pilot valves in a central switching cabinet, control heads mounted directly on the actuator offer clear advantages in terms of planning, installation, start-up, maintenance and plant consistency. This is because the design is simplified and switching times for the process valves and the consumption of control air are minimised by the extremely short connections between the pilot valve in the control head and the pneumatic actuator.”
• Bürkert are represented in Ireland by Petrochem Pipeline Supply.
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