Burkert's new Type 8681 control head offers the key advantage of universal fitment onto third-party hygienic valves: single seat valves, double seat, mix proof, and also quarter turn ball and butterfly valves that have linear stainless steel actuators. The 8681 comes complete with a full range of communication networks, such as ASi and DeviceNet, and is enclosed in a robust polycarbonate and polyamide housing that is IP65 and IP67 rated, enabling it to be washed down and cleaned safely.
The Type 8681 is ideal for applications on valves used in the hygienic processing industries; typically food and beverage, breweries, dairies, pharmaceutical and personal healthcare. In these application sectors the 8681 cuts costs for users, by virtue of its ability to be fitted to any manufacturer's valves. It has a range of adapters that allows it to be fitted to any actuator currently on the market.
The 8681 control heads are also designed to be used with decentralised automation systems using ASi or Fieldbus communications. They can be used on most process valves, delivering the required standardisation across hygienic processing sites and offering control and diagnostic safety, thanks to remote visualisation of the positions of the respective valves. The 8681 units execute all pneumatic commands, position feedback functions and diagnostics and, depending upon the process valve, can control up to three pneumatic chambers separately.
After installing the control head on the valve actuator, the positions of the valve are determined automatically by a fast, reliable “teach-in” function, which eliminates any need for configuration and manual adjustments
In addition to their decentralised control benefits, the 8681 control heads offer the advantage of ease of installation and checking. The control head verifies the respective positions of the process valve via an inductive analogue position sensor. After installing the control head on the valve actuator, the positions of the valve are determined automatically by a fast, reliable “teach-in” function, which eliminates any need for configuration and manual adjustments. In addition, an AUTOTUNE function reduces start-up times by means of simple self-setting limit switches.
In operation, the series 8681 control head provides maximum integrity with IP65/67 ingress protection; and by routing some of the exhausted control air to give a slight overpressure inside the head, it also prevents condensation from forming internally. The 8681 enables instant visual diagnostics of valve status by an ultra-bright LED with colour coding (Open/Closed/Error) that can be seen from up to 100 metres away.
Complementing the instant visual diagnostics facility, a large format, visual, luminous colour display unit signals valve positions, operating errors, anomalies in communication with the bus, and mechanical blockages in the valves (et al). Internal diagnostic data, such as the number of cycles achieved for servicing of the valve seals, or operating errors, are archived in the memory of the control head, where they can be read in detail via a service interface using Bluetooth for a SmartPhone and a USB interface for PCs.
Also aiding operational flexibility of the Type 8681 is a feature that allows the switching speed of each driver chamber to be set individually for both directions of movement: this is achieved 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 manual override lever. A patented magnetically coded key allows switching of the main actuator from outside a completely enclosed device, ensuring full IP protection also during maintenance on the process valves.
Compared with 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 and maintenance
"Decentralised automation of process valves using the 8681 universal control head delivers cost savings through plant standardisation, providing fast, economical and safe control,” said Ian Webster, Field Segment Manager, Hygienic Processing, for Burkert UK. “Decentralisation also delivers a clearly structured and easy-to-monitor system design that increases operational reliability.
“Compared with 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 and maintenance.
“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.”