New control head for process valves
Bürkert rounds out its product line for decentral automation of process fittings
The 8681 control head was specially developed for decentral automation of hygienic seat valves, butterfly valves and ball valves. It supplements the Bürkert ELEMENT series of control heads, digital positioners and process controllers for diaphragm, angle seat and globe valves and rounds out the automation portfolio for the food/beverage and pharmaceutical industries.
With the 8681 Bürkert presents a new control head which has been specially optimized for decentral automation of pneumatically controlled hygienic process valves. It is universally adaptable and can be combined with all commercially available valve types, such as butterfly valves, ball valves and single and double-seat valves. Since the control head is very easy to clean, features time-tested IP protection and is made of chemical-resistant materials, it is ideal for use in hygienic applications. Within the framework of decentral automation concepts the 8681, as a central unit, performs all pneumatic actuation, feedback and diagnostic functions, as well as bus communication. Depending on the process valve, as many as three pneumatic actuator chambers can be controlled separately.
Easy installation, operation and status control
The respective switching positions of the process valve are measured by the control head via an inductive analog position sensor and transmitted to a PLC. After installation of the control head on the valve actuator the switching positions are automatically determined by a fast and reliable teach-in function, which eliminates the need for manual configuration. A fourth switching position can be read in by an externally mounted inductive proximity switch.
The switching speed of each driver chamber can be set individually for both directions of movement by means of a restrictor function integrated in the pilot valve. In addition, a non-return valve prevents faulty switching of the process valves due to back pressure. Independent of the power supply, each pilot valve can be switched manually by means of a mechanical hand control. The patented magnetically coded manual control allows switching of the main actuator from outside a completely enclosed device – ensuring full IP protection also during maintenance on the process valve.
In addition to the electric feedback to the 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.
Decentral automation of process valves: fast, economical and reliable
Compared with actuation by pilot valves in a central switch cabinet, control heads mounted directly on the actuator offer clear advantages in terms of planning, installation, start-up and maintenance due to the significant reduction of the required connections. The switching times for the process fittings and the consumption of control air are minimized by the extremely short hoses between the pilot valve in the control head and the pneumatic actuator. The decentral automation concept allows a clearly structured and easy-to-monitor system design, which will increase operational reliability.
Facts and data
- Pneumatic module for 0…3 pilot valves, 200 l/min, restrictable and integrated non-return valve
- Feedback function via inductive position sensor for monitoring strokes up to 85 mm; 3 positions configurable via teach-in function; connection for external proximity switch
- Three-colour visual status display (green/yellow/red) with high-power LEDs
- Electrical supply via AS interface; without communication 12…28 VDC
- Electrical connection via cable gland or M12 plug connectors
- Fluidic connection G1/4” VA, G1/8” VA working connections
- Protection type IP65 and IP67 combined
- Approved for ATEX Cat. 3, Zone 2/22