Solenoid valves for pressurised enclosure systems – for safe operation of control cabinets in ex areas
Learn more about collaboration with E.L.B. EX-Geräte Bachmann GmbH
Bürkert solenoid valves for use inside pressurised control cabinets:
- Increased process reliability: The pressure in the ex p housing is continuously monitored. An error message is generated if the value drops below or exceeds the minimum and maximum pressure respectively.
- Reliable operation: The solenoid valves are fail-safe. The overpressure in the control cabinet is maintained in the event of a voltage failure. In normal operation, they run without power, which helps to prevent additional heat development in the control cabinet.
- Simple installation: Opening and closing the terminal box only involves loosening one screw. It can also be rotated 90 degrees.
- Certified components: The solenoid valves are approved for use in explosion-protected plants not only throughout Europe, but also in Asia and Australia.
Many operators are faced with the problem of finding suitably approved components and control equipment when it comes to automating complex industrial plant in the potentially explosive atmosphere. In many cases, it is not possible to place control units such as large control cabinets in safe areas due to the distances involved – they need to be close to the process. Pressurised housings or control cabinets offer a solution that can meet the relevant ATEX requirements – a task for E.L.B. EX-Geräte Bachmann GmbH. In collaboration with Bürkert’s fluidics specialists, the solenoid valves used have undergone continuous optimisation until a perfect match with the operating conditions has been reached.
Over-pressure encapsulation systems enable use in potentially explosive atmospheres
Over-pressure encapsulation systems (ex p) are a practical explosion protection method which is suitable for devices that are not approved for use in potentially explosive environments. After installation in an over-pressure encapsulation housing in accordance with IEC 60079-2, these can then be used directly in the ex area.
To prevent the ingress of a potentially explosive atmosphere into the housing, a protective gas such as air or an inert gas is maintained at an overpressure inside the housing relative to the surrounding atmosphere. With the ex p type of protection, the control and monitoring of overpressure in the control cabinet plays a crucial role in explosion protection and, therefore, in the safety of the overall plant. The valves used, which are responsible for supplying protective gas and simultaneously fulfilling two tasks, must also contribute to this: flushing the entire housing volume after opening the doors on the control cabinet – e.g. for maintenance work and maintaining the overpressure in the housing during operation in an ex atmosphere.
Bachmann has been working closely with Bürkert for over ten years. The solenoid valves applied as rinsing valves were continuously and optimally adjusted for use inside pressurised control cabinets.
Specifically adjustable gas amount
The type 6281 solenoid valves are the result of the close collaboration. They are equipped with ATEX-certified solenoid valve coils Type AC10.
Beneath the valve seat, there are two adjustable throttles. This means that the valve closes as soon as the rinsing process has been successfully completed. However, adjustable throttles allow the user to open the valve cluster to a defined degree and set it to the specific gas quantity required to maintain the overpressure in the control cabinet.
Safety functions for error-free operation
The pressure in the ex p housing is continuously monitored. If it drops below a minimum or exceeds a maximum level, a warning message is generated. The setting for the leakage value can then be changed accordingly.
A further advantage: The valves run without power during normal plant operation, i.e. they only need electrical energy during the rinsing process but not to maintain the overpressure – and this helps to prevent additional heat development in the control cabinet. The overpressure in the control cabinet is maintained in the event of a voltage failure because the mechanically set leakage value is retained. The solenoid valves are thus fail-safe. Even a defective valve will not trigger an interruption or fault in operation.
Terminal box for flexible installation and reduced effort
The previous terminal box of the ex solenoid coils has been completely redesigned. It is not only more compact, but can be rotated by 90 degrees by the user with the help of a specially developed tool. Thanks to this flexibility, the number of variants is reduced, which streamlines the order management and stock-keeping processes. A further advantage is that opening and closing the terminal box only involves loosening one screw instead of the four screws previously required.
“This saves an enormous amount of time and effort. After all, we install around 1.000 of these valves each year. The terminal box can be easily accessed, the cover can be easily opened, thus reducing the amount of effort required.”
Servo-assisted 2/2-way diaphragm valve
- Servo-assisted diaphragm with diameter of up to DN50
- Vibration-proof, central screwed coil system
- Damped design for quiet closing
- Energy-saving double coil technology with kick and drop variant
- Explosion-proof versions