Overpressure and underpressure protection

To make biogas plant operation as safe as possible, we have designed and built our Biosecure overpressure/underpressure protection system in accordance with the most stringent safety requirements and after careful selection of the relevant harmonised standards and other technical specifications. Thus, it meets the current state of the art and guarantees a maximum level of safety.

The Biosecure can either be controlled mechanically through a biogas storage membrane or using weight-operated immersion cups. The Biosecure housing is made of stainless steel; the immersion cups and the steering linkage are plastic. We use water as sealing liquid to which antifreeze is added at low outside temperatures. As an option, an insulating jacket or an electric heating rod can be installed to prevent the water from freezing when no antifreeze is added. The functioning inside the housing can be checked through the built-in sight glass.

Über- und Unterdrucksicherung Funktionsweise

The Biosecure overpressure/underpressure protection monitors and regulates the positive and negative pressure in biogas digesters. It protects the biogas storage membranes of digesters, post-digesters and digestate storage tanks against inadmissible loads.
The Biosecure has been designed as a safety component in the sense of the 2006/42/EC Machinery Directive.

However, the safety we intent to achieve when operating a biogas plant can only be accomplished in practice if all necessary measures are taken. It falls within the operator’s duty of care to support these measures and to check their execution.

biogas plant components biogastechnik süd



  • reliable overpressure protection: functions either pneumatically (under-overpressure) or controlled mechanically (e.g. gas bag)
  • in connection with the insulating jacket, no antifreeze necessary as barrier liquid down to -20 °C
  • no replenishing of the barrier liquid necessary
  • auto-regulation of fill levels
  • excess condensate drains into the digester
  • maintenance-free
  • a heating rod optionally available
  • includes a pressure test port
  • includes a pressure sensor terminal

Extension option for overpressure and underpressure protection

Accessories (optional)

- pipe connection kit for substrate pipes
- pipe connection kit for heating

Do you need more information about overpressure and underpressure protection?

Download technical information here or call us!