DN200 FLEX is a liquid-sealed over- and under-pressure safety valve designed for the protection of biogas tanks, digesters and gas storage systems. It protects the tank structure and gas storage membrane against excessive overpressure and vacuum conditions.

The valve operates on a liquid-seal principle and acts as a safety device when defined pressure limits are reached. It is designed for pressure protection and is not intended to regulate the normal operating pressure of a biogas system.

The DN200 FLEX version provides a blow-off capacity of up to 1,250 m³/h at a pressure increase of 20 mm water column and an air intake capacity of up to 750 m³/h at a corresponding pressure reduction.

The standard factory settings are +3.5 mbar overpressure and −1.0 mbar vacuum. Response pressure can be adjusted by means of weight plates in increments of 0.5 mbar. According to the manufacturer documentation, adjustment is possible up to +5.0 mbar overpressure and −1.5 mbar vacuum. Changes to the factory settings must be coordinated with the manufacturer and must remain within the permissible pressure limits of the tank and membrane.

Manufactured from corrosion-resistant V4A stainless steel (1.4571), DN200 FLEX is suitable for demanding biogas applications. The unit is equipped with a DN 200 PN10 flange connection and can be supplied with connections for optional hot-water heating.

Technical Specifications

• Model: DN200 FLEX
• Type: Over- and under-pressure safety valve
• Application: Biogas tanks, digesters and gas storage systems
• Nominal size: DN 200
• Connection: DN 200 PN10
• Material: Stainless steel V4A / 1.4571
• Operating principle: Liquid-sealed
• Factory overpressure setting: +3.5 mbar
• Factory vacuum setting: −1.0 mbar
• Maximum documented adjustment: +5.0 / −1.5 mbar
• Adjustment increments: 0.5 mbar
• Blow-off capacity: up to 1,250 m³/h
• Air intake capacity: up to 750 m³/h
• Total weight with sealing liquid: approx. 116 kg
• Heating: Optional hot-water heating connections
• Installation position: upright valve body with side flange connection to the tank