Safety quick-closing butterfly flap valves are an integral part of the containment. The butterfly flap valves are used in the ventilation system (HVAC) of the containment in nuclear plants. In case of an emergency, like "LOCA - Lost of cooling accident“ the butterfly flap valve shut-off quick and safe. The butterfly flap valve is also absolutely tight under earthquake conditions. The KÜHME safety quick closing butterfly flap valve is a benchmark for this application.

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Application areas

  • Automatic butterfly flap valve in nuclear plants, designed and made in accordance with the standards developed by the Nuclear Commission KTA, and acc. to specification KS D2021
Nominal size: DN 200 to 1000
Operating pressure: max. 7.0 bar g
Differential pressure switchable: up to 0.1 bar
Operating temperature: max. + 180°C


  • Closing time < 3 seconds
  • Safety due to the proven tightness system meeting the tightness requirement of a leakage rate of
    0.5 l/h at 20 mbar g
  • Closing of the valve is dampened to reduce pressure surges in the pipeline
  • Double seat - one valve instead of two separate valves - compact and cost-efficient solution

  • Convenient automatic testing of the sealing system during plant operation - without having to dismantle the valve
  • Heavy duty design for high amount of operating cycles
  • High-performance valve with a long service life

The quick-closing flap is operated by a pneumatic actuator with a solenoid valve. Automatic quick-closing relieves the pressure volume in the pneumatic actuator via the quick-exhaust valve. Closing springs laterally attached to the actuator close the flap. As the result of the lever kinematics the flap blade move in parallel - and thus in a wear-optimised manner - into the sealing seat.

Technical features

Valve body: Welded steel construction with test connection at the containment flange
Seat sealing system: Soft-sealing, concentric double valve seats made of stainless steel, with integrated intermediate ventilation
Shaft sealing: Double O-ring sealing system with test connection
Actuator type: Pneumatic KÜHME piston actuator for the stroke movement, reset to “closed” by flap position spring force, piloted by an electro-pneumatic solenoid valve
Process connection: Flange connection, available in DIN or ANSI design
Special features:
  • Coating: Special nickel plating, can be decontaminated
  • Safety class C/2
  • Closing time: 90% less than 1 second, remaining 10% within 2 seconds
  • Hydraulic damping of the end position reduces the stress on the seal during closing and prevents pressure surges in the pipeline.
  • Dynamic stress test (Institute of Aerodynamics, RWTH Aachen University)
  • Reliability tests with 20,000 cycles (TÜV Bayern)
  • Earthquake test with 3 axes (Industrieanlagen-Betriebsgesellschaft / Airbus Industries)
  • Valve optionally with vacuum device for leaking media (incl. distribution and shut-off valve)
  • Optionally available with electrical actuator
  • Flange connection to containment with double o-ring for tightness testing