There are two main types of dampers, Type GD-C (left) and Type GD-R (right).

GD-C

• Butterfly valve with robust damper housing made of stainless steel, material 1.4301 (AISI/SAE 304), the gastight design surpasses the tightness requirements of DIN 25 496
• Test groove according to DIN 1946-4 resp. KTA 3601 to proof the required leakage of seat of damper blade. This is to proof the leak free seat of the damper blade connect the test groove to the seal test device via fast acting coupling, positioned at the front side on the damper housing.
• Circular damper blade made of stainless steel, material 1.4301 (AISI/SAE 304)
• Transmission of force to damper blade for the opening- and/or closing process by means of outside positioned actuator and shaft. Gastight shaft transition through housing. Shaft sealing made of viton

GD-R

•  Robust damper housing made of stainless steel in gastight design according to the tightness requirements of DIN 25496.
• Seat plate made of stainless steel with a round opening and two circular sealing rings made from silicone rubber, designed as a test groove to test the required tightness of the damper seat. In order to test the leak free seat of the damper blade, the test groove can be connected to an appropriate seal test device via a fast acting coupling positioned outside the damper housing
• Circular damper blade made of stainless steel, conveyed by a kinematical lever system. The specially designed lever system made of stainless steel secures the damper blade’s end positions “Open” and “Close” by means of special toggle levers
• To protect the elastic and aging resistant seal, the opening of the damper blade starts with a parallel travel before turning into a rotating movement later
• Transmission of force to damper blade for the opening or closing process by means of external actuator, shaft and lever system. Gastight shaft transition through housing. 

Electrical-, pneumatic- or manual actuator are available on both type GD-C and GD-R. Emergency actuating by means of hand wheel.

Prior to dispatch, both Krantz GD-C & GD-R bubble tight valves/dampers are tested for gas-tightness according to DIN 25496 standard. The tightness test can be carried out on site via the built-in fast acting coupling on each damper.

The valves are specifically designed to be used in nuclear facilities, pharmacuetical laboratories, military and civil air shelters, oil refineries and BSL 3 & 4 laboratories. In Hong Kong, over 640 dampers have been installed and are in operation.