Abstract: A valve housing of a diaphragm valve has a first valve chamber, into which open a central channel and first and second channels. Valve seats are arranged in the housing, and a first diaphragm is adapted to seal against at least one of the first and second valve seats. A second valve chamber, into which opens a fourth channel, communicates with the central channel through an opening in the housing. A third valve seat is provided and a second diaphragm is adapted to seal the third valve seat.

Abstract: A diaphragm valve for controlling a flow of gaseous or liquid fluid and including a valve housing having a valve chamber, into which opens a central channel and on each side thereof a first side channel and a second side channel, respectively, each having an external connection for fluid, valve seats arranged in the housing, an elastic diaphragm adapted to be brought into and away from sealing contact with at least one of the valve seats and controls for actuating the diaphragm. At least one portion of each valve seat is common to the central channel and one of the side channels. Two controls are arranged to press the diaphragm against one such portion each, thereby to shut off the passage of fluid between the central channel and the respective side channel, and to raise one portion each of the diaphragm off the respective portion of the valve seat thereby to open passage of flow between the central channel and the respective side channel.