Abstract: A diaphragm valve has a body defining a fluid passageway and, in the wall of the body, an opening in communication with the fluid passageway. A diaphragm for controlling fluid flow through the passageway extends across the opening and its periphery is clamped between the body and a bonnet secured to the body. Around the opening in the body is a diaphragm seating formed by two flat surfaces inclined relative to each other so as to be divergent. The bonnet is also provided with a diaphragm seating which comprises two flat surfaces inclined relative to each other so as to converge at the bottom end of the bonnet. The diaphragm seating is such as to provide a straight-through fluid passageway which, at each end of the body, is of circular section, these sections being joined by an elliptical or substantially elliptical section.

Abstract: A diaphragm valve has a body defining a fluid passageway and, in the wall of the body, an opening in communication with the fluid passageway. A diaphragm for controlling fluid flow through the passageway extends across the opening and its periphery is clamped between the body and a bonnet secured to the body. Around the opening in the body is a diaphragm seating formed by two flat surfaces inclined relative to each other so as to be divergent. The bonnet is also provided with a diaphragm seating which comprises two flat surfaces inclined relative to each other so as to converge at the bottom end of the bonnet. The diaphragm seating is such as to provide a straight-through fluid passageway which, at each end of the body, is of circular section, these sections being joined by an elliptical or substantially elliptical section.This is a division of application Ser. No. 900,393, filed Apr. 26, 1978, now abandoned.