Abstract: An electrosurgical system includes an electrosurgical generator to which the active and return electrodes (18, 20) of an electrosurgical instrument (12) are connected. In use the electrodes are immersed in electrically-conductive fluid to complete a conduction path between them. The electrodes (18, 20) are located on a shaft (16) of the instrument which extends from a handle (14). The shaft is covered in a translucent flexible sheath (50) comprising a tube (60) having a large proximal opening (62) to enable insertion of the instrument within the sheath, and a narrower distal opening (64) through which the distal end of the instrument shaft projects, thereby to expose the active electrode (18) to the electrically-conductive fluid.

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.