Endurance regulator - cut away
Date of manufacture:
This regulator has a bull-nose fitting. There is an over-pressure relief valve to the right of the photograph (and schematic). There is a large diaphragm that separates gas at regulated pressure from atmospheric air. The diaphragm is directly connected to the valve seating. The tension of the spring on the left of the picture, acts together with atmospheric pressure on one side of the diaphragm and tends to open the valve mechanism while the regulated pressure impinges upon the other side of the diaphragm, tending to close it. There is no lazy-tongs mechanism to apply leverage as with the Adams Valve. The needle valve at top controls the output flow. It encounters only constant, regulated pressure and therefore delivers a very nearly constant flow.
Macintosh Mushin & Epstein 'Physics for the Anaesthetist', 3rd Edn. 1963, Blackwell