Beard's Small Regulator
Date of manufacture:
This is the forerunner of the Adams valve. It is a single stage preset pressure regulator. The preset tensioning spring bears upon the disc that forms the end of the bellows-style diaphragm, tending to depress it. The lazy tongs mechanism reverses the direction of the action so that the actuator plate is permitted to lift , opening the valve and admitting gas to enter the bellows. The increase in pressure below the bellows disc tends to reverse the opening action and the valve closes. The reduced, regulated pressure is controlled by the force of the spring and thus remains constant depite the fall of pressure within the cylinder. Note that the outlet is a nozzle to which rubber tubing was applied indicating that the outlet pressure must have been below 5 lb/sq in.(1 bar).
Macintosh Mushin & Epstein 'Physics for the Anaesthetist', 3rd Edn. 1963, Blackwell