Pressure switch for controlling pressure regulator - has two photocells operated by shutter on pointer connected to Bourdon tube to prevent excessive pressure rise by closing magnetic valve

摘要

The pressure switch for use in pressure regulators consists of a standard manometer mechanism using a Bourdon tube (c) and central spindle (g) carrying a pointer (h). On the underside of the pointer is a shutter (jj) which can pass through the light beam to a photo-electric detector (p)(q). This detector is mounted on a platform whose position can be adjusted from outside by means of a friction drive (1)(t) so that a signal is available when the pointer reaches some predetermined limit. The pointer also has a striker (j) which operates a second, spring-loaded shutter (c). If the pressure in the system rises above the value set, the striker moves the first shutter beyond a slot in the second shutter so that a second photo-electric detector is energised. The signal from this operates a magnetic valve to reduce the pressure.