Pneumatic indicator esp. for explosive gas mixtures in air - has flow sensor to eliminate hunting when resetting working point

摘要

Pneumatic indicator detects gas and vapour contents in the air, esp. explosive gas mixtures in work areas. A flow sensor has an inlet pipe connected by a first switch to control and test gas passages. The switch control input is connected to a function generator output, and an outlet pipe connected to a pressure comparator. The latter's second input is connected to a control pressure generator whose output is connected to an output relay and vacuum unit by a second switch also connected to the function generator. The vacuum unit is connected by an amplifier to a vacuum pump which communicates with the flow sensor.