Importance

Loading Importance Indicators...

Abstract

The monitor employs a sensing piston whose position is balanced by offsetting the pressure to be monitored on one side of the piston by a reference pressure of approximately equal magnitude on the other side of the piston. A balance valve on the sensing piston controls the rate of flow of the reference gas from a first chamber bounded on one side by the sensing piston, into a second chamber bounded on one side by a signal piston having a striker whose surface is positioned proximate to the outlet of a gas jet tube. The gas jet tube is connected to a sensing gas pressure source and pressure detector and will produce a pneumatic signal when the striker surface of the signal piston blocks the outlet of the jet tube. Pneumatic signals are produced by the gas jet tube in response to the reference gas being admitted from the first chamber to the second chamber through the balance valve, which occurs in response to a decrease in the pressure to be monitored with respect to the reference gas pressure which displaces the sensing piston, thereby actuating the balance valve. A regulating valve in an outlet port of the second chamber establishes a minimum threshold value for the magnitude of the rate of flow of the reference gas from the first chamber to the second chamber. Thus, small variations in the magnitude of the reference gas pressure in the first chamber due, for example, to variations in the supply pressure, will not cause the production of erroneous pneumatic signals by the gas jet tube.

Loading the Abstract Image...

First Claim