Oscar A Singleton

US Patent:

50552694, Oct 8, 1991

Filed:

Mar 6, 1989

Appl. No.:

7/319745

Inventors:

Perry A. Palumbo - New Kensington PA
Oscar Singleton - Pittsburgh PA
Louis G. Gaetano - New Kensington PA

Assignee:

Bacharach, Inc - Pittsburgh PA

International Classification:

G01N 2716

US Classification:

422 96

Abstract:

A temperature limited catalytic gas detector includes a catalytic gas sensor in one branch of a Wheatstone bridge network. A power supply is connected through a voltage controlled regulator to the bridge network. An instrumentation amplifier measures electrical imbalances across the bridge network. A display is connected to the output of the instrumentation amplifier. The detector also includes a comparator which compares the output of the instrumentation amplifier with a predetermined limit signal and produces an output when the output of the instrumentation amplifier exceeds the limit voyage. The regulator is responsive to the output of the comparator to thereby reduce the power supply to the bridge network. The limit signal is equivalent to the output of the instrumentation amplifier when the gas sensor is at a particular high temperature. The arrangement prevents the gas sensor from operating at excessive operation temperatures.