OFR-93-82 Development Of A Continuous Methane Monitor

Andros Analyzers Incorporated has designed and built two prototype continuous methane monitors capable of being mounted on a mining machine'. These instruments were designed for in-mine safety use. The monitors incorporated an NDIR optical/electronic analyzer design in which the response to the sample gas (methane in air) was achieved by synchronous detection and measurement of the amplitude oscillations of the trasmitted energy from an infrared source caused by the pressure modulation of the sample gas within the optical cell. Zero and span stability were to be achieved by the amplitude modulating of the infra-red source and using detected signal to correct for optical/electronic system variation. This design effort was to simplify and reduce the cost of the major components while eliminating the need for daily calibration. This report is the final report on this effort.