METHANE ALARM Russian patent published in 1999 - IPC

FIELD: aids monitoring mine atmosphere, devices warning on maximum permissible concentration of methane in atmosphere. SUBSTANCE: methane alarm has bridge measurement circuit, DC meter, analog-to-digital converter, arithmetic-logic device, storage and storage battery. Output of digital-to-analog converter is linked to input of DC amplifier whose output is connected to input of bridge measurement circuit and first input of analog commutator. Output of bridge measurement circuit and storage battery are connected correspondingly to second and third inputs of analog commutator. Output of analog commutator is connected to input of analog-to-digital converter which output is linked to first input of arithmetic-logic device whose first, second, third and fourth outputs are connected correspondingly to input of digital-to-analog converter, input of indicator of threshold level, fourth input of analog commutator and input of storage. Second input of arithmetic-logic device is connected to output of storage. Digital processing of signals makes it feasible to increase measurement accuracy and to simplify procedure of adjustment and tuning. EFFECT: increased measurement accuracy, simplified procedure of adjustment and tuning. 1 dwg