(a) Minimum requirements. An AMS shall consist of sensors to monitor the mine atmosphere and instruments at a surface location designated by the operator to receive information from the monitoring sensors. Each AMS installed in accordance with Secs. 75.323(d)(1)(ii), 75.340(a)(2) and 75.362(f) shall do the following: - (1) Monitor for circuit continuity and sensor function, and identify at the designated surface location any activated or malfunctioning sensor.
- (2) Signal a designated surface location at the mine when any interruption of circuit continuity occurs or any sensor malfunctions.
- (3) Signal affected working sections and the designated surface location when-
- (i) The carbon monoxide concentration at any carbon monoxide sensor reaches 5 parts per million above the established ambient level for that area; or
- (ii) The methane concentration at any methane monitoring station exceeds the maximum allowable concentration as specified for that location in 75.323.
- (4) Activate alarms at a designated surface location and affected working sections when the carbon monoxide concentration at any carbon monoxide sensor reaches 10 parts per million above the established ambient level for the area or when the optical density of smoke at any smoke sensor reaches 0.05 per meter.
(b) Return splits. - (1) If used to monitor return air splits under 75.362(f), AMS sensors shall monitor the mine atmosphere for percentage of methane in each return split of air from each working section between the last working place, or longwall or shortwall face, ventilated by that air split and the junction of that return air split with another air split, seal, or worked-out area. If auxiliary fans and tubing are used, the sensor also shall be located outby the auxiliary fan discharge.
- (2) If used to monitor air splits under 75.323(d)(1)(ii), AMS sensors shall monitor the mine atmosphere at the following locations:
- (i) In the return air course opposite the section loading point or, if auxiliary fans and tubing are used, in the return air course outby the auxiliary fans and a point opposite the section loading point.
- (ii) Immediately inby the location where the split of air meets another split of air, or inby the location where the split of air is used to ventilate seals or worked-out areas.
(c) Electrical installations. If used to monitor the intake air ventilating underground transformer stations, battery charging stations, substations, rectifiers, or water pumps under 75.340(a)(2), at least one sensor shall be installed to monitor the mine atmosphere for carbon monoxide or smoke at least 50 feet and no more than 100 feet downstream in the direction of air flow.
(d) Signals and alarms. - (1) A person designated by the operator shall be at a surface location where the signals and alarms from the AMS can always be seen or heard while anyone is underground. This person shall have access to two-way communication with working sections and with other identifiable duty stations underground. A mine map showing the underground monitoring system shall be posted at the surface location.
- (2) If a signal from any AMS sensor is activated, the monitor producing the signal shall be identified, an examination shall be made to determine the cause of the activation, and appropriate action shall be taken.
(e) Sensors. - (1) Each carbon monoxide sensor shall be capable of detecting carbon monoxide in air at a level of <plus-minus>1 part per million throughout the operating range.
- (2) Each methane sensor shall be capable of detecting 1.0 percent methane in air with an accuracy of <plus-minus>0.2 percent methane.
- (3) Each smoke sensor shall be capable of detecting the optical density of smoke with an accuracy of <plus-minus>0.005 per meter.
(f) Testing and calibration. At least once every 31 days- - (1) Each carbon monoxide sensor shall be calibrated with a known concentration of carbon monoxide and air sufficient to activate an alarm;
- (2) Each smoke sensor shall be functionally tested;
- (3) Each methane sensor shall be calibrated with a known methane- air mixture; and
- (4) Each oxygen sensor shall be calibrated with air having a known oxygen concentration.
(g) Intrinsic Safety. Components of AMS installed in areas where permissible equipment is required shall be intrinsically safe.
(h) Recordkeeping. If a signal device or alarm is activated, a record shall be made of the date, time, type of sensor, and the reason for its activation. Also the maximum concentration detected at the sensor producing the signal shall be recorded.
(i) Retention period. Records shall be retained for at least 1 year at a surface location at the mine and made available for inspection by, authorized representatives of the Secretary, the State Mine Inspector and representatives of miners.
053-4 Wyo. Code R. § 75.351