Section 75.351 - Atmospheric monitoring systems(a)AMS operation. Whenever personnel are underground and an AMS is used to fulfill the requirements of §§ 75.323(d)(1)(ii) , 75.340(a)(1)(ii) , 75.340(a)(2)(ii) , 75.350(b) , 75.350(d) , or 75.362(f) , the AMS must be operating and a designated AMS operator must be on duty at a location on the surface of the mine where audible and visual signals from the AMS must be seen or heard and the AMS operator can promptly respond to these signals.(b)Designated surface location and AMS operator. When an AMS is used to comply with §§ 75.323(d)(1)(ii) , 75.340(a)(1)(ii) , 75.340(a)(2)(ii) , 75.350(b) , 75.350(d) , or 75.362(f) , the following requirements apply: (1) The mine operator must designate a surface location at the mine where signals from the AMS will be received and two-way voice communication is maintained with each working section, with areas where mechanized mining equipment is being installed or removed, and with other areas designated in the approved emergency evacuation and firefighting program of instruction (§ 75.1502 ).(2) The mine operator must designate an AMS operator to monitor and promptly respond to all AMS signals. The AMS operator must have as a primary duty the responsibility to monitor the malfunction, alert and alarm signals of the AMS, and to notify appropriate personnel of these signals. In the event of an emergency, the sole responsibility of the AMS operator shall be to respond to the emergency.(3) A map or schematic must be provided at the designated surface location that shows the locations and type of AMS sensor at each location, and the intended air flow direction at these locations. This map or schematic must be updated within 24 hours of any change in this information.(4) The names of the designated AMS operators and other appropriate personnel, including the designated person responsible for initiating an emergency mine evacuation under § 75.1501 , and the method to contact these persons, must be provided at the designated surface location.(c)Minimum operating requirements. AMSs used to comply with §§ 75.323(d)(1)(ii) , 75.340(a)(1)(ii) , 75.340(a)(2)(ii) , 75.350(b) , 75.350(d) , or 75.362(f) must: (1) Automatically provide visual and audible signals at the designated surface location for any interruption of circuit continuity and any electrical malfunction of the system. These signals must be of sufficient magnitude to be seen or heard by the AMS operator.(2) Automatically provide visual and audible signals at the designated surface location when the carbon monoxide concentration or methane concentration at any sensor reaches the alert level as specified in § 75.351(i) . These signals must be of sufficient magnitude to be seen or heard by the AMS operator.(3) Automatically provide visual and audible signals at the designated surface location distinguishable from alert signals when the carbon monoxide, smoke, or methane concentration at any sensor reaches the alarm level as specified in § 75.351(i) . These signals must be of sufficient magnitude to be seen or heard by the AMS operator.(4) Automatically provide visual and audible signals at all affected working sections and at all affected areas where mechanized mining equipment is being installed or removed when the carbon monoxide, smoke, or methane concentration at any sensor reaches the alarm level as specified in § 75.351(i) . These signals must be of sufficient magnitude to be seen or heard by miners working at these locations. Methane signals must be distinguishable from other signals.(5) Automatically provide visual and audible signals at other locations as specified in Mine Emergency Evacuation and Firefighting Program of Instruction (§ 75.1502 ) when the carbon monoxide, smoke, or methane concentration at any sensor reaches the alarm level as specified in § 75.351(i) . These signals must be seen or heard by miners working at these locations. Methane alarms must be distinguishable from other signals.(6) Identify at the designated surface location the operational status of all sensors.(7) Automatically provide visual and audible alarm signals at the designated surface location, at all affected working sections, and at all affected areas where mechanized mining equipment is being installed or removed when the carbon monoxide level at any two consecutive sensors alert at the same time. These signals must be seen or heard by the AMS operator and miners working at these locations.(d)Location and installation of AMS sensors.(1) All AMS sensors, as specified in §§ 75.351(e) through 75.351(h) , must be located such that measurements are representative of the mine atmosphere in these locations.(2) Carbon monoxide or smoke sensors must be installed near the center in the upper third of the entry, in a location that does not expose personnel working on the system to unsafe conditions. Sensors must not be located in abnormally high areas or in other locations where air flow patterns do not permit products of combustion to be carried to the sensors.(3) Methane sensors must be installed near the center of the entry, at least 12 inches from the roof, ribs, and floor, in a location that would not expose personnel working on the system to unsafe conditions.(e)Location of sensors-belt air course.(1) In addition to the requirements of paragraph (d) of this section, any AMS used to monitor belt air courses under § 75.350(b) must have approved sensors to monitor for carbon monoxide at the following locations:(i) At or near the working section belt tailpiece in the air stream ventilating the belt entry. In longwall mining systems the sensor must be located upwind in the belt entry at a distance no greater than 150 feet from the mixing point where intake air is mixed with the belt air at or near the tailpiece;(ii) No more than 50 feet upwind from the point where the belt air course is combined with another air course or splits into multiple air courses;(iii) At intervals not to exceed 1,000 feet along each belt entry. However, in areas along each belt entry where air velocities are between 50 and 100 feet per minute, spacing of sensors must not exceed 500 feet. In areas along each belt entry where air velocities are less than 50 feet per minute, the sensor spacing must not exceed 350 feet;(iv) Not more than 100 feet downwind of each belt drive unit, each tailpiece, transfer point, and each belt take-up. If the belt drive, tailpiece, and/or take-up for a single transfer point are installed together in the same air course, and the distance between the units is less than 100 feet, they may be monitored with one sensor downwind of the last component. If the distance between the units exceeds 100 feet, additional sensors are required downwind of each belt drive unit, each tailpiece, transfer point, and each belt take-up; and(v) At other locations in any entry that is part of the belt air course as required and specified in the mine ventilation plan.(2) Smoke sensors must be installed to monitor the belt entry under § 75.350(b) at the following locations:(i) At or near the working section belt tailpiece in the air stream ventilating the belt entry. In longwall mining systems the sensor must be located upwind in the belt entry at a distance no greater than 150 feet from the mixing point where intake air is mixed with the belt air at or near the tailpiece;(ii) Not more than 100 feet downwind of each belt drive unit, each tailpiece transfer point, and each belt take-up. If the belt drive, tailpiece, and/or take-up for a single transfer point are installed together in the same air course, and the distance between the units is less than 100 feet, they may be monitored with one sensor downwind of the last component. If the distance between the units exceeds 100 feet, additional sensors are required downwind of each belt drive unit, each tailpiece, transfer point, and each belt take-up; and(iii) At intervals not to exceed 3,000 feet along each belt entry.(iv) This provision shall be effective one year after the Secretary has determined that a smoke sensor is available to reliably detect fire in underground coal mines.(f)Locations of sensors-the primary escapeway. When used to monitor the primary escapeway under § 75.350(b)(4) , carbon monoxide or smoke sensors must be located in the primary escapeway within 500 feet of the working section and areas where mechanized mining equipment is being installed or removed. In addition, another sensor must be located within 500 feet inby the beginning of the panel. The point-feed sensor required by § 75.350(d)(1) may be used as the sensor at the beginning of the panel if it is located within 500 feet inby the beginning of the panel.(g)Location of sensors-return air splits.(1) If used to monitor return air splits under § 75.362(f) , a methane sensor must be installed in the return air split between the last working place, longwall or shortwall face ventilated by that air split, and the junction of the return air split with another air split, seal, or worked out area.(2) If used to monitor a return air split under § 75.323(d)(1)(ii) , the methane sensors must be installed at the following locations: (i) In the return air course opposite the section loading point, or, if exhausting auxiliary fan(s) are used, in the return air course no closer than 300 feet downwind from the fan exhaust and at a point opposite or immediately outby the section loading point; and(ii) Immediately upwind from the location where the return air split meets another air split or immediately upwind of the location where an air split is used to ventilate seals or worked-out areas.(h)Location of sensors-electrical installations. When monitoring the intake air ventilating underground transformer stations, battery charging stations, substations, rectifiers, or water pumps under § 75.340(a)(1)(ii) or § 75.340(a)(2)(ii) , at least one sensor must be installed to monitor the mine atmosphere for carbon monoxide or smoke, located downwind and not greater than 50 feet from the electrical installation being monitored.(i)Establishing alert and alarm levels. An AMS installed in accordance with the following paragraphs must initiate alert and alarm signals at the specified levels, as indicated: (1) For § 75.323(d)(1)(ii) alarm at 1.5% methane.(2) For §§ 75.340(a)(1)(ii) , 75.340(a)(2)(ii) , 75.350(b) , and 75.350(d) , alert at 5 ppm carbon monoxide above the ambient level and alarm at 10 ppm carbon monoxide above the ambient level when carbon monoxide sensors are used; and alarm at a smoke optical density of 0.022 per meter when smoke sensors are used. Reduced alert and alarm settings approved by the district manager may be required for carbon monoxide sensors identified in the mine ventilation plan, § 75.371(nn) .(3) For § 75.362(f) , alert at 1.0% methane and alarm at 1.5% methane.(j)Establishing carbon monoxide ambient levels. Carbon monoxide ambient levels and the means to determine these levels must be approved in the mine ventilation plan (§ 75.371(hh) ) for monitors installed in accordance with §§ 75.340(a)(1)(ii) , 75.340(a)(2)(ii) , 75.350(b) , and 75.350(d) .(k)Installation and maintenance. An AMS installed in accordance with §§ 75.323(d)(1)(ii) , 75.340(a)(1)(ii) , 75.340(a)(2)(ii) , 75.350(b) , 75.350(d) , or 75.362(f) must be installed and maintained by personnel trained in the installation and maintenance of the system. The system must be maintained in proper operating condition.(l)Sensors. Sensors used to monitor for carbon monoxide, methane, and smoke must be either of a type listed and installed in accordance with the recommendations of a nationally recognized testing laboratory approved by the Secretary; or these sensors must be of a type, and installed in a manner, approved by the Secretary.(m)Time delays. When a demonstrated need exists, time delays may be incorporated into the AMS. These time delays must only be used to account for non-fire related carbon monoxide alert and alarm sensor signals. These time delays are limited to no more than three minutes. The use and length of any time delays, or other techniques or methods which eliminate or reduce the need for time delays, must be specified and approved in the mine ventilation plan.(n)Examination, testing, and calibration.(1) At least once each shift when belts are operated as part of a production shift, sensors used to detect carbon monoxide or smoke in accordance with §§ 75.350(b) , and 75.350(d) , and alarms installed in accordance with § 75.350(b) must be visually examined.(2) At least once every seven days, alarms for AMS installed in accordance with §§ 75.350(b) , and 75.350(d) must be functionally tested for proper operation.(3) At intervals not to exceed 31 days- (i) Each carbon monoxide sensor installed in accordance with §§ 75.340(a)(1)(ii) , 75.340(a)(2)(ii) , 75.350(b) , or 75.350(d) must be calibrated in accordance with the manufacturer's calibration specifications. Calibration must be done with a known concentration of carbon monoxide in air sufficient to activate the alarm;(ii) Each smoke sensor installed in accordance with §§ 75.340(a)(1)(ii) , 75.340(a)(2)(ii) , 75.350(b) , or 75.350(d) must be functionally tested in accordance with the manufacturer's calibration specifications;(iii) Each methane sensor installed in accordance with §§ 75.323(d)(1)(ii) or 75.362(f) must be calibrated in accordance with the manufacturer's calibration specifications. Calibration must be done with a known concentration of methane in air sufficient to activate an alarm.(iv) If the alert or alarm signals will be activated during calibration of sensors, the AMS operator must be notified prior to and upon completion of calibration. The AMS operator must notify miners on affected working sections, areas where mechanized mining equipment is being installed or removed, or other areas designated in the approved emergency evacuation and firefighting program of instruction (§ 75.1502 ) when calibration will activate alarms and when calibration is completed.(4) Gases used for the testing and calibration of AMS sensors must be traceable to the National Institute of Standards and Technology reference standard for the specific gas. When these reference standards are not available for a specific gas, calibration gases must be traceable to an analytical standard which is prepared using a method traceable to the National Institute of Standards and Technology. Calibration gases must be within ±2.0 percent of the indicated gas concentration.(o)Recordkeeping.(1) When an AMS is used to comply with §§ 75.323(d)(1)(ii) , 75.340(a)(1)(ii) , 75.340(a)(2)(ii) , 75.350(b) , 75.350(d) , or 75.362(f) , individuals designated by the operator must make the following records by the end of the shift in which the following event(s) occur: (i) If an alert or alarm signal occurs, a record of the date, time, location and type of sensor, and the cause for the activation.(ii) If an AMS malfunctions, a record of the date, the extent and cause of the malfunction, and the corrective action taken to return the system to proper operation.(iii) A record of the seven-day tests of alert and alarm signals; calibrations; and maintenance of the AMS must be made by the person(s) performing these actions.(2) The person entering the record must include their name, date, and signature in the record.(3) The records required by this section must be kept either in a secure book that is not susceptible to alteration, or electronically in a computer system that is secure and not susceptible to alteration. These records must be maintained separately from other records and identifiable by a title, such as the 'AMS log.'(p)Retention period. Records must be retained for at least one year at a surface location at the mine and made available for inspection by miners and authorized representatives of the Secretary.(q)Training.(1) All AMS operators must be trained annually in the proper operation of the AMS. This training must include the following subjects:(i) Familiarity with underground mining systems;(ii) Basic atmospheric monitoring system requirements;(iii) The mine emergency evacuation and firefighting program of instruction;(iv) The mine ventilation system including planned air directions;(v) Appropriate response to alert, alarm and malfunction signals;(vi) Use of mine communication systems including emergency notification procedures; and(vii) AMS recordkeeping requirements.(2) At least once every six months, all AMS operators must travel to all working sections.(3) A record of the content of training, the person conducting the training, and the date the training was conducted, must be maintained at the mine for at least one year by the mine operator.(r)Communications. When an AMS is used to comply with § 75.350(b) , a two-way voice communication system required by § 75.1600 must be installed in an entry that is separate from the entry in which the AMS is installed no later than August 2, 2004. The two-way voice communication system may be installed in the entry where the intake sensors required by §§ 75.350(b)(4) or 75.350(d)(1) are installed. 69 FR 17527 , Apr. 2, 2004, as amended at 73 FR 80612 , Dec. 31, 2008