VOLUME V - COAL MINES
75.1103-6 Automatic Fire Sensors; Actuation of Fire-Suppression Systems
The fire sensor and suppression devices required at belt drives under Section 75.1101 may be separate and apart from the sensor and alarm system required under Section 75.1103, except that the sensor and alarm system required under Section 75.1103 shall transverse and include the belt drive area. If the systems required under Sections 75.1101 and 75.1103 are combined and are interconnected, then the more stringent requirements of Section 75.1103-7(b) shall apply. For example, if the sensor and alarm system under Section 75.1103 is intrinsically safe, then interconnected fire-suppression devices under Section 75.1101 shall also be intrinsically safe.
75.1103-7 Electric Components; Permissibility
In order for the sensor and alarm system to remain functional as required by Section 75.1103-4(e), the source of power can be the line side of the circuit breaker or other protective device normally used to stop the belt. When battery-powered systems are used to comply with this section, a relay may be used to disconnect the battery power supply. A manually-operated on/off switch actuated by a miner as he leaves the section is not acceptable.
75.1103-9 Minimum Requirements; Fire Suppression
Materials and Location; Maintenance of Entries and Crosscuts; Access Doors; Communications;
Fire Crews; High-expansion Foam Devices
One supply of materials required by paragraph (a) of this Section will suffice for two belt drives, provided the supply is located within 300 feet of each drive unit and the ventilating current in both belt drive entries travels in a direction opposite that of the normal movement of the belts.
"Five hundred feet of fire hose" required by paragraph (a)(1) of this Section may be satisfied by the same fire hose required by Section 75.1100-2(b) or (c) if such hose is within 300 feet of the belt drive or tailpiece, as applicable.
The fire suppression required by paragraphs (a)(2) and (d) of this Section may be an extension of the system required by Section 75.1101 or a separate system installed at the belt "discharge head." In either case, the fire suppression system need cover only the belt discharge head in addition to that area now protected by the requirements of Section 75.1101.
"A crew consisting of at least five members" as used in paragraph (e) of this Section means any five men within the mine during the same working shift.
75.1103-11 Test of Fire Hydrants and Fire Hose; Record of Tests
Fire hose shall be tested annually to ensure that the hose and couplings are serviceable. The test shall include unreeling and reloading all of the fire hose at each depot and flowing water through hose with a nozzle attached. The nozzle, if adjustable, shall be opened and closed quickly to introduce shock to the system. When the fire hose is made up of sections, at least one section shall be so tested each year, and a record kept of the date, the pressure used, and the fire hose section tested. A different section of hose shall be tested each year. However, if the fire hose consists of more than five sections, then all of the sections shall be tested at least once during the 5-year period. In addition, if any water leakage occurs during a test, then all of the hose at the depot shall be tested, and all leaking hose and/or couplings replaced immediately. It shall not be necessary to dry the hose following a test. The outer surface of the hose shall be kept reasonably clean. In no instance shall a fire hose be tested with compressed air.
75.1104 Underground Storage, Lubricating Oil and Grease
Portable, closed metal containers are considered to be of fireproof construction for temporary storage of lubricating oil and grease in face regions and other underground working places. Small vessels should be of the "safety can" type approved by the National Fire Protection Association. However, small metal containers, such as 5-gallon metal containers with plastic pouring spouts or lids are acceptable. No additional storage container is required for grease gun cartridges stored in face regions and other underground working places, provided they are kept in their shipping containers.
Underground storage places for lubricating oil and grease shall be of fire-proof construction in that all sides, roof, and floor must be composed of incombustible material. Concrete, concrete block, cinder block, or plastered wire-mesh fastened on substantial framework (or equivalent) are acceptable. The framework should be metal; however, flame-retardant wood, bearing the Underwriter's Laboratories, Inc., seal may be used also. The floor should preferably be concrete to facilitate removal of spillage. Loose floor material such as sand, cinders, or limestone dust will absorb spilled oil and grease and become flammable.
The storage of emulsion-type fire-resistant hydraulic oils needs special consideration. The water in some emulsion-type oils may evaporate from spilled pools leaving the residue which is highly flammable. Where spillage in storage areas is a factor, the emulsion-type hydraulic oils should be considered as flammable.
Synthetic-ester and similar fire-resistant hydraulic oils remain fire retardant after spillage.
75.1106 Welding, Cutting, or Soldering with Arc or
This standard requires, among other precautions, that work be done under the supervision of a qualified person and that testing for methane be conducted immediately before and continuously during cutting, welding, and soldering operations. The tests for methane must be made in locations where methane is likely to exist, and in no case is cutting, welding, or soldering permitted in an atmosphere that contains 1.0 percent or more methane.
A person will be considered qualified for testing for methane and for oxygen deficiency if: 1) the person has been qualified for this purpose in the State in which the mine is located, or 2) the person has been qualified for this purpose by the Secretary. Not-withstanding the provisions of 1) and 2), no person shall be a qualified person for testing for methane unless the person demonstrates to the satisfaction of an authorized representative of the Secretary that he or she is qualified to test for methane with a portable methane detector approved by MSHA.
"Continuously" as used in this section is interpreted to mean that a qualified person is to remain at the worksite, and tests for methane must be made at regular and frequent intervals. In mines where welding, cutting, or soldering with a flame is performed, the inspector should observe at least one such operation to determine if the frequency of such tests is sufficient to ensure a systematic and effective means of monitoring the methane content in the air in the vicinity of the worksite.
Methane tests are critical for safe cutting, welding or soldering in an underground coal mine and are somewhat different from methane tests used for general mine ventilation. While § 75.323(a) specifies that tests for methane concentrations must be made at least 12 inches from the roof, face, ribs and floor, this distance requirement is not applicable to welding, cutting or soldering activities performed under § 75.1106. MSHA's policy on § 75.1106 clearly states that methane tests conducted under this section must be made in locations where methane is likely to exist, and in no case is cutting, welding or soldering permitted in an atmosphere that contains 1.0 percent or more of methane. Since the face, roof, ribs, floors and any fully or partially enclosed areas of an underground coal mine are locations where methane is likely to exist, methane tests must also be made at or near the surface of these areas (not 12 inches away) and within any fully or partially enclosed areas that may be exposed to the aforementioned ignition sources. Welding, cutting or soldering activities are prohibited if any methane levels are 1.0 percent or greater within the affected areas. MSHA recommends the use of probes for methane detectors to take some of these measurements.
In a longwall mining system, adequate testing, cleaning, and rock dusting will generally require raising the chain conveyor and securing it above the mine floor before cutting, welding, or soldering operations begin. In this way, the space beneath the conveyor line can be ventilated and tested for methane, accumulated combustibles can be removed, and the area can be thoroughly rock dusted. Where raising the conveyor line is not practicable, other measures may be necessary to minimize the danger of ignitions.
During and after the cutting, welding, or soldering, this section also specifies that a diligent search be made for fire. This is a particularly important precaution because longwall chain conveyor line components or covers on other types of equipment may obscure a small fire.
75.1106-2 Transportation of Liquefied and Nonliquefied
Compressed Gas Cylinders; Requirements
This Section does not prohibit the transportation on mantrips of Dewars used with supplied-air breathing devices or oxygen bottles for self-contained breathing apparatuses or for first-aid treatment. In addition, the transportation of any compressed oxygen cylinders associated with approved self-contained self- rescuers are not controlled by this standard because they are personal protective devices rather than mining equipment.
75.1106-3 Storage of Liquefied and Nonliquefied
Compressed Gas Cylinders; Requirements
Paragraph (b) of this Section does not require that the cylinders be constantly attended while repair work is in progress and cutting or welding is done intermittently. However, the cylinders must be removed from the area inby the last open crosscut when the repair work is completed or when the repair work is interrupted for periods of time in excess of 15 minutes.
The term "when not in use" as used in paragraph (c) is not intended to be applied to intervals between intermittent cuts or welds at a given location while work is in progress and the cylinders are attended.
75.1107-1 Fire-Resistant Hydraulic Fluids and Fire-Suppression Devices
on Underground Equipment
"Unattended enclosed motors, controls, etc.," as used in paragraph (a)(3) means a reasonable enclosure to afford protection against personal contact with energized parts and against internal deposition of dust. It does not mean "explosion proof." The electrical insulation of components within the "unattended enclosed" equipment is not considered combustible material. A determination should be made in respect to this section because equipment mounted on combustible material, such as untreated wood, coal, or coal dust, would be considered combustible. Equipment mounted on a metal carriage (skid) on the bottom or a top shield, as applicable, will be acceptable as "equivalent" as used in paragraph (a)(3)(iii) provided: a 4-inch air space exists between the unit and the carriage or top shield; the carriage or top shield is substantially constructed of metal at least 1/8-inch thick; and the carriage or top shield covers the entire underside or top surface of the unit, as applicable, and extends at least 2 feet beyond the unit on all four sides."Unattended enclosed" equipment referred to in paragraph (a)(3) mounted on fire clay or a similar noncombustible mine floor will be acceptable as "equivalent," provided the floor is free of coal, coal dust, or other combustibles.
Small rubber-tired wheels (rim diameter 6 to 8 inches) on mobile transformers do not constitute combustible material within the meaning of paragraph (a)(3)(iii) and need not be removed from unattended electrical power equipment. This interpretation should not be construed to permit the presence or use of other combustible materials at the device, such as a wooden platform base, and shall be restricted to situations and equipment involving only small rubber-tired wheels.
In some instances a determination must be made in regard to similar noncombustible electrically-powered equipment. Careful consideration should be given to the equipment as to its similarity to enclosed motors, controls, transformers, and rectifiers in regard to its being located in a fireproof area or structure.
"Flammable fluid," as used in this section, means any liquid having a flash point below 140°F. This does not include lubricating oil and grease. Electrical cables are required to conform to Schedule 2G only if the equipment is installed in accordance with paragraph (a)(3)(iii) which requires the cables to meet Schedule 2G or that the cables be enclosed in metal conduit.
The intent of this section is that timber supports or other timber appurtenances should be considered as combustible material. Enforcement of this regulation may cause difficulty for some installations. Removal of or substitution of metal supports for the timber may not always be practical. Alternative equivalent fire protection in these instances could be provided by using asbestos boards or metal plates, considering the merits of each existing installation individually.
The "controls" in paragraph (a)(3) are intended to mean large power controls on a working section or other power distribution center. It is difficult to identify all such controls by an ampere rating, and some judgment must be used by the inspector. Questions may arise as to whether an "on-off" switch for an enclosed motor should be included as a "control" and whether such control could be mounted on a wooden post.
Such practice can be tolerated if the switch is fully enclosed in a metal box comparable with paragraph (a)(3)(iii), which requires cables to meet Schedule 2G or be enclosed in metal conduit.
Brake fluid used in manually-operated automotive-type braking systems is not considered to be hydraulic fluid within the meaning of paragraph (b) of this section.
It is important that equipment, to be considered attended, be in line of sight of a miner at least once during a 30-minute period. If the normal duties of a miner require that the miner face in one direction opposite to a machine, for example at a belt discharge point, it can be assumed that the miner will turn his head to the machine behind him often enough to comply with the 30-minute requirement of paragraph (c). However, if a machine is closer to a miner than 500 feet but is around a corner, it would be classed unattended unless the normal duties of the miner require him to pass by the obstructing corner during every 30-minute interval, and he or she has reason to look around the corner when passing.
Paragraph (d) of this Section requires that machines normally used at the face be inspected (for fire), and the input powerline deenergized when the miner leaves the area for more than 30 minutes. Deenergization means disconnecting the power cable, or equivalent, at the power center.
75.1107-3 Fire-Suppression Devices; Approved Components;
The purpose of this Section is to ensure that the components of the fire-suppression device are of the type approved by Underwriters' Laboratories, Inc., or Factory Mutual Research Corporation ("UL" or the initials "FM" in a diamond-shaped box will be on the components or device). Generally, Underwriters' Laboratory, Inc., approves the entire system, whereas Factory Mutual Research Corporation approves components. Some hardware components on a fire-suppression device, such as nuts, bolts, clamps, brackets, and the like, need not bear UL or FM approval, but sound engineering judgment should be exercised in overall approval of such a device. Components of a type not listed as approved, or not installed in accordance with the recommendations of a nationally recognized testing laboratory (UL or FM), may be accepted if such components are of a type and installed in a manner approved by the Secretary, as determined by the district manager. However, components of fire-suppression devices on attended and unattended equipment shall be listed or approved by UL or FM where these companies have listed or approved the type of components used in a system.
The Approval and Certification Center has conducted tests on American Biltrite Rubber Company's Cover Compound No. 22107, accepted it for listing, and authorized the marking "USBM-2G- 13C."
Hoses manufactured during 1970, 1971, and 1972 with Biltrite Compound 22107 will be recognized and accepted as complying with paragraph (c) of this Section even though they are not marked 2G- 13C.
The examples of the code letter identifications of Stratoflex 212 and 215 hoses are:
Stratoflex 212-8 H-4-V
Stratoflex 215-8 H-4-V
The numbers "212" and "215" identify the type hose, "-8" is the specific size (other members may appear in this location), "H-" indicates the hose was manufactured at Hohenwald, Tennessee, and "V" indicates the year of manufacture as 1970. "W" and "X" indicate 1971 and 1972, respectively.
"Where appropriate," as used in paragraph (d) of this Section, calls attention to the fact that most manufacturers' specifications refer to surface installations and, on occasion, these specifications may not be appropriate for underground installations. This determination will have to be made on a mine-by-mine basis by the district manager.
75.1107-4 Automatic Fire Sensors and Manual Actuators;
Installation; Minimum Requirements
The "50 square feet of top surface area," referred to in this Section means the 50 square feet of top surface area and does not include the side surfaces of the machine or its components.
Heat detecting Protector Wire is acceptable as a sensor in minimum lengths of 12 inches, provided the wire is properly secured by soldering or other substantial means.
To be effective, all heat detecting sensors, including sprinklers, must be kept free of oil, grease, rock dust, and other materials that may have an insulating effect.
Paragraph (a)(2) of this Section requires that at least two manual actuators should be installed on all continuous-mining machines and machines with dual controls purchased prior to the effective date of this Section. Some of the smaller pieces of equipment may be equipped with one actuator.
Paragraph (a)(2)(i) of this Section requires that manual actuators on remote-controlled equipment shall be within easy reach of the operator's normal operating position and should be both insulated and clearly identified.
Remotely controlled continuous mining machines can be advanced beyond permanently supported roof while the operator remains in a location under permanent supports. When continuous mining machines are advanced inby permanently supported roof, fire suppression systems cannot be safely actuated as required by 30 CFR 75.1107-4(a)(2)(ii) unless special precautions are taken. Currently, there are two acceptable methods for actuating the fire suppression system on remotely controlled mining equipment:
- the system can be manually actuated if, at all times, the actuator is located where the roof is permanently supported; or
- the system can be actuated remotely from a permanently supported location, and the actuation device can be operated by its own power source, independent of the electrical power provided by the trailing cable, as required by 30 CFR 75.1107-4(c).
A point-type sensor is a bi-metal strip contact or, thermocouple,or similar device. If other sensors (plastic-covered wire,radiation, gas, smoke) are used, equivalent protection shall be provided. Manual application at a sprinkler system should consist of a water hose nozzle arrangement or equivalent in the immediate vicinity. This type back-up system is also desirable for other suppression devices.
Two or more manual controls shall be installed where practical."Where practical" has reference to the size of the machine protected and possible avenues of approach. One control, for example, may suffice on a small roof drilling machine. Normally,the two controls should be on opposite ends or at least one of them in a position away from the operator's cab. The purpose of the two controls is to offer an alternate, should fire, heat or smoke engulf one set of controls.
Sensors as addressed in paragraph (b) shall, where practicable,be installed above the area of the equipment that is likely to produce the most heat in the event of a fire.
Paragraph (c) requires that where the fire-suppression system is dependent on the mine power supply, the power supply to the fire-suppression system must originate on the line side of the overload protection of the equipment being protected.
The purpose of paragraph (e) of this Section is to provide a rapid means of determining that the system is operative. Any effective method will be acceptable.