Questions and Answers on Rescue and Recovery Operations Following Coal Mine Fires and Explosions

Prepared by The National Mine Rescue Association

(Printed 1928--revised 1938), (Reprinted 1943), (Reprinted 1948), (Reprinted 1949), (Revised 1951), (Revised 1964), (Revised 1977), (Revised 1999)

Committee on Revision (1999)

Gerald E. Davis, MSHA, New Stanton, PA
Ronald Costlow, MSHA, Johnstown, PA
Lincoln Selfe, MSHA, Morgantown, WV
Dennis Vicinelly

Past Committee Members Responsible for the Preparation of These Questions and Answers

FOREWARD

These questions and answers were prepared originally in 1928 by a committee of the National Mine Rescue Association.

The object was to standardize the procedure in connection with the recovery operations following mine fires and explosions, and at the same time set up that which would be instructive in training new men for this emergency work.

After gaining experience, this publication has been periodically revised and brought up-to-date by a committee appointed for this purpose, assisted by the general membership of the Association.

This revision is dedicated to the miners who have lost their lives during firefighting and rescue and recovery operations in the coal mines of the United States. It is the wish of the committee that this revision will help to prevent any more loss of life in this way.

MINE GASES

1. Name the common gases found in coal mines following a mine fire or explosion?

Carbon monoxide, carbon dioxide, and methane, oxygen, nitrogen, hydrogen, and other hydrocarbons.

2. What is a dangerous mine atmosphere?

A dangerous mine atmosphere is one that is or is likely to become poisonous to breathe, deficient in oxygen, or explosive.

3. What is the principle combustible gas found in coal mines?

Methane (CH4) is the principle combustible gas found in coal mines.

4. What is the explosive range of methane-air mixtures?

5 to 15 percent of methane in air is explosive.

5. To what extent must the oxygen content be reduced before an explosion of methane and air is impossible?

For a mixture of strictly methane and air, the oxygen content must e 12 percent or less. It is however, significant to note that there is a combination of combustible gases following explosions and during fires, so the maximum allowable oxygen will vary according to variations in the combustible and inert gases.

6. What is the explosive range of carbon monoxide-air mixtures?

12.5 to 74 percent carbon monoxide in air.

7. What is the explosive range of hydrogen-air mixtures?

4 to 74 percent carbon hydrogen in air.

8. To what extent must the oxygen content be reduced before an explosion of hydrogen is impossible?

5 percent or less.

9. Name the inert gases found in coal mines?

Carbon dioxide (CO2) and nitrogen (N2).

10. State where you would generally find methane, carbon monoxide, and hydrogen sulfide?

Methane may be found anywhere, but is most likely to be encountered in virgin coal, roof cavities, high places, abandoned workings, and places that are improperly ventilated. Carbon monoxide may be found in small quantities after blasting and will be found after an explosion or in the return from a mine fire and use of diesel equipment underground. Hydrogen sulfide may be found in old pipelines, stagnant water, fire areas and occasionally in active workings, usually associated with broken bottom.

11. What gas or gases support combustion?

Only oxygen.

12. How are persons affected by breathing the various gases found in coal mines?

1. A deficiency of oxygen in the air being breathed deprives the body of the oxygen required for normal life support. Noticeable symptoms such as faster and deeper breathing, dizziness, rapid heart beat, and headache occur when the air contains as little as 15 percent oxygen unconsciousness may occur when the air contains 9 percent oxygen and life is greatly endangered when the air contains 7 percent oxygen. A flame safety lamp will no longer burn when the oxygen content is below 16.25 percent.

2. Carbon monoxide breathed in air reduces the capacity of the blood to carry sufficient oxygen, which deprives the brain and body tissues of the oxygen they require for normal functioning. The generally accepted maximum allowable concentration for an 8-hour exposure with normal oxygen is .005 percent. Somewhat higher concentrations may be considered allowable for short periods of exposure. For example, .04 percent can be inhaled for one hour without appreciable effect but .15 percent is dangerous to life after exposure of one hour, and .4 percent will cause death in less than an hour.

3. Hydrogen sulfide in very small amounts will cause irritation of the eyes and respiratory passages, including the lungs, concentrations as low as .07 percent will cause rapid unconsciousness, cessation of respiration, and death.

FIGHTING AND SEALING COAL MINE FIRES

13. What are the major causes of fires in coal mines?

Electricity, open flame, ignition of gas, explosives, cutting and welding, smoking and smokers= articles, spontaneous ignitions, friction, and surface fires communicated to underground workings.

14. What are the usual methods of controlling or extinguishing mine fires?

1. Direct attack with water, chemicals, rock dust, or sand. 2. Foam. 3. Enclosing fire area with tight seals. 4. Flooding affected area 5. Flushing enclosed area with silt or other material. 6. Enclosing fire area with inert barriers. 7. Inundating with inert gases.

15. When should you decide to seal a fire area or mine?

When it is no longer reasonably safe or feasible to fight the fire directly because of a build up of combustible gases, bad roof due to heat, insufficient firefighting materials, too large an area engulfed by fire, etc..

16. What is the objective of sealing?

The object is to control and extinguish the fire by cutting off the oxygen supply so as to reduce the oxygen below that which will support a flame or combustion; also, to minimize or eliminate the possibility of an explosion.

17. What are the principle hazards in sealing a mine fire?

When coal burns, explosive and asphyxiating gases are liberated or produced and the heat from fires causes roof falls. Therefore, the installation of seals, the roof falling, or other firefighting activity may cause an explosive mixture of gases to reach the fire causing an explosion. In addition, there is a potential for workmen to be overcome by asphyxiating gases because of the need to work in the return airways and because of roof falls changing the pattern of ventilation. It is important that the air returning from the fire area be monitored for explosibility.

18. Should the intake or return be sealed first, or both together?

No fixed rule should be established for sealing, but the procedure must be governed by the conditions surrounding each fire. It is, however, preferable to erect both intake and return seals simultaneously. It may even be advisable to devise a method of having doors in the seals closed after all workmen have returned to the surface. 19.Q. What distance should seals be from a fire?

Conditions govern this. As the objective in sealing is to cut off the air so that oxygen will be consumed to the point that there is not enough oxygen to support combustion, the smaller the area sealed, the quicker this will be accomplished. Roof conditions, amount of combustible gases being given off, the intensity of the fire, and the number of seals required are the principle factors to be considered when selecting seal locations.

20. Should temporary seals be erected first?

Not necessarily. Circumstances surrounding each fire will determine whether or not temporary seals should be erected. Factors to be considered when making this determination are the availability of permanent sealing material, the rate of rise of combustible gases, the rapidity of the spread of the fire, the accessibility of the seal locations, etc..

21. What materials should be used for temporary seals?

The most common and practical materials are those normally used within the mine such as brattice material, brattice boards, and other sealing materials. Whatever the materials used, the edges should be sealed with urethane foam or other material to make them as air tight as possible.

22. Should work continue in the mine after seals are completed?

Emphatically, no! The main hazard after sealing a mine fire is the possibility of an explosion within the sealed area. All men should be removed as quickly as possible after completion of work on the seals. Normally, no one should enter the mine when it is known that there is an explosive atmosphere within the sealed area. Samples to determine whether or not the atmosphere is explosive should be collected through boreholes from the surface whenever possible. Analysis of collected samples will determine when it is safe to re-enter the mine and continue work. Otherwise, the first tip into the mine after sealing should be for the purpose of collecting samples from the sealed area. The number of people making this trip should be limited to as few as necessary and how soon the trip should be make after seals are completed will depend to a large extent upon the size of the sealed area, the amount of combustible gases in the area when the seals were constructed, and the normal methane liberation in the area.

23. What are the main factors to be considered in erecting permanent seals?

All permanent seals shall be designed to comply with Title 30 Code of Federal Regulations.

UNSEALING FIRE EXPLOSION AREAS IN COAL MINES

24. What does the presence of carbon monoxide in sealed areas indicate?

The presence of carbon monoxide is an indication of an active or recently active fire.

25. How much oxygen is considered reasonably safety before attempting to unseal a fire?

The amount of oxygen under these circumstances is critical because of the possibility of explosion when unsealing a fire area. Ideally, the oxygen content should be such that the atmosphere in the sealed area is not explosive and cannot become explosive when air is added. Where this is not possible, the procedure for recovery should insure that men are not in the mine when an explosive mixture exists in the sealed area unless the area has been examined and there is no fire. 26.Q. What are the principle factors that govern the amount of time a fire area must be sealed before being reopened?

Some principle factors are: Tightness of seals and enclosed area, influence of barometric pressure on enclosed area; character of burning material and overlying strata; extent and intensity of fire; location of seals with respect to mine ventilation; the extent of the area under seal; composition of gases in the sealed area.

27. How would you determine when it is safe to reopen a sealed fire area?

Trends of several gases provide a better indication of whether or not a fire is Aout@. The levels of carbon monoxide may never reach zero even though it may be safe to re-enter the mine. Stability of the sealed atmosphere provides a good indication of the status of the fire.

28. What effect, if any, does the presence of carbon dioxide that is produced in the sealed area have on the fire?

The amount of carbon dioxide present under these circumstances would have very little effect on the fire, but is a factor to be considered in determining whether or not the atmosphere is or may become explosive. Carbon dioxide may be introduced into a sealed area to help control the fire and help create an inert atmosphere.

29. What are some of the preparations that should be made before unsealing a fire area?

A complete and detailed plan should be prepared and agreed to by various interested parties. Necessary adjustments should be made in the ventilation to assure that an ample quantity of air will be available and that the air that passes by or through the sealed area is conducted in such a manner that it will not pass over power wires or any other potential ignition source and shall be directed by the shortest means to the surface. The area adjacent to the seals should be heavily rock dusted.

30. Briefly describe two methods that have been successfully employed for the recovery of a fire/explosion area.

There are, in general, two systems that may be employed: 1. Recovering the fire area in successive blocks by means of air locks. 2. Reventilation of the fire area after there is conclusive evidence that the fire has been extinguished, or that the atmosphere is not explosive and will not become explosive with the addition of air.

31. Describe the method of recovering a sealed fire/explosion area by the use of air locks.

The purpose of air locking is to recover portions of the sealed fire/explosion area or the entire area in a manner that will prevent increasing the oxygen content in unexplored areas to avoid an explosive atmosphere or rekindling or intensifying the fire.

When a suitable air lock has been erected, an oxygen breathing apparatus crew, fully equipped for the work at hand and supported by a fully equipped reserve crew, should enter the air lock through a man door and remove the seal.

After the seal has been removed, an oxygen breathing apparatus crew, with another crew in reserve, should advance and explore to the point where the next air lock is to be erected. General conditions should be observed by the exploring crew, temperature readings taken, an air sample collected to check previous analysis.

When a decision has been made to recover a sealed area by direct ventilation , an air lock should preferably be constructed near the intake seal. A rescue crew fully equipped for the work at hand breaks the seal, enters, observes conditions, takes temperature readings and air samples, returns to the fresh -air base. If the observations and examinations of the affected region have shown that condition are favorable, the return seal should be broken by an apparatus crew, then the air lock opened to admit air. While the area is being ventilated, the combustible gases in the main return should, if feasible, be kept below explosive limit. If this method of recovering a fire area is employed, it is advisable that all the men be out of the mine before the air is actual directed into the sealed area, unless it has been determined that the atmosphere in the sealed area is not explosive and cannot become explosive by adding air Some automatic arrangements should be employed which would give sufficient time for all persons to reach the surface before the fire gases were actually moved. A reasonable period should be given for the fire gases to be removed and frequently determinations should be made of the return from the mine, and the time for any person to enter should be governed by the quality of the air. If the workings under seal are of an extensive nature it will probably be advisable for crews equipped with oxygen breathing apparatus to reenter the mine and clear out pockets of standing fire gases that may be present.

Mine Explosions

33. What are the principal causes of mine explosions? 

Ignition of methane or coal dust or both by electric arc open flame (including mine fires), misuse of explosives friction, lightning strikes, smoking articles, etc.

34. How can mine explosions be prevented or their effects minimized?

By adequate ventilation, rock dusting, mine dust control permissible electrical equipment and proper use of permissible explosives.

Procedures and Duties At Fires and Explosions

35. In case of a mine fire or explosion, who should notified?

Notify as soon as possible, higher company officials state mining agency, federal mining agency, and representatives of the mine workers. Each of these groups/agencies should have an up-to- date Mine Emergency Response plan that addresses assigned areas of responsibility in the event of a mine emergency. Also, any adjoining mines that are connected to the affected mine should be notified.

36. What are some factors that must be considered early to assure a well organized operation?

Periodically conduct mine emergency drills and frequent training on the mine emergency response plan.

37. What one factor is most critical to insure the safety of survivors in the mine? 

The mine ventilation. The fan or fans should be examined and repaired as necessary, then attended or other action taken to assure continued operation. Ventilation should not be prematurely changed.

38. A major factor to be concerned with during recovery following an explosion is the possibility of another explosion. List the methane ignition sources which are the most likely to be encountered in the affected areas that have not been explored and ventilated?

1. Fire that was started by the explosion. 

2. Electrical arc that may be created by the short-circuited batteries or power wires that have not been de-energized.

39. In addition to assuring that the fan or fans are operating, what is another important step to be taken in the attempt to save survivors?

Endeavor to communicate with survivors and direct them to the best means of escape from the mine.

40. What are the main objectives of the rescue and recovery work after a mine explosion?

1. Safety of the persons involved in Rescue/Recovery.

2. Rescue live persons and recovery bodies. 

3. Recover the mine.

41. While fighting a mine fire, what type of major accident should the firefighter be most concerned with? 

An explosion is the major accident that is likely to occur during firefighting operation.

42. How should mine firefighters protect against the occurrence of an Explosion?

The air returning from the fire should be monitored for explosibility, and ventilation should be controlled closely and maintained over the fire constantly.

43. Should one man be in charge of the rescue or recovery work?

Yes, generally a representative of the company.

44. Should there be a advisory committee to the man in Charge? 

Yes. The committee should be composed of representatives of the State mining agency, Federal mining agency, the miners, and others.

45. Should there be a plan made for specific phases of firefighting rescue and recovery procedures such as sealing or unsealing mine fires or recovery of miners following an explosion?

Yes. The man in charge and the advisory committee should devise a plan of operation which should be followed closely.

46. What are some factors that may be critical to the safe firefighting or explosion recovery activities, and which would not normally be known or readily available to planners?

Location of all energized power wires or equipment; location of all battery equipment or equipment on which batteries are installed; location of diesel equipment; location of pressurized containers, such as acetylene or oxygen cylinders; and the location and description of any other equipment or supplies that may influence the planner.

47. How should the work be divided?

Work shifts should be determined by the persons in charge and should be determined by the need of the recovery operation.

48. Should there be a man in charge of the underground work on each shift?

Yes, generally a company representative with experience in such work.

49. Should there be a advisory committee to the man in charge on each shift underground?

Yes. A committee should be composed of representatives of State mining agency. Federal mining agency, and others as appropriate.

50. Should there be any restrictions on the number of people permitted underground?

Yes. Only those people necessary to insure the suitable progress and safety of the operation which would include supply men, backup workers, supervisors, etc.\

51. After entering a mine following an explosion, what examination should be made?

Examine return airways for smoke or other indications of active fire.

52. Following an explosion, how is the location of the first fresh-air base determined?

Exploration is continued in intake air to the point where normal ventilation controls have been destroyed and ventilation is short circuited. At this point, the first fresh- air base should be established.

53. Describe a fresh- air base?

The place to which fresh air has been conducted, and at which stoppings (seals) or other ventilation controls including an air lock have been installed in a manner that will prevent reventilation of any area that has not been explored and examined.

54. When should the fresh-air base be advanced?

Only when an area inby the present fresh-air base has been examined and the stoppings installed to permit the explored area to be reventilated without disturbing the inby area that has not been explored. 

55. Should exploration trips be made ahead of the fresh- air base or in other areas where an irrespirable atmosphere is or nay be present? 

Yes. Crews wearing self-contained breathing apparatus should make such trips for gathering information, reestablishing ventilation, rescuing workmen, searching for bodies, etc.

56. What should be the distance of trips ahead of fresh air?

The object of the exploration, the type of communication used; conditions (such as height) of travel way, etc, will govern the distance to be traveled; always keeping in mind the time limitations of the apparatus.

57. Under what conditions is it not advisable for breathing apparatus crews to make trips ahead of fresh air?

1. Such exploration trips should not be taken under the following conditions: 

2. In dense smoke, except with life line attached to each member and then only for very short trips to save life, turn valves, or to open or close doors essential to the operation.

3. When an explosion is probable.

4. In dangerously high temperature with high humidity.

5. When apparatus not adequately charged or in unsafe condition.

6. When the reserve crew has less members than the advance crew.

58. What kind of material should be used to build temporary stoppings?

Workmen wearing breathing apparatus should install temporary stoppings with brattice material, pogo sticks, inflatable stoppings, etc. Such stoppings should be replaced as soon as possible with more substantial such as cement block, wood-framed brattice sealed with rigid foam, or other more permanent type structure.

59. What should be done by breathing apparatus crew when fires are found during exploration?

Every effort should be made to reach and extinguish all fires discovered. If this is not possible, the crew should return to the fresh air-base.

60. Should there be a telephone or other means of communication between the fresh-air base and the outside?

Yes, so that men and material can be provided without delay and that instruction and information can be relayed promptly between the person in charge underground and the person in charge on the surface.

61. Should the man in charge of each shift have a map of the mine?

Yes, so that he can follow progress, make plans, give relay information accurately.

62. Should information be relayed to relatives of possible victims and to the news media?

Yes. Normally one spokesman should be selected to relay factual information about the operation

63. What should the engineering department be responsible for during firefighting or recovery operations after an explosion? 

1. Provide up-to-date maps of the mine showing normal ventilation and ventilation controls (stoppings, overcasts, etc.) 

2. Keep map current by recording progress, changes in ventilation, and other pertinent information such as location of bodies, equipment, etc.

64. Following a mine explosion what early action should the electrical department take?

1. Disconnect and lock out all electric power entering the mine or affected portions when authorized to do so, and lock out all other de-energized circuits.

2. Notify the electric company that under no circumstances should the electric power be "cut off" without notifying the mine.

3. If is a shaft or slope mine, examine and service necessary hoists and elevators.

65. What are some of the duties of the safety department during the early stages of firefighting or explosion recovery operation?

Make arrangements for rescue teams including facilities and maintenance of equipment, food and lodging. Arrange for medical or first-aid treatment for injured persons or handling of bodies if necessary.

66. What main types of workers should be on each shift? 

Crews with breathing apparatus, crews to build stoppings and crews to transport and handle supplies.

67. What attributes should a person have before being selected as a mine rescue team member? 

The person selected should be cool, competent person who has demonstrated in his past work a willingness to be a good "team" member. The person should also possess extensive knowledge of mining and should be mentally sound and physically fit.

68. What training should a mine rescue team member have before being qualified to participate in mine rescue work?

They should be trained and retrained in accordance with Federal or State requirements for qualification.

69. How many people constitute constitute a rescue team?

At least five and preferably six men should compose a rescue team with the same number fully equipped at the fresh-air base. A crew of less than five may make short explorations for special purposes when a similar number of apparatus men are in reserve at the fresh-air base.

70. What equipment should rescue parties have with them?

In addition to the standard equipment such as electric cap lamps and self-rescuers, they should be equipped with approved self-contained breathing apparatus that have been properly tested and inspected under the supervision of a competent person. They should have all the pertinent background information, a copy of the latest map of the mine workings, and at least an approved and tested methane detector, carbon monoxide detector, oxygen detector and thermometer.

71. What should the captain of an apparatus crew confirm before leaving the fresh-air base?

Make sure that all apparatus are operating properly and check to see that all material necessary for the exploration is on hand and working. The captain should consult with the man in charge relative to the purpose of the trip and extent of travel; also be sure that a back-up rescue team with all necessary equipment is in readiness at the fresh-air base.

72. How should the exploration ahead of the fresh-air base be conducted?

Exploration ahead of the fresh-air base should be determined by the advisory committee after evaluation of conditions encountered by the rescue teams.

73. What communications should be maintained with rescue team and fresh-air base?

They must be in contact with the fresh-air base at all times using sound system.

74. What action should be taken if a communication failure occurs between teams and the fresh-air base?

Teams should retreat to the fresh-air base.

75. Should apparatus crews recover bodies from unventilated areas?

Ordinarily, men encumbered with apparatus should not exhaust their strength in carrying bodies any great distance to fresh air.