Section 8

Mine Rescue Statement of Facts

  1. Draeger BG-174 A

  2. Mine Gases

  3. Mine Rescue & Recovery

  4. Firefighting & Explosions

  5. Ventilation

I. Draeger BG-174 A
  1. The positive pressure leak test is to insure that no oxygen escapes to the outside atmosphere during operation of the apparatus.
  2. A leaking diaphragm will create a low opening pressure.
  3. An old diaphragm which has lost its flexibility due to age will create a high opening pressure.
  4. The pressure relief valve is designed to open when the pressure within the breathing circuit is between +10 and +40 millimeters (+1 mbar and +4 mbar) of pressure measured on the water gauge.
  5. Once zero adjustment has been made on RZ-25 tester, do not readjust setting for balance of tests.
  6. All connections must be tightened on apparatus and zero adjustment made on RZ-25 tester prior to connecting breathing hoses to apparatus.
  7. The exhalation valve should allow the breathing air to pass in only one direction toward the regenerative canister.
  8. During the exhalation valve test, if valve is operating properly, breathing bag should not deflate.
  9. The inhalation valve should only allow the breathing air to pass in one direction toward the face mask.
  10. During testing of the inhalation valve, if valve is operating properly, the breathing bag should not inflate.
  11. During the positive pressure leak test, the needle on the RZ-25 tester should not drop more than 10 mm H2O or 1 mbar in 60 seconds.
  12. The screw ring cover on the lung demand valve assembly and connections on the breathing bag are hand tight connections.
  13. The negative pressure leak test is to insure that no toxic gases enter the breathing circuit during operation of the apparatus.
  14. During the negative pressure leak test, the needle of the RZ-25 tester should not rise more than 10 mm H2O or 1 mbar in 60 seconds.
  15. The BG-174A is equipped with a pre-flushing device which automatically purges the nitrogen rich ambient air, initially found in the breathing circuit, with pure oxygen.
  16. Once the oxygen cylinder valve is opened and the unit is charged with oxygen, the pressure gauge on the oxygen cylinder and the chest gage on the flexible line must equalize to within 10 percent of one another.
  17. All BG-174A oxygen cylinders that show zero pressure on the gage must be purged and vacuumed to remove any contaminant or moisture that may have entered due to lack of pressure in the cylinder.
  18. The lung demand valve automatically goes into action if more than the allotted dosage of 1.4 - 1.7 LPM of oxygen is consumed by the wearer.
  19. During the lung demand valve test, the valve should open between -10 mm H2O (-1 mbar) and -40 mm H2O (-4 mbar).
  20. The breathing bag volume test is done to insure that the breathing bag has correct volume, which should be at least five liters.
  21. Each complete stroke of the bellows on the RZ-25 tester is equal to 0.5 liter.
  22. During the bypass test, a failure of the bypass valve to instantly provide oxygen into and fill the breathing bag at a rate of approximately 50 LPM in less than 10 seconds is an indication of an internal failure in the oxygen distributor.
  23. Constant dosage in the BG-174A is preset at approximately 1.5 liters/minute.
  24. Three factors affecting constant dosage are: diameter of dosage orifice, constant pressure, and elevation and atmospheric pressure.
  25. The dosage orifice within the oxygen distributor has an opening of approximately 0.17mm.
  26. Oxygen under a constant pressure of 57 PSI is forced through the orifice at an approximate rate of 1.5 liters/minute.
  27. The constant pressure of 57 PSI is maintained by the reciprocating action in the oxygen distributor.
  28. During the constant dosage test, the breathing bag is deflated, the RZ-25 tester is set to red dosage, and the pressure relief valve cover is plugged.
  29. During the constant dosage test, the needle of the RZ-25 tester should automatically settle between 1.4 and 1.7 LPM.
  30. Although the RZ-25 tester measures dosage, it is not a flowmeter.
  31. The RZ-25 tester is operated by over pressurizing the breathing circuit.
  32. The pre-flush/dosage line connection is tightened by hand.
  33. The plug on the training canister is tightened by wrench.
  34. When it is assured that all hand tight and wrench tight connections are securely fastened, low dosage can usually be attributed to a damaged o-ring or washer.
  35. Any leak in the breathing circuit will prevent the apparatus from over pressurizing, thus indicating a low dosage.
  36. The oxygen cylinder connection is tightened by hand.
  37. The locking screw on the saliva trap is tightened by a wrench.
  38. The hose adapter on the RZ-25 tester is tightened by hand.
  39. The breathing hoses are tightened by hand.
  40. During the constant dosage test, a reading of less than 1.4 LPM is low dosage.
  41. A high dosage indication can almost always be attributed to a leak at the valve head inside the lung demand valve.
  42. An internal leak at the valve head inside the lung demand valve may not be detectable with the positive and negative pressure leak tests.
  43. The warning whistle is designed to activate when the pressure in the oxygen cylinder has dropped to approximately 20 percent of the original cylinder pressure.
  44. During the whistle activation test, the warning whistle should activate at approximately 700 PSI for a four hour apparatus.
  45. If during testing the warning whistle fails to activate at the prescribed setting, the warning whistle should be removed from the apparatus and returned to National Mine Service for adjustment.
  46. If while wearing the apparatus the warning whistle should sound with each inhalation or with each activation of the manual bypass valve, this is another indication of clogged sieves in the oxygen distributor rather than a defective whistle.
  47. During the whistle duration/manual cut-off test, the warning whistle should sound for 20 to 60 seconds before automatically sealing itself.
  48. If during the whistle duration/manual cut-off test, the warning whistle sounds less than 20 seconds, it may not be giving the user an adequate warning.
  49. If during the whistle duration/manual cut-off test, the warning whistle sounds longer than 60 seconds, it is wasting valuable oxygen.
  50. The manual cut-off lever is located on the oxygen distributor.
  51. The manual cut-off lever is designed to isolate the chest gage in the event the gage or the flexible line develops a leak during operation.
  52. The valve screw should be positioned so that the chest gage and flexible line are isolated when the manual cut-off lever arm is lifted to a 30 to 45 degree angle from the horizontal.
  53. Prior to testing whistle duration and the manual cut-off valve, turn oxygen cylinder valve off, lift the manual cut-off lever, open oxygen cylinder valve (with the RZ-25 tester set on negative pressure pumping), and start the stopwatch.
  54. When the system is pressurized, the high pressure and medium pressure lines can be tested for leaks by coating the connections with a soap lather or leak detection solution.
  55. The BG-174A should be stored to protect against: dust, sunlight, heat, extreme cold, excessive moisture, damaging chemicals, and mechanical damage.
  56. All parts exposed to the circulatory system of the BG-174A must be thoroughly washed in a good detergent/disinfectant, thoroughly rinsed, and dried after each wearing.
  57. The face mask, breathing hose assembly, breathing bag, and lung demand valve assembly are parts exposed to the circulatory system that must be thoroughly washed after each wearing.
  58. Before washing the lung demand valve assembly, it is absolutely necessary to isolate the lung demand valve.
  59. An improper disinfectant or one that is not diluted properly could cause the rubber or neoprene parts to deteriorate prematurely.
  60. Alcohol is not to be used to clean or disinfect any parts of the BG-174A .
  61. If alcohol is used to disinfect or clean, it will break down the rubber in the face mask, hoses, and breathing bag.
  62. The temperature of the air used to dry parts should not go above 140 degrees F (60 degrees C).
  63. Storing the rubber or neoprene parts in areas with fluorescent lighting will have the same effect as direct sunlight.
  64. Replace the o-ring at the oxygen cylinder connection at least once every six months.
  65. All rubber or neoprene sealing rings should be replaced at least once every two years.
  66. A new inhalation valve should be inserted into the lung demand valve assembly at once every two years.
  67. The lung demand diaphragm should be replaced after at least three years usage.
  68. The o-ring under the speaking diaphragm should be replaced at least once every three years.
  69. The o-ring under the speaking diaphragm should be replaced at least once every three years.
  70. The oxygen cylinder must be retested by a certified testing facility every five years.
  71. The test date in month and year is stamped on top of all oxygen cylinders.
  72. The lung demand valve assembly should be replaced at least every six years.
  73. The warning whistle should be returned to National Mine Service for overhaul after at least six years usage.
  74. When copper gaskets are removed from the BG-174A for any reason, they should not be reused.
  75. Only USP medical oxygen is to be used to fill the BG-174A oxygen cylinders.
  76. Before filling any oxygen cylinder, check the service rating and hydrostatic test date stamped on the cylinder.
  77. If the oxygen cylinder is rated at 2600 PSI or 2850 PSI, it can be filled up to these pressures only.
  78. Only oxygen cylinders rated at 2850+ can be filled to 3135 PSI.
  79. The temperature in the areas for filling and storage of oxygen cylinders should be maintained at approximately 70 degrees F.
  80. During the filling cycle, the temperature in the oxygen cylinder will rise in proportion to how fast the cylinder is filled.
  81. A prerequisite for the safe use of an oxygen breathing apparatus is a proper maintenance program.
  82. It is very important that an accurate record be kept of each test performed on the BG-174A with the RZ-25 tester.
  83. When using a factory packed regenerative canister, insure that the string or tape seal is in place and the expiration date has not been reached prior to removing the end caps and inserting the canister into the apparatus.
  84. The expiration date is stamped on the white label attached to each factory packed regenerative canister.
  85. The expiration date on each factory packed regenerative canister appears as a Roman numeral and year.
  86. The BG-174A apparatus will not offer protection against poisonous gases absorbed through your skin.
  87. The wearing harness consists of two adjustable shoulder straps with double slide buckles and a waist belt.
  88. On the top of the oxygen cylinder is a safety device known as the pressure burst cap.
  89. The pressure gages are marked in increments of 200 PSI and are luminous, so you can see them in the dark or in other conditions that limit visibility.
  90. The special chemicals inside the regenerative canister absorb the carbon dioxide from the air that is exhaled by the wearer.
  91. There are two types of canisters you can use with the Draeger BG-174A apparatus, refillable training canister and factory packed disposable canister.
  92. The refillable training canister is made of stainless steel and can be used over and over again as long as the absorbent chemicals are freshly packed for each use.
  93. Inside the refillable training canister is a set of baffles designed to expose more surface area of the chemicals to the exhaled air.
  94. If the factory packed disposable rescue canister has expired, yet is still factory sealed, it can be used for training provided that the chemicals can be heard rattling around when the canister is shaken and the canister has not gained 10 or more grams in weight.
  95. The lung demand valve assembly contains the diaphragm, pressure relief valve, lung demand valve, and inhalation and exhalation valves.
  96. The pressure relief valve is the part of the lung demand valve assembly that keeps oxygen from building up in the breathing bag if you use less than the unit provides.
  97. The saliva trap is on the inhalation hose because it must be located on the lowest part of the apparatus when it is worn so that the moisture will settle there.
  98. Heat buildup within the unit’s system is produced when your exhaled air flows through the regenerative canister.
  99. The area where oxygen cylinders are filled and stored must have adequate ventilation to prevent a buildup of oxygen and reduce the potential for fire.
  100. If you’re using a high pressure oxygen pump to fill an oxygen cylinder, the pump itself should have a filter dryer installed on the gas inlet side of the pump to prevent moisture and dust from getting into the oxygen cylinder.

II. Mine Gases
  1. Hydrogen can be liberated when water or steam comes in contact with hot carbon materials.
  2. Hydrogen is produced by the incomplete combustion of carbon materials during fires and explosions.
  3. Toxic gases are produced by burning rubber, neoprene, or polyvinyl chloride (PVC).
  4. Oxygen is a supporter of combustion.
  5. Carbon monoxide is a product of incomplete combustion of any carbon material.
  6. Specific gravity is the weight of a gas compared to an equal volume of normal air under the same temperature and pressure.
  7. Normal air has a specific gravity of one.
  8. Carbon dioxide is colorless, odorless, and has a acidic taste over 10%.
  9. Methane is lighter than air.
  10. Carbon monoxide is explosive.
  11. Hydrogen sulfide is highly toxic.
  12. Nitrogen dioxide has a reddish-brown color in high concentration.
  13. Sulfur dioxide is nonexplosive.
  14. Nitrogen is nonexplosive.
  15. Oxygen has no odor, color or taste.
  16. The explosive range of methane in air is 5 to 15 volume percent.
  17. Carbon monoxide has no color, odor, or taste.
  18. Hydrogen sulfide has an odor similar to rotten eggs.
  19. Nitrogen dioxide is nonexplosive.
  20. The lower explosive limit of hydrogen is 4.0 percent.
  21. Nitrogen has no odor, color, or taste.
  22. Carbon dioxide is nonexplosive.
  23. Acetylene is formed when methane is burned or heated in air having a low oxygen content.
  24. Sulfur dioxide is highly toxic.
  25. Nitrogen is an asphyxiant in above normal concentrations.
  26. Continual exposure to hydrogen sulfide may dull the sense of smell.
  27. The affinity of carbon monoxide for hemoglobin is 200 to 300 times that of oxygen.
  28. The specific gravity of methane is 0.5545.
  29. The specific gravity of carbon dioxide is 1.5291.
  30. The specific gravity of carbon monoxide is 0.9672.
  31. Carbon dioxide is the product of oxidation including the decay of timbers.
  32. About 21 percent of normal air is oxygen.
  33. Blackdamp is a mixture of carbon dioxide, nitrogen and air which is oxygen deficient.
  34. Afterdamp is a mixture of carbon monoxide, carbon dioxide, methane, oxygen, nitrogen and hydrogen.
  35. Afterdamp is usually found after a mine fire or explosion.
  36. Hydrogen can be detected with a multi-gas detector or by chemical analysis.
  37. In some mines, carbon dioxide is liberated from the rock strata..
  38. To test for methane, use a methane detector or chemical analysis.
  39. Carbon monoxide can be detected by means of carbon monoxide detectors, multi-gas detectors, or by chemical analysis.
  40. Nitrogen dioxide is produced by burning and by the detonation of explosives.
  41. Smoke usually contains carbon monoxide and other toxic or asphyxiating gases produced by fires.
  42. Breathing air containing 10 percent carbon dioxide causes violent panting and can lead to death.
  43. The first symptom of carbon monoxide poisoning is a slight tightening across the forehead and possibly a headache.
  44. A mixture of coal dust in air reduces the explosive limit of methane.
  45. One and one-half to two percent methane together with coal dust in air may be explosive.
  46. Mines below the water table tend to have more methane than those above the water table.
  47. High temperature (or heat) cause gases to expand so they diffuse more quickly.
  48. The range of concentrations within which a gas will explode are known as its "explosive range".
  49. Any flammable gas can explode under certain conditions.
  50. It is much easier to remove a concentration of a light gas like methane by ventilation than it is to remove the same concentration of a heavier gas like carbon dioxide.
  51. Only detectors and chemical analyses can positively identify a gas.
  52. The effects of toxic gases depend on the concentration, toxicity, and exposure time.
  53. Asphyxiants are gases which cause suffocation choking.
  54. Firedamp is a mixture of methane in air that will burn or explode when ignited.
  55. If there is a sufficient amount of hydrocarbons in smoke, the smoke may be explosive.

III. Mine exploration & recovery

  1. One pull on the lifeline means that the rescue team wants to stop.
  2. Two pulls on the lifeline means that the rescue team is going to advance, move toward the captain.
  3. Three pulls on the lifeline means that the rescue team is going to retreat, move toward the No. 5 person (last person).
  4. Four pulls on the lifeline means that the rescue team is in distress or emergency.
  5. The first priority of rescue and recovery operations is team safety
  6. The second priority of rescue and recovery operations is the rescue of survivors.
  7. The third priority of rescue and recovery operations is the recovery of the mine.
  8. Whenever possible, it is best to enter the mine by way of the safest intake airway.
  9. When rescue teams travel in smoke, all team members should hold onto the lifeline or be linked together by means of a linkline.
  10. Before opening and traveling through any stopping inby which conditions are not definitely known, you should first erect a temporary stopping outby.
  11. The monitoring of the mine atmosphere for the presence of oxygen, methane, and carbon monoxide an important element of team exploration.
  12. Dinner buckets encountered during exploration are important because they may contain information about the whereabouts of survivors.
  13. Your captain must order the team to return immediately to the fresh-air base if a team member’s apparatus malfunctions.
  14. A debriefing is a session held when a team returns to the surface after completing an assignment to review what they saw and did.
  15. In potentially explosive atmospheres, nonsparking tools, nails, and spads should be used.
  16. When you have located a barricade, you should try to determine whether the miners inside are still alive and conscious.
  17. Mine rescue teams may find it necessary to use line brattice to sweep noxious or explosive gases from a face area.
  18. Explosions, fires, and other disasters frequently result in weakened roof and rib conditions.
  19. Before a rescue team goes underground, it will attend a briefing session.
  20. Information the team relays to the fresh air base as it proceeds is known as the "progress report".
  21. It is the responsibility of rescue team members to have all the information needed to do the work.
  22. When a team locates a body, its location and position should be marked on a mine map and on the roof or rib close to the body.
  23. The rescue team captain should regulate the team’s pace according to conditions encountered.
  24. When a body is first located, every effort should be made not to disturb any possible evidence in the area.
  25. In situations too hazardous for teams to explore and reventilate safely, teams may be instructed to seal the area.
  26. Before the team leaves the fresh-air base to travel inby, the captain should take note of the time of departure.
  27. It is recommended that team checks be conducted every 15 to 20 minutes.
  28. It is recommended that the first stop for a team check be just inby the fresh-air base.
  29. For teams using a compressed oxygen breathing apparatus, the captain usually notes each team member’s gauge reading at each rest stop and reports the lowest reading to the fresh-air base.
  30. "Tying in" is the process by which you systematically explore all crosscuts and adjacent areas as you advance.
  31. As the team advances underground, the captain takes the lead.
  32. It is important that the team pace its work so that it can return to the fresh-air base on time.
  33. As the team advances, the map man records what the team encounters by marking the information on a mine map.
  34. When reporting anything to the fresh-air base, be sure you are clearly and correctly identifying locations.LI VALUE=1>The team is responsible for choosing the exact sites within headings for building seals.
  35. Smoke causes a lack of orientation which may cause a team member to lose his/her sense of balance.
  36. Color, odor, and taste are physical properties that help to identify gases during barefaced exploration.
  37. Only detectors and chemical analyses can positively identify a gas.
  38. In order to maintain an airlock, one door of the airlock must be kept closed while the other is opened.
  39. Rescue teams should build an airlock so that the two stoppings are erected as close together as possible yet with enough space to allow room for the team and their equipment to fit in between.
  40. If the fresh-air base is underground, it should be located where it’s assured a fresh air travelway to the surface.
  41. The fresh-air base should be located where it’s assured positive ventilation and fresh air.
  42. Elevators should be tested before use following a disaster.
  43. As a team advances, it is important to stay in close contact with the fresh-air base to report team progress and to receive further instructions.
  44. In the event that rescue team communications fail, it can still communicate with the fresh-air base by tugging on the communication cable.
  45. When using the lifeline for communication, the attendant at the fresh-air base will acknowledge receiving a signal from the team by sending it back to the team.
  46. Team captains should inspect roof and ribs before the team members advance into the area.
  47. Teams should not travel in water deeper than knee deep (less in low coal).
  48. Hazardous areas should be marked to warn other teams that may enter the area after yours.
  49. Progress reports should include reports on roof and rib conditions and gas conditions.
  50. Coking or coke streamers, if encountered, should be reported in location and size.
  51. The time spent underground by a rescue team is usually limited to two hours or less.
  52. When looking for survivors, it is important to both look and listen for clues.
  53. When survivors are located, their location, identities, and condition should be reported immediately to the command center.
  54. When survivors are located, the location, time, and date should be marked on the team’s map and on the rib where they are found.
  55. When survivors are found, they should be transported to safety and fresh air as quickly as possible.
  56. The main objectives of exploration work during a mine fire are locating the fire and assessing conditions in the fire area.
  57. A self-contained breathing apparatus is a completely portable unit that supplies oxygen or air independently of the surrounding atmosphere.
  58. A team is a unit made up of individuals working toward a common goal.
  59. If a team member must return to the fresh-air base because of a problem, it is standard practice among teams for the entire team to go back with that person. No one should ever travel alone.

IV. Firefighting & explosions

  1. Electrical fires are "Class C" fires.
  2. "Class A" fires are best extinguished by cooling with water or by blanketing with certain dry chemicals.
  3. Burning wood is an example of a Class A fire.
  4. The recommended extinguisher for mine rescue teams is a dry chemical type that contains monoammonium phosphate.
  5. A monoammonium phosphate extinguisher is effective in fighting Class A, B, and C fires.
  6. Foam is useful only in fighting Class A and B fires.
  7. Carbon monoxide is a product of incomplete combustion of any carbon material.
  8. Opening of seals prematurely can cause a re-ignition of a fire or an explosion.
  9. Sufficient time should be allowed for a fire area to cool before it is unsealed.
  10. Smoke usually contains carbon monoxide and other toxic or asphyxiating gases produced by fires.
  11. One and one-half to two percent methane together with coal dust in air may be explosive.
  12. After a fire or explosion in a mine, rescue teams are usually needed to go into the mine to assess and re-establish ventilation.
  13. Indirect firefighting methods allow firefighters to remain a safe distance from the fire.
  14. Temporary seals are built before permanent seals are erected in order to seal off a fire area as quickly as possible.
  15. In mines where head coal (roof coal) is left, a fire will spread more rapidly.
  16. One hazard of heat during a fire is that it tends to weaken the roof, especially where head coal is left.
  17. Small hydrogen explosions, known as hydrogen "pops" are fairly common in firefighting.
  18. Fires can be attacked by the use of a foam generator from a distance of 500-1,500 feet.
  19. It is generally recommended that teams not travel through foam filled areas.
  20. One method of indirect firefighting is flooding the sealed fire area with water.
  21. Once an explosion has occurred, there is always the possibility of further explosions.
  22. Explosions, fires, and other disasters frequently result in weakened roof and rib conditions.
  23. Smoke causes a lack of orientation which may cause a team member to lose his/her sense of balance.
  24. Class B fires involve flammable or combustible liquids.
  25. Class D fires involve combustible metals.
  26. Before using a hand held extinguisher it must be checked for the type of fire you are fighting.
  27. If there is a sufficient amount of hydrocarbons in smoke, the smoke may be explosive.
  28. The most positive indicator of the origin of an explosion is the direction in which blocks have moved in or from stoppings across entries near intersections.
  29. The roof and ribs should be tested before extinguishing a fire.
  30. Coking or coke streamers, if encountered, should be reported in location and size.
  31. For a Class C fire (electrical), if power has been cut off to the burning equipment, it may be treated as a Class A or B fire.
  32. High volatile coal burns much faster than low or medium volatile coal.
  33. Hazards of direct firefighting are electrical shock or electrocution, toxic and asphyxiating gases, oxygen deficiency, explosive gases, heat, smoke, and steam.
  34. When fires are sealed in gassy or dusty mines, a thick coating of rock dust should be applied to the ribs, roof, and floor for several hundred feet outby the seals, and if possible, inside the seal, to reduce the chance of propagating a coal dust explosion.
  35. Frictional water loss can occur any time the water line is less than 2 inches in diameter.

V. Ventilation

  1. Before opening and traveling through any stopping inby which conditions are not definitely known, you should first erect a temporary stopping outby.
  2. A smoke tube is used to show the direction and velocity of slow moving air.
  3. When taking a reading with an anemometer, a commonly used method is to traverse the airway.
  4. An airlock consists of two doors or two stoppings with flaps or doors in them which are in close proximity to each other in the same passageway.
  5. The purpose of an airlock is to separate two different atmospheres while still permitting miners to enter and exit without mixing the atmospheres.
  6. Temporary stoppings built in a crosscut should be placed at least four to six feet into the crosscut in order that sufficient space is available to construct a permanent stopping.
  7. "Pogo sticks" are devices which may be used to erect temporary stoppings.
  8. Temporary seals should include provisions for collecting air samples from with the sealed area.
  9. Opening of seals prematurely can cause a re-ignition of a fire or an explosion.
  10. Progressive ventilation is the reventilation of a sealed area in successive blocks by means of airlocks.
  11. Direct ventilation is the reventilation of an entire sealed area at once.
  12. After a fire or explosion in a mine, rescue teams are usually needed to go into the mine to assess and re-establish ventilation.
  13. Temporary seals are built before permanent seals are erected in order to seal off a fire area as quickly as possible.
  14. Mine rescue teams may find it necessary to use line brattice to sweep noxious or explosive gases from a face area.
  15. Once ventilation has been re-established and fresh air. advanced, non-apparatus crews can take over the rehabilitation and cleanup effort.
  16. Rescue teams are responsible for assessing damage to the ventilation system.
  17. In situations too hazardous for teams to explore and reventilate safely, teams may be instructed to seal the area.
  18. Regulators are used in mine ventilation to regulate air flow to meet the individual needs of each air split.
  19. Overcasts are used to permit two air currents to cross without the intake air short circuiting to the return.
  20. The team is responsible for choosing the exact sites within headings for building seals.
  21. The basic principle of mine ventilation is that air always moves from high to low pressure regions.
  22. Ventilation controls are used underground to properly distribute air to all sections of the mine.
  23. In order to maintain an airlock, one door of the airlock must be kept closed while the other is opened.
  24. Rescue teams should build an airlock so that the two stoppings are erected as close together as possible yet with enough space to allow room for the team and their equipment to fit in between.
  25. If the fresh-air base is underground, it should be located where it’s assured a fresh air travelway to the surface.
  26. The fresh-air base should be located where it’s assured positive ventilation and fresh air.
  27. Urethane foam is an effective sealant when used around the perimeter of a seal.
  28. All permanent seals should be well hitched in the floor, roof, and ribs to improve their strength.
  29. It may be necessary to double or triple the thickness of the material in order to improve the effectiveness of the seal.
  30. Seals should be built at locations with good roof and even roof and ribs.
  31. gases, oxygen deficiency, explosive gases, heat, smoke, and steam.
  32. When fires are sealed in gassy or dusty mines, a thick coating of rock dust should be applied to the ribs, roof, and floor for several hundred feet outby the seals, and if possible, inside the seal, to reduce the chance of propagating a coal dust explosion.
  33. The formula for calculating air quantity is Q = A X V.
  34. To calculate air quantity using a smoke tube, the formula is the length of a measured airway divided by the time it takes smoke to travel that entry.
  35. The fan chart can determine when ventilation was disrupted or when an thermal incident occurred underground.