An explosimeter reading from 14% to 100% indicates what safety measure?

An explosimeter reading from 14% to 100% indicates what safety measure?

• A. No one enters the tank without a respirator
• B. No one enters the tank
• C. Entry allowed with a respirator
• D. Ventilate before entry

Answer: (A)

Explosimeter readings expressed as a percentage of the lower explosive limit show how close the atmosphere is to being flammable. A reading in the 14% to 100% range means there are enough flammable vapors present that breathing the air would be hazardous and could ignite if an ignition source is present. Because of that hazard, the correct safety measure is to ensure anyone entering wears a respirator appropriate for the vapors present. A respirator protects the worker from inhaling dangerous vapors while actions are taken to ventilate and reduce the concentration. Ventilation is important, but the immediate protection step this reading calls for is respiratory protection for anyone entering. Other options aren’t as appropriate given the reading: simply ventilating before entry doesn’t address the immediate need to protect the lungs from vapors, and blanket “no one enters” or allowing entry without protection would be too permissive for an atmosphere with a significant flammable vapor concentration.

Explosimeter readings expressed as a percentage of the lower explosive limit show how close the atmosphere is to being flammable. A reading in the 14% to 100% range means there are enough flammable vapors present that breathing the air would be hazardous and could ignite if an ignition source is present.

Because of that hazard, the correct safety measure is to ensure anyone entering wears a respirator appropriate for the vapors present. A respirator protects the worker from inhaling dangerous vapors while actions are taken to ventilate and reduce the concentration. Ventilation is important, but the immediate protection step this reading calls for is respiratory protection for anyone entering.

Other options aren’t as appropriate given the reading: simply ventilating before entry doesn’t address the immediate need to protect the lungs from vapors, and blanket “no one enters” or allowing entry without protection would be too permissive for an atmosphere with a significant flammable vapor concentration.