An explosimeter reading of 100% or above indicates what action?

An explosimeter reading of 100% or above indicates what action?

• A. Entry with respirator is required
• B. Entry allowed without any precautions
• C. Entry is permitted after ventilation
• D. No one enters the tank

Answer: (D)

When a gas detector shows a reading of 100% or more of the LEL, the atmosphere is within the explosive range and can ignite with a source. That makes entry into the space unsafe; ignition hazards are present and cannot be controlled by PPE alone. The proper action is to keep people out of the tank and address the hazard by isolating or ventilating the space until the reading drops to a safe level, then recheck before any entry is permitted. Other options assume entry can proceed with some precaution or after a single ventilation step, but at 100% LEL the risk is high enough that no entry should occur until measurements indicate the atmosphere is below the safe threshold.

When a gas detector shows a reading of 100% or more of the LEL, the atmosphere is within the explosive range and can ignite with a source. That makes entry into the space unsafe; ignition hazards are present and cannot be controlled by PPE alone. The proper action is to keep people out of the tank and address the hazard by isolating or ventilating the space until the reading drops to a safe level, then recheck before any entry is permitted.

Other options assume entry can proceed with some precaution or after a single ventilation step, but at 100% LEL the risk is high enough that no entry should occur until measurements indicate the atmosphere is below the safe threshold.