Question 50Safety & Environmental - 1st Asst/Chief

70% to pass

The explosive range of a mixture of flammable vapors and air lies between the lower and upper explosive limits. These limits are specified as a percentage of _______________.

Athe lower limit of explosibility of the mixture
Bthe temperature of the flash point
Coxygen present to support combustion
Dflammable vapor by volume in air
AI Explanation

The correct answer is D) flammable vapor by volume in air. The explosive range of a flammable vapor-air mixture is defined as the range of concentrations between the lower explosive limit (LEL) and the upper explosive limit (UEL). These limits are specified as a percentage of the flammable vapor by volume in air. The explosive range is the concentration range where the mixture can ignite and explode if an ignition source is present. The other options are incorrect because they do not accurately describe what the LEL and UEL limits are based on. The limits are not based on the lower limit of explosibility, the temperature of the flash point, or the amount of oxygen present, but rather the percentage of flammable vapor in the air mixture.

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Official Resources
46 CFR Safety Equipment USCG Environmental Standards USCG National Maritime Center
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