Question 637Deck Safety70% to pass
The atmosphere in a tank is too rich when it is _______________.
AI Explanation
The correct answer is D) incapable of supporting combustion because the hydrocarbon vapor content makes the atmosphere above the UFL (Upper Flammable Limit).
The atmosphere in a tank is considered "too rich" when the hydrocarbon vapor content is above the upper flammable limit (UFL), making the atmosphere incapable of supporting combustion. When the vapor concentration is above the UFL, there is not enough oxygen present to sustain a fire or explosion, even if an ignition source is introduced.
The other options are incorrect because A) a noncombustible state does not indicate a "too rich" atmosphere, B) an atmosphere capable of supporting combustion is not considered "too rich," and C) an atmosphere below the lower flammable limit (LFL) is not "too rich" but rather "too lean" to support combustion.
Related Questions
#635 The spread of fire is NOT prevented by _______________.#636 Ventilation systems connected to a compartment in which a fire is burning are normally closed to prevent the rapid spread of the fire by _______________.#638 The atmosphere in a tank is too lean if it is _______________.#639 What is the generally accepted method of determining whether the atmosphere within a cargo tank is explosive, too rich, or too lean to support combustion? #640 The explosive range of petroleum vapors mixed with air is _______________.