The Upper Flammability Limit (UFL) increases significantly with pressure, enlarging the flammability range.

The Upper Flammability Limit (UFL) increases significantly with pressure, enlarging the flammability range.

• A. True
• B. False
• C. Not enough data
• D. Only at very high temperatures

Answer: (A)

Flammability limits show which fuel–air mixtures can sustain a flame. When pressure goes up, the gas mixture becomes denser, which tends to boost the chemical reactions that keep a flame going. This allows the flame to persist even with more fuel present, so the upper flammability limit shifts to a higher concentration. Often the lower limit also shifts downward with higher pressure, so the overall flammable range widens. That’s why the statement that the UFL increases with pressure, enlarging the flammability range, is supported by how pressure affects combustion.

Flammability limits show which fuel–air mixtures can sustain a flame. When pressure goes up, the gas mixture becomes denser, which tends to boost the chemical reactions that keep a flame going. This allows the flame to persist even with more fuel present, so the upper flammability limit shifts to a higher concentration. Often the lower limit also shifts downward with higher pressure, so the overall flammable range widens. That’s why the statement that the UFL increases with pressure, enlarging the flammability range, is supported by how pressure affects combustion.