The difference between the upper and lower flammable limits of a gas or vapor is called which range?

The difference between the upper and lower flammable limits of a gas or vapor is called which range?

• A. Flash point
• B. Ignition temperature
• C. Flammable/explosive range
• D. Vapor density

Answer: (C)

The range between the lower and upper flammable limits is called the flammable/explosive range. This is the concentration window in air where a gas or vapor can ignite or sustain combustion. Below the lower limit the mixture is too lean to burn, above the upper limit it's too rich to burn, and within that span ignition can occur. The width of this range (the difference between the upper and lower limits) is a critical hazard measure because it tells you how sensitive a vapor is to ignition in a given environment. This differs from flash point, which is a temperature metric for liquids; ignition temperature, which is the minimum temperature to ignite a vapor without a flame; and vapor density, which indicates whether a gas will tend to rise or sink in air.

The range between the lower and upper flammable limits is called the flammable/explosive range. This is the concentration window in air where a gas or vapor can ignite or sustain combustion. Below the lower limit the mixture is too lean to burn, above the upper limit it's too rich to burn, and within that span ignition can occur. The width of this range (the difference between the upper and lower limits) is a critical hazard measure because it tells you how sensitive a vapor is to ignition in a given environment. This differs from flash point, which is a temperature metric for liquids; ignition temperature, which is the minimum temperature to ignite a vapor without a flame; and vapor density, which indicates whether a gas will tend to rise or sink in air.