In a tightness test, which factor can affect accuracy due to physical properties of the gas?

In a tightness test, which factor can affect accuracy due to physical properties of the gas?

• A. The color of the test labels
• B. The brand of the tank
• C. Temperature changes affecting gas density
• D. The time of day

Answer: (C)

Temperature changes affecting gas density is the factor that can affect tightness-test accuracy because gas behavior follows PV=nRT. In a tightness test, you’re relying on a relationship between pressure, volume, and the amount of gas. If the temperature shifts, the pressure inside the tank changes even without any leak, and the gas becomes more or less dense. This alters the observed rate of pressure decay (or the stabilized pressure), which can make a leak seem bigger or smaller than it really is if temperature isn’t controlled or compensated. The other options don’t influence the gas properties in the same way: label color and tank brand don’t alter the physics, and time of day isn’t a physical property of the gas (though temperature can vary with time).

Temperature changes affecting gas density is the factor that can affect tightness-test accuracy because gas behavior follows PV=nRT. In a tightness test, you’re relying on a relationship between pressure, volume, and the amount of gas. If the temperature shifts, the pressure inside the tank changes even without any leak, and the gas becomes more or less dense. This alters the observed rate of pressure decay (or the stabilized pressure), which can make a leak seem bigger or smaller than it really is if temperature isn’t controlled or compensated. The other options don’t influence the gas properties in the same way: label color and tank brand don’t alter the physics, and time of day isn’t a physical property of the gas (though temperature can vary with time).