What is the pressure increase per 1 degree temperature rise according to the rule of thumb?

• A. 2 psi
• B. 1 psi
• C. 0.5 psi
• D. 4 psi

Answer: (A)

When a sealed, rigid container holds a gas, its pressure rises as temperature increases because the gas molecules move faster and collide with the container walls more often. For a quick, practical estimate used in hazmat work, the rule of thumb is about 2 psi increase for every 1°F rise in temperature. This reflects the P ∝ T relationship (in Kelvin) applied as a convenient shortcut for field checks. For example, if a cylinder sits around 1000 psi and the temperature goes up by 10°F, you’d estimate roughly a 20 psi increase to about 1020 psi, keeping in mind that actual values can vary with the gas type, initial pressure, and fill level.