During leak testing, changes in pressure can occur due to changes in temperature, volume, and number of moles of the gas. Since parameters like pressure, volume, and amount of air are involved in this process, it is governed by the ideal gas law.
Read our white paper on the Ideal Gas Law and its effects on leak testing here: https://www.zaxisinc.com/ideal-gas-law-its-effects-on-leak-testing/