Comparison of differential pressure method and pressure change method (pressure decay method)

The pressure change method (pressure decay method) directly displays the amount of pressure drop as the change in the pressure sensor output after the pressure is charged.

Scroll

	Differential pressure method	Pressure change method (Pressure decay method)
Sensitivity	Regardless of the test pressure, the differential pressure sensor can use the minute differential pressure range, allowing for highly accurate leak testing at all times.	A pressure sensor with a range that corresponds to the test pressure is used, so as the pressure increases, the resolution decreases and the leak detection sensitivity decreases.
Temperature	The effects of air temperature rise and temperature change are offset and reduced due to the comparison with the master. High resolution realizes high detection capability even with short detection time.	The effects of air temperature rise and temperature change appears as an error. Low sensitivity requires a longer detection time. If the test time is constant, a longer detection time limits the Pressurization and Stabilization time, resulting in a test with a large margin for error.
Effects of temperature and deformation	The initial stage of Pressurization includes many pressure fluctuations (errors) due to the effects of adiabatic and volume changes. The differential pressure method has a higher sensitivity than the pressure change method, allowing for a shorter Detection time. Even when the measurement time is limited, it can take longer Stabilization time than the pressure change method, making it possible to measure with less errors.
Compatibility	Even when the test pressure is changed, a common differential pressure sensor can be used.	To achieve maximum sensitivity, a sensor with a range matching the test pressure must be used.