The differential pressure leak detection method is a detection method that uses the gas flow formula to calculate the leakage amount through the change of pressure in the container.The leakage of a closed container will inevitably cause the loss of gas mass in the container, which will depressurize the original pressure in the container. Therefore, the actual amount of gas leaked from the container can be calculated by measuring the decrease in gas pressure in the container. The working cycle of air tightness testing by differential pressure method includes 4 processes, namely, inflation process, balancing process, detection process and exhaust process.

This working principle is shown in the figure:

The direct pressure leak detection method is to fill the workpiece under test with a set pressure of gas, open the valve to inflate, and close the valve to stabilize (that is, the gas fills the workpiece and is evenly distributed), detects the pressure drop value within a certain time interval, and calculates the leakage amount based on the gas state equation.

There is not much difference in the detection accuracy between the two, but the detection methods are different.The cost of using the differential pressure leak detection method is relatively higher than that of the direct pressure leak detection method, and the detection time is also longer. Currently, the direct pressure side leakage method is more popular in the market.

Working principle diagram: