Introduction to the principle of differential pressure leak detector 1 Principle 2 Overview of Differential Pressure Sensor 3 Comparison between differential pressure detection method and direct pressure detection method

(1) The differential pressure testing method introduces the method of simultaneously applying air pressure to the test sample (workpiece) and the reference test sample (standard sample), measuring the change in pressure inside the workpiece caused by leakage using a high-sensitivity differential pressure sensor, and comparing it with the difference in pressure inside the standard sample to determine the leakage.

(2) The first step of the action stroke of the air leak detector is to start clamping the workpiece and seal it, and then input the start signal. The second step is to apply the test pressure to the test sample and the reference test sample through the pressurization stroke (CHG). The third step is to balance the stroke (BAL). Close the pneumatic control valves 1 and 2 inside the tester, and form a closed loop with the inspection part to detect the pressure difference between the test sample and the reference test sample (this stroke is the time for the pressure fluctuation to stabilize after the valve is closed, and it is also the stroke for detecting large leaks). The fourth step is to detect small leaks through the detection stroke (DET). The fifth step is to exhaust/complete the exhaust of air from the workpiece, and output a judgment signal for whether it is qualified or not

2. Overview of differential pressure sensor principle: The direct action of pressure on both sides is applied to the diaphragm of the differential pressure sensor. The diaphragm detects the small displacement caused by differential pressure as impedance changes and converts them into corresponding electrical signals for output. Due to the use of sealing liquid transmitted to the measuring element through the diaphragm, it is relatively difficult to damage the sensor under overpressure conditions and when the air contains impurities.