The airtight detection equipment is calculated by the pressure drop of the sealed chamber and the volume of the chamber, and the size of the pressure drop is closely related to the detection pressure and detection time. Any change of parameters will directly affect the detection results. In the process of airtightness testing of products, some products have air inlets, which can be directly connected to the test tube to pressurize the product for airtightness leak detection. Another part of the products are completely sealed products, which do not have inflation ports. For the detection of such products, it is necessary to first customize a precise sealing mold that fits with the product, connect the instrument, and then put the product into the sealing mold for testing. When the test is started, the instrument will pressurize the sealing mold quantitatively. When the product does not leak, the pressure in the sealing mold is constant; When a product leak is detected, a part of the gas filled with a certain amount will enter the product, so the pressure of the product with a leak will be lower than that of the product without a leak during the test. This allows rapid detection of product leaks.

Several test indexes of air tightness testing equipment:

1、 Detection pressure

Whether the leakage of the workpiece is qualified shall be judged under the test pressure given in the corresponding standard. For leaks of the same size, when the detection pressure changes, the pressure drop caused in the same time will change. Similarly, for the tested workpiece with small leakage, the leakage amount under different test pressures will also be different.

2、 Detection time

The detection process of the airtight detection equipment is divided into four links: inflation, balance, detection and exhaust. Time setting is required for each link. Leakage detection can only be carried out after the gas reaches a stable state. Under ideal conditions, the longer the detection time is, the higher the detection accuracy of leakage is. However, a reasonable time range should be determined according to the actual situation in use to ensure efficiency.

3、 Detection interval

According to the ideal gas equation:

PV=nRT where:

P-pressure of ideal gas;

V - volume of ideal gas;

N - amount of gaseous substances;

T - thermodynamic temperature of ideal gas.

In order to improve the detection accuracy and efficiency of the airtight detection equipment and realize the detection automation, the current popular airtight detection method is the differential pressure method. If the tested container leaks, it will inevitably cause the loss of gas quality and pressure drop in the container, which will reduce the original air pressure in the container. By measuring the gas pressure drop in the container, the amount of gas leaking from the actual container can be deduced, so as to achieve the purpose of airtight detection.