The fermentation process, enzyme catalysis process and cell tissue culture process of biopharmaceuticals require sterile and impurity-free purified air, or purified nitrogen, or purified carbon oxides and other inert gases or nutrient gases. The required compressed air needs to be sterilized and filtered. All gas sterilization filter elements have passed the 100% integrity test before leaving the factory. In the process of use, the integrity test of the filter element should also be carried out to ensure that the test value of the filter element is within the standard value range, to ensure that the filter element is in a good state and to achieve sterilization purpose.