1. Flow resistance characteristics
The pressure difference generated before and after the filter at the rated flow rate is also the pressure loss value, and the smaller the value, the better the filter passability. The rated flow rate is generally taken as follows: if the user provides the design flow rate of the oil pump or the measured flow rate of the new oil pump, the filter flow rate can be 50-60% of the flow value of the oil pump. Some users also provide the filter designer with the design flow of the main oil passage of the internal combustion engine. In this case, the flow value of the filter should be set at 1.5-2.0 times the design flow of the main oil passage. This is because with the normal wear of the internal combustion engine energy, the flow rate of the main oil passage will increase accordingly to maintain normal oil pressure. It is generally required that the original resistance of the full-flow filter should not be greater than 0.025 mpa when passing the rated flow rate.

2. Filtration efficiency measured by the new filter element
Define the filtration efficiency measured on the new filter element, called the original filtration efficiency, the requirement "=60%." When determining the original filtration efficiency, the oil containing a certain amount of a certain size of AC ash is passed through the filter at a rated flow rate of about 10% or more than 45Kpa pressure, and after washing for several times, the impurity content in the filtered oil can be analyzed to calculate the original filtration efficiency. The results obtained by different particle sizes of AC ash are different.

3. Life characteristics
A new filter element from the beginning of use to plugging, that is, the pressure difference between the front and back of the filter element reaches 70% of the filter bypass valve opening pressure. When the filter life is measured on the clogging life test bench, the test impurities should be added to the test oil at a constant speed to simulate the clogging under the actual use conditions of the filter element at double speed. During the test, the pressure difference before and after the filter is recorded every 20 or 30min. When the pressure difference reaches 70kpa, the test is terminated. The number of hours up to this time or the total amount of test impurities added can be used as an indicator to evaluate the life of the filter. Represents the change in filtration efficiency of the filter during the plugging process. The cumulative efficiency reflects the filter element performance more comprehensively than the original efficiency.