1.Combustion engine oil filter is located in the oil pump and the main oil path, in order to let enough oil flow to the engine, the pressure drop of the rated flow is not exceed the specified value. When the main engine choosing the oil filter, it needs to check the rated volume of the oil filter, whether it can fit the oil amount of the main oil path, besides, in the technical requirements of filter, the original resistance and filter should be tested in the rated flow , so the rated flow is the important parameter to measure the capacity of the filter.

 2. The by-pass valve of the filter

 When the pressure drop of the element is high, maintaining sufficient oil flow to the engine to avoid engine being damaged because of the deoiling. 

When the filter element works normally, the by-pass valve must be close. In order to limit the entering of the un-filtrated oil to the engine, usually the design of the by-pass valve is not to open under the regulated pressure drop, when the pressure drop is not overpass the regulated value, it is permitted to come through, there will be oil leakage volume that is not exceed the specified value and the oil leakage volume is regulated by the percent of the rated flow.

3.Filter back-pressure valve

Spin-on oil filter, it can be installed in horizontal or inverted. In the state of this installing, after the engine stops, the oil in the filter housing will fade gradually. When the engine starts again, only if make the filter housing filled with oil then the oil comes to the main oil path, then it cause the oil supply lag to the main oil path and thus cause the friction and wearing of each parts.

 So it needs to have enough oil in the filter housing. In order to prevent the loss of the oil inside the filter, it needs to set technical state that conforms to the requirements of the back-pressure valve.

 4. Pulse-fatigue strength: During the usage of oil filter, it will be attacked by the pressure thatin condition of cold start of the engine. So it needs to check the spin-on filter housing and the ability of sealing ring which bear the regulate times of high pressure attack, so that it can guarantee the reliability of the usage of the filters.

 5. The blocking lifetime of filters:  When the filter is in use, some impurities will be prevented from the outside of the element, with time going on, the impurities increased gradually, thus it increase the pressure drop and then finally form the element blockage, then the bypass-valve will open, and make the oil which is not filtrated to enter into the main oil path of the engine. In order not to make the oil leak during its working, usually it regards the 70% of its opening pressure as the finishing of the element.

 6. The high oil temperature resistance:  During the usage of the filter, it will go through the high temperature oil for a long time.  For the technical standard, it requires the filter to be soaked in the oil( the temperature is 135ºC) for 192hours, the element should not be glue-dropped, damaged and other parts should not be distorted permanently or damaged partly.

 7. High pressure drop:  When the filter is used for long time and blocked, it will suffer the p the high pressure drop. For standard, it requires the element should be no breakage, no perforation, glue-dropped under the pressure drop of 0.35 Mpa, the central tube should not be distorted.

 8. Static pressure breakage:  When using, the filter is likely to be attacked by the high oil temperature of the engine in special circumstance. It requires the filter’s housing should be no breakage of oil leakage under the pressure of 1.5 Mpa and keep for 1-5min.

9. The efficiency of filtration: The efficiency of filtration is the main project that evaluates the quality of the filters. Before the element is damaged, the efficiency will improve along with the using time. At present, Normally for the combustion engine, it requires the original filtration efficiency should be equal or greater than 60%.