To provide a filter prolonged in a service period.
This filter 70 consists of filter media 72. The filter has higher affinity to filter blow than contaminants in fluid and the adhesion of the contaminants and the filter media 72 is smaller than the adhesion of the fluid and the filter media 72. The filter media 72 are more preferentially wet with the fluid than the contaminants. The filter media 72 are composed of fibers having predetermined surface rates and have the adhesion site smaller than the contaminants. The thickness of the filter media 72 is 0.7 to 2.0 mm. The filter media 72 are pleated to maximize the surface ranges and are formed to annular bodies having inner and outer circumferences 76 and 78. The annular bodies have at least five pleats per inch along the inner circumference 76. Reinforcing layers are disposed upstream and downstream to prevent the collapse of the surface filter media 72 during a filtration effect and blow back. The reinforcing layers are the screens witch are pleated and are formed respectively to the annular bodies. The pleated filter media 72 are held therebetween.
SCHWANDT BRAIN W
CADY DANIEL R
MULLINS GENE A JR
CURRIER W LEE
