Patent ID: 7255722

Claim:
A gas filter for removing oil mist from a gas comprising a cylindrical case and a filter element provided inside said cylindrical case, an inlet hole and an outlet hole being formed in said cylindrical case, the gas filter having a structure such that said filter element comprises a filtration portion formed to have a cylindrical shape; said filter element is provided inside said cylindrical case so that the inside of said cylindrical case is divided into an inner peripheral space surrounded by the inner peripheral surface of said filtration portion, and an outer peripheral space surrounded by the outer peripheral surface of said filtration portion and the inner surface of said cylindrical case; said inlet hole is formed in said cylindrical case so as to communicate with said inner peripheral space, said outlet hole is formed in the upper portion of said cylindrical case so as to communicate with said outer peripheral space, gas introduced from said inlet hole into said inner peripheral space is caused to pass through said filtration portion, outflow into said outer peripheral space and outflow to the outside from said outlet hole, and oil mist contained in said gas is separated and removed by said filter element, wherein said filtration portion is composed of only two layers of only two filtration materials being a first layer of a first filtration material formed to have a cylindrical shape with an inner cylindrical surface communicating with said inner peripheral space and a second layer of a second filtration material formed to have a cylindrical shape in intimate contact with the outer peripheral surface of said first filtration material and with an outer cylindrical surface communicating with said outer peripheral space so that the gas passes initially through said first filtration material and subsequently through said second filtration material; said first filtration material is made of glass paper and said second filtration material is made of a nonwoven fabric; and wherein a base material of said nonwoven fabric is any of PET, PE, PP, rayon, cotton, and Nylon and wherein: said filter element is composed of a cylindrical inner tube having a plurality of orifices formed therein, said first filtration material being wound tightly around the outer peripheral surface of said inner tube, and said second filtration material being wound tightly around the outer peripheral surface of said first filtration material, and, so that the first filtration material can be wound a preselected different number of times to provide a layer of different thicknesses and the second filtration material can be wound a preselected different number of times to provide a layer of different thicknesses to adjust the filtration efficiency and the pressure drop.