| 摘要 |
A concentric innermost tubular cylinder is located at the lower gable, and has an upwardly directed aperture issuing into an inner cylinder. This cylinder is concentric, located at the upper gable, and has a downwardly directed aperture. It is outside the innermost cylinder and above it. An outer, upwardly closed cylinder is located outside the cylindrical body, and has a downwardly directed aperture. The cylindrical body and the innermost cylinder have through holes in their lower parts, and the upper gable of the cylindrical body is provided with through apertures. When the outer cylinder is closed upwards, an air cushion can be arranged in the cylindrical part for regulation of the depth of insertion of the filter. |
