| 摘要 |
A filtration apparatus comprises a filter element in the form of a helical coil tension spring (20) suspended freely from one of its ends. The spring rate of the wire, from which the coil is wound, varies progressively along the length of the coil, such that the adjacent turns of the coil are held in contact with each other with a contact pressure which is uniform along the length of the coil. A machine is also disclosed, which may be used to make the filter element. |
