3. Must be a structure that repair and wash is easy. 4. Pipe Laying with the contiguous equipment (application equipment) must be easy. - If the location of nozzle is changed free, the Pipe Laying has a good structure. 5. Must be a structure to be maintained airtightness between a contacting part of element and a parallel state of strainer. 6. Element and Equipment Body must maintain the strength to be able to endure in the high-pressure-drop considering the internal, external pressure sufficiently.