Patent ID: 7198719

Claim:
A sealer holding structure for a spiral-type membrane element, comprising: (i) the spiral-type membrane element having an upstream end and a side circumference, said spiral-type membrane element being disposed inside an outer vessel; (ii) an outer-cover member that covers the side circumference of the membrane element and extends in an upstream direction from the upstream end of the membrane element; (iii) an annular sealer for sealing a space between the spiral-type membrane element and the outer vessel at the upstream end of the membrane element; and (iv) a sealer holding member for holding the annular sealer comprising a first annular portion, an annular projection, a second annular portion, and a third annular portion, wherein the first annular portion is engaged with an inner wall of the outer-cover member without contacting the side circumference of the membrane element; the annular projection stops an end of the outer-covering member; and the third annular portion is a second annular projection, and the second annular portion is defined between the annular projection and the third annular portion where the annular sealer is fitted, wherein the third annular portion includes a plurality of outer circumferential grooves with a partially lowered outer circumferential surface or a plurality of cut-outs with a partially removed annular portion.