PURPOSE: To aim at reduction in the cost of production and promotion for a combined use, by constituting a pump body part with a stacking join of arbitrary number and diametral body blocks, while letting these upper and lower body blocks faucet joint together, and making a suction cover interchangeable.

CONSTITUTION: A conical type pump is designed to be free of attachment or detachment to or from a suction cover 8a, and a diffuser 9a is also set to a pump body part 7 in the same manner, while this pump body part itself is partitively constituted into plural pieces of upper and lower body blocks 7aW7c. An upper edge part 16 of the lower side body block 7b is made to faucet joint in a concave step part 25 of the upper side body block 7a and ten coupling flanges 12 and 13 are clamped with nuts 17 and 18 tight enough. Therefore, section of size of the pump body and the pump diameter may come to fruition as arbitrary ones among these plural body units are combined, thus manufacturing cost is reducible.