Patent ID: 8807915
Filing Date: 2014-08-19
Classification: F04D

Abstract:
1. A double casing type pump comprising: a plurality of impellers fixed to a rotation shaft; an inner casing shrouding the impellers; a throat diameter adjusting member; a replacing cover; and an outer casing forming at least a part of an outer housing of the double casing type pump, the outer casing shrouding the inner casing and having a suction opening and a discharge opening for fluid, wherein the inner casing and the outer casing have a space formed therebetween that communicates with the discharge opening, the inner casing has a working fluid passage configured to direct the fluid having a pressure that is lower than the fluid inside the space to a downstream side of the double casing type pump, the inner casing has a bypass hole that connects the space and the working fluid passage inside the inner casing, the throat diameter adjusting member is attached to the bypass hole, has a through-hole that defines a throat diameter of the bypass hole, and is configured to allow a return flow from the discharge opening to the working fluid passage via the space and the through-hole, the outer housing has a communication hole that communicates between the space and outside of the double casing type pump, the replacing cover is detachably attached to the communication hole to block the communication hole, and the throat diameter adjusting member is configured to be replaceable from the outside of the double casing type pump via the communication hole when the replacing cover is detached from the communication hole.