Pump Type Follows:

Monday, April 27, 2009

Volute Pump

A variety of wet pit pumps are available. The liquid pumped, be it clean water, sewage, abrasive liquids or slurries, dictates whether a semi open or an enclosed impeller will be used, whether the shafting will be open or closed to the liquid pumped, and whether the bearings will be submerged or located above the liquid.

A single volute pump with a single suction enclosed nonclog impeller, no pump-out vanes or wearing ring joints on the back side of the impeller, and enclosed shafting. The pump is design to be suspended from an upper floor by means of a drop pipe and for pumping sewage or other solid laden liquids. To seal against leakage along the shaft at the point where it passes through the casing, a seal chamber or a stuffing box is provided.

In most application these volute pumps have been replaced with vertical wet-pit pump with the stuffing box/seal chamber in the discharge head. This pump is suitable for pumping heavy concentration of solid material (such as sludge or slurries) or in certain food processing application, but other type of impeller can be substituted. Pumped liquid leakage from casing is relieved back to the suction through holes in the support pipe. The seal chamber or stuffing box at the driver floor elevation is used only when gas tight construction is desired. The lower and any intermediate sleeve bearing are grease-lubricated as shown, but gravity feel oil lubrication is also available in other design. The upper anti friction thrust bearing is grease-lubricated. A solid shafts motor and flexible shaft are used.

An interesting design of the wet-pit pump uses a single stage, double suction impeller in a twin volute casing. Because the axial thrust is billings are externally lubricated, either with oil or with water. The lower bearing its lubricated from an external pipe connection.

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