Page 83 - Know and Understand Centrifugal Pumps

Know and Understand Centrifugal Pumps

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Figure 6-14 - -
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discharge head. It makes for a small piece of iron that packs an amazing
punch. Regenerative turbine pumps are found on industrial high-
pressure washers and enjoy a well-earned reputation as a feed water
pump on package boilers.

Convent ion a I i m pe I I ers
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However, most conventional pump impellers receive the fluid into the
impeller eye, at the center or inside diameter of the impeller. There are
single suction impellers, and dual or double suction impellers with two
eyes, one on each side. Dual suction impellers are mostly specified for
low NPSH applications because the eye area is doubled (it can receive
twice as much fluid at a lower velocity head). Dual suction impellers arc
mostly found on split case pumps where the shaft passes completely
through the impeller. But they can also be found mounted onto the
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end of the shaft in some special pump designs.

Suction specific speed, Nss ~~__
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The way that a pump receives the liquid into the impeller determines
the available combination of discharge flow and head that the pump can
generate. Essentially, it determines the operating window of the pump. 1