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Values of specific speed less than 500 are associated with positive displacement pumps. As the specific speed increases, the ratio of the impeller outlet diameter to the inlet or eye diameter decreases. This ratio becomes 1.0 for a true axial flow impeller. The following equation gives a dimensionless specific speed:
The affinity laws are useful as they allow the prediction of the head discharge characteristic of a pump or fan from a known characteristic measured at a different speed or impeller diameter. The only requirement is that the two pumps or fans are dynamically similar, that is, the ratios of the fluid forced are the same.
SG is the specific gravity of the fluid (for water = 1), ΔP is the pressure drop across the valve (expressed in psi). In more practical terms, the flow coefficient C v is the volume (in US gallons) of water at 60 °F (16 °C) that will flow per minute through a valve with a pressure drop of 1 psi (6.9 kPa) across the valve.
Specific Pump Power (SPP) is a metric in fluid dynamics that quantifies the energy-efficiency of pump systems. It is a measure of the electric power that is needed to operate a pump (or collection of pumps), relative to the volume flow rate. It is not constant for a given pump, but changes with both flow rate and pump pressure.
Here and depend on the geometric parameters and the rotational speed of the pump and are assumed to be constant for the purpose of comparison. However, this simple linear relationship undergoes modification on account of various losses and a non-linear, decreasing H − Q {\displaystyle H-Q} relationship is seen in the pump characteristic curve.
The simplest inlet to a centrifugal compressor is typically a simple pipe. Depending upon its use/application inlets can be very complex. They may include other components such as an inlet throttle valve, a shrouded port, an annular duct (see Figure 1.1), a bifurcated duct, stationary guide vanes/airfoils used to straight or swirl flow (see Figure 1.1), movable guide vanes (used to vary pre ...
Warman centrifugal pump in a coal preparation plant application A pair of centrifugal pumps for circulating hot water within a hydronic heating system. Centrifugal pumps are used to transport fluids by the conversion of rotational kinetic energy to the hydrodynamic energy of the fluid flow. The rotational energy typically comes from an engine ...
If an NPSH A is say 10 bar then the pump you are using will deliver exactly 10 bar more over the entire operational curve of a pump than its listed operational curve. Example: A pump with a max. pressure head of 8 bar (80 metres) will actually run at 18 bar if the NPSH A is 10 bar. i.e.: 8 bar (pump curve) plus 10 bar NPSH A = 18 bar.