Views:7 Author:Site Editor Publish Time: 2019-09-07 Origin:Site
Calculation method of NPSH of slurry pump
The NPSHr is required for the pump (the pump NPSH is also called the necessary NPSH). The NPSH of the pump represents the pressure drop during the flow of the liquid from the pump inlet to the lowest pressure point, that is, the excess energy required to exceed the vaporization pressure per unit mass of liquid at the pump inlet in order to prevent the pump from cavitation. for
In the formula, the absolute average velocity (m/s) of the liquid before the inlet of Vo-leaf;
Wo The relative average velocity (m/s) of the liquid before the blade inlet;
G--gravity acceleration (m/s3);
Λ1 an absolute velocity drop coefficient, usually λ, = 1.0~1.2;
Λ--relative speed drop coefficient, also called blade cavitation coefficient.
Where wk - the relative velocity at the K point of the lowest pressure (m / s).
It is the relationship between the necessary NPSH of the pump and the available NPSH. It is also the discriminant for identifying whether the pump is cavitation, ie:
When NPSHa = NPSHr, the pump starts to cavitation corresponding to (Pk = pv);
When NPSHa<NPSHr, corresponding to (pk<pv), the pump is severely cavitation; only
When NPSHa > NPSHr, the pump has no cavitation corresponding to (Pk>pv).
Pump essential NPSH NPSHr and available NPSH are two different parameters. The pump NPSH is determined by the characteristics of the pump itself and is a parameter indicating the pump's own cavitation resistance. In order to improve the anti-cavitation performance of the pump itself, it is necessary to minimize the NPSH of the pump. The available NPSH is determined by the characteristics of the external suction device and is a parameter indicating the cavitation performance of the suction device. In order to improve the anti-cavitation performance of the device, it is necessary to maximize the available NPSH. However, structurally, the inhalation device and the pump itself are closely connected, so there is a connection between the two. For example, the available NPSH is expressed by the pressure and speed of the pump inlet. Under certain conditions (the pump starts cavitation). Time) The two values are equal. )we are china slurry pump manufacturer,we can guarantee quality.
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