A pump is a device specifically used to transport liquids or slurries from a lower level to a higher level or along horizontal pipelines.
It is a widely used general-purpose equipment in salt plants. Commonly used pumps include centrifugal pumps, mixed-flow pumps, axial-flow pumps, vortex pumps, pipeline pumps, reciprocating pumps, water ring pumps, screw pumps, gear pumps, and so on.
Different pumps are selected according to different needs to achieve our goals.
Specific speed is an important indicator for measuring pump performance.
The specific speed is included in some pump installation and operation manuals or on the models provided in the product samples.
The specific speed is a criterion used when discussing the similarity of impellers and determining pump characteristics and types.
In other words, the total head, flow rate, and rotational speed of a vane pump are the three basic parameters that determine the shape and size of the impeller.
Therefore, it can be said that:
1. The specific speed reflects the dominant characteristics of the pump, i.e., a low specific speed indicates a high head and low flow rate, while a high specific speed indicates a high flow rate and low head;
2. The specific speed reflects the shape of the impeller, i.e., a low specific speed corresponds to narrow and long blades, while a high specific speed corresponds to short and wide blades (as shown in the diagram);
3. The specific speed reflects the shape of the pump characteristic curves, based on which the O-H, O-N, and O-η curves can be plotted. The formula for calculating the specific speed is as follows:
ns = 3.65n(Q)^(1/2)/(H)^(3/4)
n: rotational speed (r/min)
Q: flow rate (m3/s)
H: total head (m)