The selection of self priming centrifugal pump refers to choosing an economical self priming centrifugal pump from various existing pumps according to the required liquid flow rate, head and liquid properties.

(1) Select the type of pump

According to the physical and chemical properties of the medium to be transported, the operating period of the process parameters and the structural characteristics of the pump, the type of pump is reasonably selected. When the conveyed medium is highly corrosive, it should be selected from the series of corrosion-resistant pumps. When the conveyed medium is petroleum products, an oil pump should be selected.

When choosing the type, it should be considered together with the number of units. Generally, only one pump is used in normal operation. In some special cases, two pumps can also be operated at the same time, but in any case, three pumps should not be used for material transportation in the device. In short, the number cannot be too much, otherwise the pipeline will be complicated and inconvenient to use, and the cost will be high. When continuous production and working conditions change greatly, in order to maintain normal production, appropriate consideration should be given to standby pumps.

(2) Estimate the flow and head of the pump.

When the normal flow, small flow and large flow are given in the process design, the larger flow can be directly used when selecting the pump; if only the normal flow of the device is given, an appropriate safety factor should be used to estimate the flow of the pump. When the required head value is given in the process design, it can be used directly; if the head value is not given and it is necessary, the elevation flow chart of the pump device is generally drawn first when estimating, indicating the position of the self priming centrifugal pump in the process, Elevation, distance, pipeline length and number of pipes, etc., calculate the flow loss. If necessary, leave a margin, and then determine the lift that the pump needs to provide.

(3) Select pump model

When the pump type is selected, plot the flow Q and head H values ​​on the series performance curve spectrum of this type of pump to obtain the coordinate point P. The intersection point P falls on the self priming centrifugal pump performance curve spectrum. In the quadrilateral (see the figure below), you can read the self priming centrifugal pump model on the quadrilateral. If the intersection point P does not just fall on the upper and lower sides of the quadrilateral, after selecting the pump, the method of changing the impeller diameter or working speed can be applied to change the performance curve of the pump so that it passes through the intersection point P. At this time, you should find out the characteristics of the pump when delivering water from the pump sample or series performance specification table for conversion. If the intersection point P does not fall in any quadrilateral of the working area, but is near a certain quadrilateral, it means that no pump can meet the working point parameters and make it work in a more efficient working range.