In production, it is often necessary to put forward requirements according to the process.Select pump type and matching motor.The selected pump is expected to have a wide working range, and the range of working conditions is an efficient working area.Easy operation and maintenance, stable performance, long and reliable life, good suction characteristics, less investment later, small size, light weight, low cost, easy to manage.The specific method of pump selection and the steps of pump selection are as follows:
Draw a schematic diagram of the process flow and list the process parameters, including physical properties of the medium (viscosity, density, saturated vapor pressure, corrosion, etc.), operating conditions (including suction and discharge level position, pressure, operating temperature, liquid volume, pipeline length, structure, altitude, etc.).
If the medium is water and can flow to the pump, use the regular centrifugal pump series.
Vertical centrifugal pump or horizontal centrifugal pump.
It is recommended to choose the new motor and pump body for convenient disassembly and maintenance of pipeline circulation pump.
The picture below shows the new vertical centrifugal pump motor and pump for easy removal
If the water level is lower than the pump self-priming height in 5 meters, then you can only choose a pump with self-priming ability.
For example: self-priming centrifugal pump if the medium is sewage, containing sundry, it is recommended to choose self-priming sewage pump products.
If the height of self-priming is more than 5 meters, or the pump inlet pipe is long, then it is recommended to use comay high suction self-priming pump.
The height of self-suction pump with high suction range is within 9 meters, and the horizontal distance can absorb about 300 meters.
More than the value then can only choose submersible pump series more appropriate.
The figure below shows kemai’s high suction self-priming pump with a self-priming height of 9 meters and a horizontal distance of 300 meters (the actual suction distance needs to be calculated according to the flow head).
If you want to choose a large flow, and weight, easy to move the pump, we recommend to choose the new type of large flow portable submersible pump.It has motor drive or hydraulic motor drive according to different requirements can be configured.
The following figure shows the large-flow portable permanent magnet motor submersible pump (400 cubic meters per hour, 8-10 meters head weight only about 36kg), and the large-flow portable submersible pump with cutting function can be customized.
Liquid has a certain viscosity, centrifugal pump pumping is not moving, it is recommended to choose diaphragm pump series or screw pump.
Can also use gear pump and CAM rotor pump.
As long as the medium can flow, the above types of pumps can be used.
If corrosive, it is recommended to choose pneumatic diaphragm pump, because the diaphragm pump body material has a variety of stainless steel or PP plastic, and PVDF material.
For the use of different media, viscosity is very large recommended low speed screw pump or CAM rotor pump better effect.
Metering pump is divided into diaphragm metering pump and plunger metering pump.
In the selection of the need to pay attention to, if the media is prohibited leakage, then please do not choose the plunger metering pump.
Because the plunger metering pump is the use of packing seal, the use of dripping phenomenon will occur.
Please change the diaphragm metering pump or the required pressure metering pump.
When the need to pump as air to reach a certain negative pressure, vacuum pump should be selected.
The calculated flow rate of the pump is 1.1 times the maximum or normal flow rate.
The hydraulic loss of the pipeline is estimated according to the pump installation diagram. The pump head is then determined by the Bernhard equation.
First according to the pump processing medium to determine which type of pump, and then according to the calculation of flow and head to choose the structure of the pump.
Then in the corresponding pump type general diagram, find the selected pump type, if the flow, head is not enough at the top and bottom edge of the quadrilateral.
It is necessary to change the pump speed or cutting impeller diameter to make h-Q performance curve just through the flow, head point.
If the calculated flow, head can not find a suitable pump (that is, flow, head is not in the appropriate quadrilateral, but in the vicinity of the quadrilateral).
Two pumps can be used in series or parallel or take throttle regulation to meet the requirements of the process, or choose other types of pumps.
When the specific selection of pumps, should also test the special requirements of the process, if you want the flow change when the head is basically unchanged, you can choose a flatter characteristic curve of the pump, in addition, should avoid the operation of unstable conditions.
After selecting the model of the pump, it is necessary to check whether cavitation occurs in magnetic pump, which can be determined according to Hg<[Hg] or Hs<[Hs] or NPSHa>NPSHr.
If the result is cavitation, the suction line of the pump must be changed or other measures to improve cavitation performance must be adopted to meet the cavitation characteristics.
If still cannot satisfy, can choose other type of pump only.
Calculate the shaft power of the pump according to the flow, head and efficiency (Q, H, Eta), calculate the motor power from the shaft power, select the motor.
