Principals when select a centrifugal pump2013-07-30
The following principals should be satisfied when selecting a centrifugal pump:
1. Must reach the demands of flow, lift and transport fluid properties claimed by production engineering.
2. A centrifugal pump should have good suction performance and reliable tightness.
3. A centrifugal pump should have a wide efficient working area to ensure running economically when adjusting fluid flow.
4. Based on satisfying basic property, a centrifugal pump should be compact structure and low-cost.
5. Other special requirements, such as ex-proof, resistant to corrosion, etc.
Ways and steps to select a centrifugal pump
1. List basic data
List basic data according to engineering conditions, including physical property (such as density, viscosity, corrosion, saturated vapor pressure, etc), operation conditions( such as operating temperature, both sides of inlet and outlet tank pressure and pressure inside the tube, handling capacity, etc) and the situation of the pump (such as environment temperature, altitude, device conditions and vertical height from the equipment inside fluid level when discharging to the center line of the pump and the equivalent length of pipe, etc).
2. Estimate flow and lift of a pump
When engineering design provides minimum flow, normal flow and maximum flow, one can select the maximum flow, if only provided with a normal flow Qp, an appropriate safety ratio should be adopted to estimate flow, Q=(1. 05~1. 10Qp) is adopted in common. When the maximum lift is provided, it can be adopted directly; If a lift need to be estimated, a three-dimensional flow chart of a pump device should be drew first indicating the position, height, distance, pipe length and pipe valve quantities of the centrifugal pump to determine the head ratio, H=(1. 05~1. 15)Hp is adopt commonly.
3. Choosing type and model of a pump
Decide on the basis of the property of transported medium to determine the type of a pump, then choose the model according to the flow and lift that engineering requested.
4. Check the performance of a pump
In the actual production process, in order to ensure normal operation and avoid erosion, one should check the pump performance according to process requirements. If not satisfied, must choose other pumps or change the position of the pump or take other measures.
5. Calculate the pump shaft power and drive power
Pump shaft power can be calculated according to transported medium and working point parameters Q, H, μ, n, 10%~15% reserve power should be taken into account when choosing the power of driving machine.