The so-called pump selection calculation is actually estimated (many of the calculation formula itself is estimated), the estimated sub-detailed consideration of some of the more accurate calculation. In particular, the above mentioned resistance can be applied when the design flow is near the rated flow of the equipment, and more often the rated flow, which often exceeds the equipment. Similarly, water pipe water flow calculation is recommended, check the table to take resistance value. Pump head on the issue of excessive. Design of the pump head is too large, will enable the wealthy head in exchange for increased traffic, increased traffic makes the pump noise. In particular, the increase in traffic also makes the pump motor load increases, the current increases, heat increases, "change countless times bearing" or trivial matter, there is a great possibility to burn the motor. In addition "pump outlet pressure is only 0.22 MPa" can explain what? Pump import and export pressure is the key issue. For example, the open system pump on top of 100 meters, the outlet pressure is 0.22MPa, this system will pump on the ground to the top of 100 meters to send, the outlet pressure is 0.32MPa it!
