Thread Content
Making the right choice of fluid handling equipment is knowledge that every designer needs to master. As the core equipment for conveying and lifting, chemical pumps are ubiquitous in chemical engineering. Therefore, it is also important to know how to choose the type of pump! Generally, when selecting a pump (magnetic pump, insulated magnetic pump, high-temperature magnetic pump, chemical shielded pump, diaphragm pump, etc.), we ask the user how much flow increase is required. If the traffic cannot be determined, the correct choice cannot be made. Many users, before purchasing a water pump, assume that a pump with a higher head can achieve a wider range of heads even when the actual head is lower. In this misleading interpretation, when you buy a pump, its head is very high. In fact, for centrifugal pumps, once the pump type is determined, its power consumption is proportional to both the actual pump and the flow rate. When the operating pressure of the pump is low, the flow rate increases ； As a result, the current is higher, the flow rate is lower, and the power consumption is lower. Instead, lower lift, higher flow rate, and higher power consumption. Therefore, to prevent the motor from overloading, it is generally required that the actual rated head of the pump be no less than 60%. Therefore, when a high-head pump is used at a low head, it is easy for the motor to overheat, and in severe cases the motor can be damaged. For use in emergency situations, it must be regulated through the outlet valve installed on the water outlet pipe. Normally, a self-acting control valve (or methods such as using wooden blocks) can be used to reduce the outlet flow and prevent the motor from overloading. Pay attention to the motor’s temperature. If the motor overheats, a low outlet flow rate or timely shutdown can prevent the motor from being damaged. Some users force a reduction in flow by lowering the power supply voltage, which increases the motor load. On the contrary, the outlet pipes of the units in centrifugal pump irrigation stations are equipped with valves to reduce the load on the motor. The valve should be closed before the pump stops, and gradually opened after the pump starts, to avoid overcurrent during startup. It should be installed in this way: the low-head pump is placed in front of the high-head pump, that is, the water output from the low-head pump is sent to the inlet of the high-head pump. One issue is that the outlet pressure of a low-head pump cannot exceed the upper limit of the inlet pressure of a high-head pump; otherwise, overpressure may occur leading to leakage.