Maximum pump outlet pressure

When measuring stable pressure, the maximum operating pressure shall not exceed 2/3 of the range； When measuring pulsating pressure, the maximum operating pressure should not exceed 1/2 of the range ； When measuring high pressures, the maximum operating pressure should not exceed 3/5 of the range ；

Thank you very much. Generally, field pumps operate at their maximum pressure, which is two-thirds, right?

You’re welcome. In fact, the operators on site can simply ask the technical department to specify the upper and lower limits based on the actual situation where there is no pump connected to the cutting torch. We just follow what the technical department tells us to do; we don’t need to take any responsibility

This post was last edited by ls880828 on 2017-1-10 at 13:24. You have got the cause and effect order wrong. The pump – we will select one with the appropriate pressure level, along with the matching motor, based on the pressure you need. When you mention the upper limit of outlet pressure, it should be an inherent property of the pump; this is generally determined through experiments rather than calculation, as there are many factors that affect this system property. A centrifugal pump generates pressure by using rotational speed; flow rate is proportional to pressure. As long as the components can handle it and the motor has sufficient power, the impeller can rotate at its maximum speed without causing cavitation, and the pressure resulting from this is the theoretical upper limit for the outlet pressure of a centrifugal pump. But in reality, before such pressure is reached, the motor’s power is no longer sufficient, or the components become ineffective (for example, I’ve heard of cases where the impeller spun too fast and was thrown out of the pump, though no one was injured). A screw pump is a type of pump that can theoretically achieve infinite pressure (yes, infinite), so it only has a \"rated flow rate\" and a \"operating pressure\". Generally, pressure is inversely proportional to flow rate. The upper limit of pressure is usually determined by the setting pressure of the safety valve; of course, if no safety valve is used, then the upper limit of pressure depends on how high the power of the motor can reach. Since backflow occurs due to the screw clearance, the upper pressure limit is also related to the designed screw clearance. When you ask “how is it determined,” you are probably referring to how the maximum pressure of the pump is determined in practice? You need to ask our manufacturer; they usually tell you. If we need to change the operating conditions on site, our factory will check factors such as the remaining capacity of the motor, the impeller profile of the pump, and the clearance of the spiral sleeve, and then let you know whether it’s possible.

Thank you; neither the pump’s nameplate nor the motor indicates the maximum pressure limit

Generally, the nameplate will contain this information

You can go to the reference room or archive to look for the technical specifications or contract attachments related to this pump; they contain information on the maximum allowable operating pressure

For centrifugal pumps, if the speed remains constant, the Q-H characteristic curve of the pump does not change. The outlet pressure and flow rate at the operating point of the pump depend on the characteristics of the piping system; therefore, the upper limit of the pump’s outlet pressure is the highest point on its Q-H characteristic curve. The motor current is proportional to the motor power, which essentially represents the shaft power of the water pump. The shaft power of a water pump is equal to the product of the pump’s head and flow rate, divided by the pump’s efficiency. Therefore, under normal conditions (that is, when there are no defects in the pump), the motor current is at its maximum when the product of the pump’s head and flow rate reaches its maximum value.