译文：
离心泵启动时要关闭出口阀，容积泵启动时不能关闭出口阀门。 因为离心泵启动时，泵的出口管路内还没有介质，因此还不存在管路阻力和提升高度阻力，在泵启动后，泵扬程很低，流量很大，此时泵电机（轴功率）输出很大（据泵性能曲线），很容易超载而导致泵的电机及线路损坏，因此启动时必须关闭出口阀，待电机达到额定转速后，再开启出口阀门才能使泵正常运行。 而一般容积泵本身都具有自吸能力。离心泵流量随压力改变很大，而容积泵流量随压力改变却很小，与离心泵的轴功率随扬程提高而减小的规律相反，容积泵的轴功率随压力的提高而增大。这要求在容积泵上和泵装置中必须设备安全阀，以防排出管路意外堵塞，造成泵压力过大，从而功率过大，使原动机或泵因超负荷而损坏。因此，容积泵启动时不能关闭出口阀门，直接启动即可正常运行。

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原文：
Centrifugal pump starts to close outlet valve, volumetric pump start valve does not shut down exports. Because the pump is started, the pump is still no media export pipeline, the pipeline does not yet exist a high degree of resistance and to enhance resistance, the pump starts, pump head is low, flow great, this time pump motor (shaft power) Output large (according to the pump performance curve), it is easy to overload caused by damage to the pump motor and wiring, so start the export valve must be closed until after the motor to achieve rated speed, and then open the outlet valve to the pump running. The general displacement pump itself has a self-priming capability. Centrifugal pump flow rate as a pressure change much, while the volume of pump flow rate as a pressure change was small, and the centrifugal pump shaft power decreases with the head of the law to improve the contrary, the volume of the pump shaft power with the pressure increase and increase. This requires a volume pump and pump installations in the necessary equipment safety valve to prevent accidental discharge pipe blockage, resulting in pump pressure is too large, and thus power is too large, so that the prime mover or pump damage due to overload. Therefore, the volume of exports can not be closed when the pump starts valves, normal operation can be started directly.