泵性能曲线
泵性能曲线是泵制造商生产的重要图纸。泵性能曲线主要用于预测泵穿过泵的变化，随着流量的变化。但是，除了更改流量时，效率，功率，NPSH的差异也可以由制造商在泵性能曲线上表示。
It is important to be able to阅读并理解泵曲线用于选择，测试，操作和维护泵。
通常，泵性能曲线会带有有关以下几点的信息。
Variation of differential head Vs flow
This is the primary information reported in the pump performance curves and very important information regarding most of the pump calculations related to differential pressure across the pump. As shown in the sample performance curves, usually 3 curves of differential head Vs. volumetric flow are reported.
Differential head Δh is related to differential pressure ΔP by the equation, ΔP = ρgΔh.
- 差分头的曲线评级叶轮直径表示叶轮具有额定直径的差异头的变化，实际上将与泵一起提供。
- Variation of differential head with volumetric flow forMaximum Impeller Diameteris plotted for the impeller with the maximum diameter that can be accommodated within the pump. This impeller can be used in case flow through the pump is increased or if more differential head is required in the future, with the same pump.
- Variation of differential head with volumetric flow forMinimum Impeller Diameter为叶轮绘制，直径最小。如果将来减少了流量或差分需求，则该叶轮可用于较低的功耗。
Although the 3 curves are plotted for a wide range of volumetric flow rates, the actual operation is to be limited within theMaximum and Minimum allowable flow rates如样品泵性能曲线所示。泵制造商给出了最大和最小流量限制的值。
差分头轴（y轴）上的点，这3个曲线终止，代表关闭差分头对于特定的叶轮直径。对于正常的预期操作，额定叶轮直径的关闭差速头很重要。
It should be note that the pump curves for differential head Vs. volumetric flow rate are plotted for a particular liquid density. If in the future the process liquid or even just liquid density is changed, that effect has to be considered to finally determine the differential pressure. In such as case, revised volumetric flow should be calculated and located on the pump curve and corresponding differential head should be then determined from the curve for the appropriate impeller diameter. This differential head should then be used along with the changed liquid density to determine the differential pressure across the pump.
泵的效率
如上面的样品泵性能曲线所示，在泵性能曲线上，通常还报告了泵效率对体积流量的图。当理论泵送功率需求除以相应流动的效率，结果是泵轴功率要求。有关使用效率计算泵电源计算的更多信息，请参阅ld乐动体育appEnggcyclopedia的解决样本问题。计算出的泵轴电源必须由电动机提供。
The efficiency curve typically has a maximum within the allowable operating range. This maximum is also known as the最佳效率点（BEP）如样品曲线所示。正常操作应最好地完成此最佳效率点，以达到最低功率要求。
Sometimes a plot ofPump Shaft Power requirementis also done against the volumetric flow rate on the performance curves. This curve readily gives the value of power requirement for a particular flow rate.
NPSHR (Net Positive Suction Head Required)
每个泵都需要一定Net Positive Suction Head (NPSH), for safe and smooth operation and to avoid泵。泵制造商通过将它们绘制在体积流量上来提供这些值。从样本性能曲线中可以看出，NPSH的需求增加了体积流量的增加。在设计泵系统并定位泵时，必须始终确保可用的NPSH高于根据泵曲线的NPSH要求。有关可用计算NPSH的详细信息，请参阅Enggcyclopedia解决的样本问题。ld乐动体育app
How to read a pump curve
泵曲线通常用于不同的叶轮直径值。对于大型叶轮直径，您会得到更多的差分头。对于给定的叶轮尺寸，当将更多的流体推到泵中时，它将产生较小的差分头（鉴于机械和功率限制）。
我们can see that on the pump performance curve. For any given impeller diameter, pump generates the maximum differential pressure or differential head near the shut off point, when there is very little fluid getting pushed through the pump.
As the flow rate is increased, we move to the right of this graph. And you can find that for the same impeller diameter, differential head starts to drop as the flow is increased.
But, even as the diff. head drops down the resulting output given by the pump in terms of flow rate multiplied by differential head goes up because of increasing flow rate. As this happens, the pump also consumes more and more power to push more fluid while trying to maintain similar level of differential pressure (or differential head).
结果，有一个最佳效率点，其中泵可以以最高的输出功率 /输入功率比例运行。这一点被称为最佳效率点for that pump and clearly visible on“泵效率曲线”绘制在同一图表上，反对运行流量。
值NPSH必需（NPSHR）泵制造商还以同一图表上绘制的另一个图的形式提供。
这是一个更详细的帖子about reading and understanding the pump performance curves.
泵曲线的示例
不同的泵制造商的泵曲线图具有不同的格式。因此，有时泵曲线一开始会看起来有些混乱。有时，单个图表上会有多行，您可能不确定每行的含义。在这种情况下，始终查找每条曲线的标签。
例如，考虑以下泵曲线图。
There are multiple curves here, on a single chart. But the good thing is that they are properly labeled. The green curve clearly represents the variation of "head Vs flowrate". The head is maximum at zero flow and drops down as the flow is increased. Notably, the "head vs. flowrate" curve is only plotted for a single impeller size.
Further, there is another U shaped curve of brown color. This represents the variation of pump efficiency against the flowrate. Peak point on the efficiency curve is clearly marked on the chart as the -最佳效率点(BEP)。
最后，底部有一条橙色曲线，指示必需的NPSH(NPSHr) for different flowrates. As the flowrate increases, so do the frictional losses. Hence at NPSHr goes up with increasing flowrate.
But not all pump curves are so nicely labeled. For example, consider this pump curve chart.
在这种情况下，图表上有多个曲线，它们的标记不太明确。但是，如果您现在已经了解了不同类型的泵曲线，则可以轻松猜测顶部的多个平行曲线表示“头部VS流”。这些曲线中的每一个都用不同的泵叶轮直径标记为英寸，范围从7英寸到9.5英寸。显然，当您使用较大的泵叶轮时，差异头会增加。
然后，您还可以在图表底部看到一个向上的趋势曲线。那就是“ NPSHR vs流量”曲线。
值得注意的是，此图表上没有单独的U形效率曲线。但是，您仍然可以看到几乎没有跨“头部VS Flow”图的轮廓。这些是在“头部VS流”上绘制的效率轮廓。每个轮廓都标有％效率。您可以在所有轮廓的中心看到最大值接近80％。该中心是此泵曲线图的最佳效率点（BEP）。
More about pump performance curves
- 泵性能测试- is used for gathering the performance data, then used for plotting the pump curve.
- Cause of pump overloading- 借助泵曲线解释
- Theory and equations for centrifugal pumps
- Operation and maintenance of centrifugal pumps
