(1)泵的极限工作范围是指图1- 39中由曲线1。2.3.6围成的区域EFGH.曲线1表示标准叶轮直径D2时的H-Q曲线，曲线2表示最小叶轮直径D。时的H一Q曲线，曲线3表示由最小连续流量[Qm.]确定出的相似抛物线.曲线6表示由最大极限流C[Qm确定出的相似抛物线。泵可以在极限工作范围内连续运行。最小连续流量[Qmin]是指泵在不超过标准规定的噪声、振动、温升下能够正常运行时的最小流量,一般由泵制造商提供。当泵的流量增加时,必需的汽蚀余量NPSH,也随之上升,出现汽蚀的可能性增加，同时轴功率上升很快，存在过载的可能。因此，一般规定最大连续流量[Qmx]小于在最高效率点流量QN的125%~1 35 %。
(2)泵的高效工作范围是指图1- 39中由A.B.C.D所围成的扇形阴影区域,泵在该区域内的任意一点工作均认为是合适的。A、B两点为标准叶轮直径D,时H-Q曲线上比最高效率点N效率7-低a7的等效率工况点。过A.B两点可以作出两条等效率切割抛物线4和5，并交最小叶轮直径D..时的H-Q曲线于C。D两点。关于单级渣浆泵、多级离心水泵、石油化工离心泵的效率,应符合GB/T 13007 2011 和GB 19762- 2007 的规定，一般规定泵工作时的效率与最高效率之间的差值4n应不大于7%。选泵时,运行工作点应落在此高效工作区内。一般离心泵样本给出的特性曲线就是这种切割高效工作区的四边形。
Working range of flow head of slurry pump
(1) The limit working range of the pump refers to the efgh. Curve 1 in the area enclosed by curve 188.8.131.52 in Figure 1-39 represents the H-Q curve of standard impeller diameter D2, curve 2 represents the H-Q curve of minimum impeller diameter D., curve 3 represents the similar parabola determined by the minimum continuous flow [QM.]. Curve 6 represents the similar parabola determined by the maximum limit flow C [QM.]. The pump can operate continuously within the limit working range. The minimum continuous flow rate [qmin] refers to the minimum flow rate when the pump is able to operate normally under the noise, vibration and temperature rise specified in the standard, which is generally provided by the pump manufacturer. When the flow of the pump increases, the necessary NPSH will also rise, and the possibility of cavitation will increase. At the same time, the shaft power will rise rapidly, and there is the possibility of overload. Therefore, it is generally specified that the maximum continuous flow [qmx] is less than 125% ~ 135% of the flow QN at the highest efficiency point.
(2) The efficient working range of the pump refers to the sector shadow area enclosed by a.b.c.d in Fig. 1-39. It is considered appropriate for the pump to work at any point in this area. A. Point B is the constant efficiency operating point with the standard impeller diameter D, which is 7-7 lower than the highest efficiency point n on the H-Q curve. Two equal efficiency cutting parabolas 4 and 5 can be made through point A.B, and the H-Q curve at the minimum impeller diameter D.. Can be intersected at point C.D. The efficiency of single-stage slurry pump, multi-stage centrifugal pump and petrochemical centrifugal pump shall comply with the provisions of GB / T 13007 2011 and GB 19762-2007. Generally, it is specified that the difference between the efficiency when the pump is working and the highest efficiency shall not be greater than 7%. During pump selection, the operating point shall be located in this efficient working area. Generally, the characteristic curve given by centrifugal pump sample is the quadrilateral of this cutting efficient working area.