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1.将具有一定扬程的离心泵(如3B33泵或西农328泵,泵、管路及附件都无毛病)按图1所示的方法安装,虽然经计算几何吸上高度符合泵铭牌要求,但为什么往往吸不上水呢? 使用水泵时,应当使水泵在其工况区内安全运行.泵铭牌上规定的允许吸上真空高度〔H_S〕,是指泵在额定点(额定流量、规定转速,大气压760毫米水银柱、水温20℃、清水)运行时的数值,若泵流量或转速及使用条件发生了变化则〔H_S〕也随之改变.每台泵都有一定的使用范围(称工况区).图1的安装方法,对于具有一定扬程的离心泵来说,泵的流量已大于泵工况区内的流量,可见这种安装是不合理的,因此吸不上水来.这是为什么呢? 〔H_S〕随着流量的增加而降低.当流量大于额定流量时〔H_S〕降低;小于额定流量时〔H_S〕升高.例如:3 B33泵在小流量边界点时〔H_S〕为6.7米,在额定流
1. Centrifugal pump with a certain head (such as 3B33 pump or pump 318, pump, piping and accessories without problems) according to the method shown in Figure 1 installation, although calculated by the geometric suction height to meet the pump nameplate requirements, However, why not always absorb the water? The use of water pumps, the pump should be safe operation in its working area. The pump nameplate to allow suction on the vacuum height [H_S], is the pump rated point (rated flow, the provisions of Speed, atmospheric pressure 760 mm mercury column, water temperature 20 ℃, water) running time value, if the pump flow or speed and conditions of use have changed [H_S] also will change. Each pump has a certain range of use Working area). Figure 1 installation method, for a certain lift centrifugal pump, the pump flow is greater than the flow rate of the pump working area, we can see that this installation is unreasonable, so can not absorb water. 〔H_S〕 decreases when the flow rate is greater than the rated flow rate; 【H_S〕 rises when the flow rate is less than the rated flow rate. For example: 3 B33 When the pump is at the low flow rate boundary point 〔H_S ] Is 6.7 meters at rated flow