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Pumbs
Published in Béla G. Lipták, Optimization of Industrial Unit Processes, 2020
In order for the pump to operate properly, the net positive suction head must be above the minimum practical suction pressure of approximately 10 PSIA (0.69 bar). The available net positive suction head (NPSHA) is given by Equation 3: NPSHA = P−Pv±Ph−(IvGN525)2+(IvC980Gd2)2
Application
Published in Ramnarayan Padmanabhan, Centrifugal Pump Clinic, 2017
If you refer to Fig. 1.14, you will note that the available NPSH is essentially the difference between the suction pressure at the pump centerline and the vapor pressure of the liquid at the pumping temperature. If the liquid pumped is boiling at the surface of the vessel, in other words, if Ps if equal to Pv, the available NPSH is equal to the static submergence over the pump centerline less the losses in the suction piping. If you pressurize the vessel, that is, if you increase Ps without changing the temperature of the liquid pumped, you will not be changing the liquid vapor pressure, and the available NPSH will be increased by the increase in Ps. In your particular case, the desired increase in available NPSH is 10 ft (required) less the 3 ft (available) or 7 ft. Expressed in psi, this is
Cavitation
Published in Getu Hailu, Michal Varchola, Peter Hlbocan, Design of Hydrodynamic Machines, 2022
Getu Hailu, Michal Varchola, Peter Hlbocan
It is worth noting that, because vapor pressure is a function of temperature, the value of NPSH depends not just on flow rate but also on liquid temperature. Figure 7.8 shows that the flow rate varies with the NPSH. It also shows the sketch of NPSH which decreases with increasing flow rate. The intersection between NPSH and NPSHR gives the maximum flow rate, which is the flow rate at which the pump can operate without cavitation. It should be noted that reducing flow rate on the suction side would result in reduced suction pressure, making the pump prone to cavitation. This is one reason why flow control valves are not installed on the pump’s suction side.
Influence of initial water content and strain rate on remolded yield stress in marine clay
Published in Marine Georesources & Geotechnology, 2022
Xiaobing Li, Jianpeng Chen, Xiuqing Hu, Hongtao Fu, Jun Wang, Xueyu Geng
Hong, Yin, and Cui (2010) observed that the compression curve of remolded soil exhibits an inverted S-shape, similar to natural soft clay. There is thus an inflection point similar to the yield stress of undisturbed soil that indicates the yield stress of remolded soil. The special pressure at this inflection point is called the “suction pressure.” When first observing this phenomenon, Mitchell (1993) pointed out that the liquid limits of all fine-grained soils correspond to about 6.0 kPa of pore water suction and about 1.7–2.0 kPa of shear resistance. In order to distinguish the approach used by Hong, Yin, and Cui (2010) from that used by Mitchell (1993), Zeng, Hong, and Cui (2015) named the inflection point the “remolded yield stress,” which has a corresponding void ratio of The compressibility of the soil is relatively small below the remolded yield stress. When the remolded yield stress is exceeded, the compressibility of the soil increases significantly. The results of the CRS consolidation tests of the Wenzhou clay in this study are shown for a strain rate of 3%/h and various water contents in Figure 2. Interestingly, when applying a strain rate of 3%/h, a phenomenon similar to ICL and EICL was also observed in the CRS consolidation experiment.
Condition monitoring and fault diagnosis of electric submersible pump based on wellhead electrical parameters and production parameters
Published in Systems Science & Control Engineering, 2018
Some formulas are used to deduce the relevance of the attempt and the reliability of the measurement method. The suction pressure of the pump is equal to the height of the liquid column above the suction inlet plus the sleeve pressure. The relationship can be written as where is the suction pressure of the pump, is the height of the liquid column above the suction inlet, and is the sleeve pressure. So the bottom hole flowing pressure can be expressed as where is the bottom hole flowing pressure, is the pump height, and is the average liquid density.