Developed by a pump

The total head developed by a pump is composed of the difference between the static, pressure and velocity heads plus the friction entrance and exit head losses for... 

A set of curves for h, rj, and P as a function of Q are shown in Figure 8.25 from which it is seen that when die pump is operating near optimum conditions, its efficiency remains reasonably constant over a wide range of flowrates. A more general indication of the variation of efficiency with specific speed is shown in Figure 8.26 for different types of centrifugal pumps. The power developed by a pump is proportional to Qghp ... 

The purpose of a centrifugal pump is to increase the pressure of a liquid in order to move it through a piping system. The pump is driven by a motor, which must provide sufficient power to operate the pump at the desired conditions. You wish to find the pressure developed by a pump operating at a flow rate of 300 gpm with an oil having a specific gravity (SG) of 0.8 and a viscosity of 20 cP, and the required horsepower for the motor to drive the pump. The pump has an impeller diameter of 10 in., and the motor runs at 1200 rpm. 

The feet of head developed by a pump is affected by the volume of liquid pumped. Figure 23.10 is a typical pump curve. As the flow of liquid from a centrifugal pump increases, the feet of head developed by the pump goes down, as does the pump discharge pressure. 

Whenever the inadvertent or unauthorized starting of a piece of driven equipment will create a hazard for inspection or maintenance personnel, it is important to disable that equipment while work is being performed. The hazard might be strictly mechanical, as in contact with rotating machinery, or partly chemical, as in a release caused by the pressure developed by a pump or compressor. 

Understanding the effects of solids on centrifugal pumps has been a slow process. Fairbanks (1941) developed a theory to correlate the head developed by a pump for a slurry mixture with the volumetric concentration and specific gravity of the solids. He explained that the fundamental Euler equation could be modified to account for the density and flow rate of the mixture as ... 

Viscosity must be taken in account when pumping viscous slurries. Viscosity reduces the efficiency of pumping and the head developed by a pump (Figure 8-43). The Hydraulic Institute Standards provides correction curves for viscous fluids pumping, but warns against extrapolating to other pumps or fluids. The Institute does not publish curves for viscous slurries. 

One of the most efficient implementations of the slurry process was developed by Phillips Petroleum Company in 1961 (Eig. 5). Nearly one-third of all HDPE produced in the 1990s is by this process. The reactor consists of a folded loop with four long (- 50 m) vertical mns of a pipe (0.5—1.0 m dia) coimected by short horizontal lengths (around 5 m) (58—60). The entire length of the loop is jacketed for cooling. A slurry of HDPE and catalyst particles in a light solvent (isobutane or isopentane) circulates by a pump at a velocity of 5—12 m/s. This rapid circulation ensures a turbulent flow, removes the heat of polymeriza tion, and prevents polymer deposition on the reactor walls. 

Whereas the total dynamic head developed by a centrifugal, mixed-flow, or axial-flow pump is uniquely determined for any given flow by the speed at whicdi it rotates, positive-displacement pumps and those which approach positive displacement will ideally produce whatever head is impressed upon them by the system restrictions to flow. Actually with slippage neglecTed, the maximum head attainable is determined by the power available in the drive and the strength of the pump parts. An automatic relief valve set to open at a safe pressure... 

This is the pressure at the pump discharge nozzle as measured by a gauge. It is equal to the suction pressure plus the total pressure developed by the pump. 

The general operation of a centrifugal compressor is like a centrifugal pump, except that the fluid is compressible. Theoretically, the head developed by a centrifugal impeller or wheel is the same regardless of the characteristics of the... 

Another centrifugal pump classification is whether the pump is a single-stage pump (the pressure head is developed by a single impeller) or a multistage pump (the pressure head is developed by two or more impellers). 

Sand with a mean particle diameter of 0.2 mm is to be conveyed in water flowing at 0.5 kg/s in a 25 mm internal diameter horizontal pipe 100 m long. Assuming fully suspended flow, what is the maximum amount of sand which may be transported in this way if the head developed by the pump is limited to 300 kN/m2 ... 

The virtual head developed by the pump is therefore independent of the density of the fluid, and the pressure will thus be directly proportional to the density. For this reason, a... 

The performance of a centrifugal pump is characterised by plotting the head developed against the flow-rate. The pump efficiency can be shown on the same curve. A typical plot is shown in Figure 5.10. The head developed by the pump falls as the flow-rate is increased. The efficiency rises to a maximum and then falls. 

The pressure developed by a centrifugal pump depends on the fluid density, the diameter of the pump impeller, the rotational speed of the impeller, and the volumetric flow rate through the pump (centrifugal pumps are not recommended for highly viscous fluids, so viscosity is not commonly an important variable). Furthermore, the pressure developed by the pump is commonly expressed as the pump head, which is the height of a column of the fluid in the pump that exerts the same pressure as the pump pressure. 

The pressure developed by a centrifugal pump for Newtonian liquids that are not highly viscous depends upon the liquid density, the impeller diameter, the rotational speed, and the volumetric flow rate. 

The total head Ah developed by a centrifugal pump at a particular capacity Q is independent of the liquid density. Thus the higher the density of the liquid, the higher the pressure AP developed by the pump. The relationship between AP and Ah is given by equation 4.10... 

The first observation of the stimulated Raman effect was reported by Woodbury and Ng 215) j e effect was then thoroughly studied by several authors 216-218) and its theoretical background developed 219.220) (see also the review articles by Zubov et a/.22D). The stimulated Raman effect can be described as a parametric process where the coupling between a light wave at the Stokes frequency (Os and an optical phonon (vibrational wave) at cOy is produced by a pump field at col = (Oj + ojy. 

Answer The power demand will go down to 60 Amperes. Amp(ere)s are a form of electrical work. The units of work are foot-pounds. The feet of head developed by the pump is not affected by the specific gravity of the liquid. But the weight of liquid pumped is proportional to the specific gravity. If the specific gravity drops by 40 percent, and the liquid volume (GPM) stays constant, then the pounds lifted by the pump, drops by 40 percent and so does the electrical work. 

The cause of this odd behavior is that the water level in the sump had dropped. A layer of oil with a specific gravity of 0.70 had been drawn into the suction of the pump. The feet of head developed by the pump had not changed. But a pump s discharge pressure and the amperage load on the motor driver is proportional to ... 

Kikkoman Corp., a soy sauce making company, developed an automatic chemical composition analyzer of soy sauce (Figure 9) [16]. The analyzer consists of an InfraAlyzer 400 or InfraAlyzer 500, a temperature controller, an automatic sampler and pumps. A certain amount of soy sauce collected by the automatic sampler is sent to the NIR analyzer at a constant flow rate by a pump through a temperature controller at 20°C. NIR measurement is made automatically. After the NIR measurement, the sample cell and tube are washed with cleansing liquid. It takes about 3 minutes to analyze one sample including washing process. 

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