Centrifugal pumps components

FIGURE 11-2 Centrifugal pump components (courtesy Oil Gas Journal)... 

PPS is well suited for the manufacture of mechanically and thermally highly stressed moulded parts. In machine construction and precision engineering PPS is used for various components such as pumps, valves and piping. PPS is also applied in oil field equipment such as lift and centrifugal pump components, oil patch drop balls, rod guides and scrapers. 

NonmetalHc centrifugal pumps utilize polymers for all components coming into contact with the pumping media. Even the steel (qv) shaft is sleeved with plastic to isolate the shaft from the fluid. Mechanical seals are reversed so that the metal face does not come into contact with the corrosive... 

Centrifugal pumps are made up of several components and are expected to cope in a multitude of environments, some quite hostile, fin understanding of houi they luorh, uihy they tuorh, luhy and houi they go turong and luhat to da about It can only come from a mix of theory and experience, hut the theory needs to be presented in a form which Is absorbable and Interesting if it is to he retained... 

The final element of the equipment description is the equipment boundary figure. A boundary figure is included with each data cell to define the components and limits of the equipment associated with that cell. For example, the data cell boundary figure (Data cell 3.3.7.2.1.1) in Figure 3.2 shows that the centrifugal pump, seal system, motor, motor control unit, lube oil system, coupling, and transmission are all components of the equipment in the data cell. The equipment boundary is inherently reflected in the taxonomy number. 

It is important to recognize that a centrifugal pump will operate only along its performance curve [10, 11]. External conditions will adjust themselves, or must be adjusted in order to obtain stable operation. Each pump operates within a system, and the conditions can be anticipated if each component part is properly examined. The system consists of the friction losses of the suction and the discharge piping plus the total static head from suction to final discharge point. Figure 3-51 represents a typical system head curve superimposed on the characteristic curve for a 10 by 8-inch pump with a 12-inch diameter impeller. 

For the designer, the use of a standardised component size allows for the easy integration of a piece of equipment into the rest of the plant. For example, if a standard range of centrifugal pumps is specified the pump dimensions will be known, and this facilitates the design of the foundations plates, pipe connections and the selection of the drive motors standard electric motors would be used. 

The reduction of downtime of the instrument (i.e., operations of pump components, injectors, and detectors) can be controlled to some degree if sample solutions are filtered and/or centrifuged the use of a 0.2- or 0.45-pm-pore-size filter is generally recommend for removal of particulates [15]. Filtration as a preventive maintenance tool for FfPLC analyses is well-documented in the ht-erature [16-18]. 

Meyerhofer (4) examines the problem of spinning a two component system which is composed of solids" and a volatile "solvent". He includes the effect of solvent evaporation and a viscosity which depends on solvent concentration. In this model, the film height decreases with time not only because of the centrifugal pumping, but also because of the evaporation from the surface. As the film is depleted in solvent, the viscosity increases and less fluid is lost because of pumping. Eventually a finite film thickness can be reached because all of the solvent evaporates, and the film consists of only an immobile solid phase. The present analysis is similar to Meyerhofer s. His treatment of the evaporation is corrected, as is his conclusion on the effect of spin speed (which apparently is due to numerical error on his part), and some of his assumptions in developing the equations are relaxed. 

Figure 5-12 shows the basic components of a single-stage, horizontally mounted centrifugal pump. Liquid is pushed into the suction eye as the liquid level in the feed tank is carefully adjusted... 

Centrifugal pumps contain components with distinct purposes. The impeller contains rotating vanes that impart a radial and rotary motion to the liquid. 

Cavitation in a centrifugal pump, which has a significant, negative effect on performance, is the most common failure mode. Cavitation not only degrades a pump s performance, but also greatly accelerates the wear rate of its internal components. 

Pumps are designed to handle gas-free liquids. If a centrifugal pump s suction supply contains any appreciable quantity of gas, the pump wiU cavitate. In the e imple of cavitation due to entrainment, the liquid is reasonably stable, unlike with the change of phase described in the preceding section. Nevertheless, the entrained gas has a negative effect on pump performance. While this form of cavitation does not seriously affect the pump s internal components, it severely restricts its output and efficiency. 

SeUgrem et al. (2000) conducted tests on sand as well as sand-clay mixtures pumped by centrifuged pumps. The phosphate clays had a diameter d Q between 1 p-m and 50 p,m. The sands were much coarser with of 0.64 mm (0.025 in), 1.27 mm (0.05 in), and 2.2 mm (0.09 in). The presence of clay and other particles finer than 75 p,m and a concentration smaller than 20% had a beneficial effect by reducing the head loss and efficiency derating factor. The data recorded by SeUgrem et al. (2000) should not be applied to a higher concentration of clays because the viscosity effect introduces a new component to the equation. 

As shown, a large generic data set of centrifugal pumps has been chosen to represent specific groups of components due to lack of more relevant data. 

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