Work Performed in Pumping

Work Performed in Pumping To cause liquid to flow, work must be expended. A pump may raise the liquid to a higher elevation, force it into a vessel at higher pressure, provide the head to overcome pipe friction, or perform any combination of these. Regardless of the service required of a pump, all energy imparted to the liquid in performing this sei vice must be accounted for consistent units for all quantities must be employed in arriving at the work or power performed. 

The term pump head represents the net work performed on the liquid by the pump. It is eomposed of four parts. They are the statie head (Hs), or elevation the pre.ssure head (Hp) or the pre.ssures to be overcome the friction head (Hf) and velocity head (Hf), which are frictions and other resistances in the piping system. These heads are discussed in Chapter 8. The head formula is the following ... 

While pumps do not directly create pressure, the system pressure created by the restrictions or work performed by the system has a direct affect on the volumetric output of the pump. As the system pressure increases, the volumetric output of the pump decreases. This drop in volumetric output is the result of an increase in the amount of leakage within the pump. This leakage is referred to as pump slippage or slip. A factor must be considered in all hydraulic pumps. 

The thermochemical determinations involving ions obtained via ES, described in this work, provide an illustration of opportunities presented by the ES method. However, these are only the beginning of what we believe should become an important area in gas-phase ion chemistry. The ion equilibria measurements, so far performed in our laboratory, were restricted by the limited upper temperature (T < 500 K). This restriction was due to the cryopumping used and could be easily overcome and the temperature extended upwards by -200 K by using conventional pumping. 

Hagman and Sivertsson discussed the work performed at Pharmacia and Upjohn52 on monitoring and controlling bioprocesses. They followed the protein production-derived form Chinese hamster cells (CHO-cells) in a 500-1 reactor over a 3-month period. The diagrams of the flow cell and pumping/NIR system are displayed, and the logic behind the work outlined. External and on-line calibrations were performed. 

Some of the modern surface analysis methods have been used to study the surface chemistry of both plasma etched surfaces and plasma polymerized thin films. Much of this work has involved exposure of these surfaces to air as the samples are transferred from the plasma system to the surface analysis system. However, in a few cases surface analysis has been performed in the plasma system after the plasma gas has been pumped away. This work will be discussed in more detail later in this chapter. 

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