"Few engineered artifacts are as essential as pumps in the development of the culture which our Western civilization enjoys" (Garay, 1990). This statement is germane to any discussion about pumps simply because humans have always needed to move water from one place to another against the forces of nature. As the need for potable water increases, the need to pump the water from distant locations to where it is most needed is also increasing.

Initially, humans relied on one of the primary forces of nature— gravity—to move water from one place to another. Gravity only works, of course, if the water is moved downhill on a sloping grade. It was soon discovered that the pressure built up by accumulating water behind the water source (e.g., behind a barricade, levy, or dam) moved the water farther. But, when pressure is dissipated by various losses (e.g., friction loss) or when water in low-lying areas must be moved to higher areas, the energy required to move that water must be created. Simply, some type of pump is needed.

In 287 B.C., Archimedes, a Greek mathematician and physicist, invented the screw pump (see Figure 10.1). It is believed that around 100 A.D. the Roman emperor Nero developed the piston pump. The piston pump displaces volume after volume of water with each stroke. The piston pump has two basic problems: (1) its size limits capacity and (2) it is a high energy consumer. It was not until the 19th century that pumping technology took a leap forward from its rudimentary beginnings. The



first fully functional centrifugal pumps were developed in the 1800s. Centrifugal pumps can move great quantities of water with much smaller units compared to earlier versions of pumps.

The pump is a type of hydraulic machine. Pumps convert mechanical energy into fluid energy. Whether water is being taken from groundwater or a surface water body, from one unit treatment process to another, or to a storage tank for eventual final delivery through various sizes and types of pipes to the customer, pumps are the usual source of energy necessary for the conveyance of water. Again, the only exception may be, of course, where the source of energy is supplied entirely by gravity. Waterworks and wastewater maintenance operators must therefore be familiar with pumps, pump characteristics, pump operation, and maintenance.

There are three general requirements of pump and motor combinations. These requirements are (1) reliability, (2) adequacy, and (3) economy. Reliability is generally obtained by installing in duplicate the very best equipment available and by the use of an auxiliary power source. Adequacy is obtained by securing liberal sizes of pumping equipment. Economics can be achieved by taking into account the life and depreciation, first cost, standby charges, interest and operating costs.

Texas Utilities Association (1988)

Over the past several years, it has become more evident that many waterworks and wastewater facilities have been unable to meet their optimum supply or treatment requirements for one of three reasons:

1. Untrained operations and maintenance staff

2. Poor plant maintenance

3. Improper plant design

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