a set of devices that usually includes a pump unit, intake (suction) and discharge (pressure) pipelines, and reservoirs for liquid, as well as fittings (valves and so on), control devices, and checking and measuring instruments (including signals and automatic control devices).
Pumping plants may be permanent or for temporary or short-term duty. In the latter case movable pump units are frequently used, and flexible hoses are substituted for metal piping. Pumping plants may also be classified according to purpose as construction, water-supply, and sewage plants. Multiunit pumping plants may have individual, parallel, or series operation of pumps.
The most important technical characteristics of a pumping plant (see Figure 1) are the geometric suction height hg,s and the discharge height hg,d, the sum of which is the total pumping height hg; the pressures p1 and p2 on the liquid surfaces in the intake and pressure reservoirs, respectively; the diameters and lengths of the intake and discharge pipelines; and the ratings of the pump unit.
The operating conditions of a pumping plant are established as a result of the interaction of the pump unit with the other basic components of the plant. Under normal procedures pump pressure is always equal to the pressure against which the pump is working under given conditions (including hg, pressure losses hw in the pipelines, and the pressure difference p2 — p1). A change in the operating conditions of a pumping plant may be caused by various factors (such as an increase in p2, hw, or hg), or a change may be made intentionally, by a specific method of regulation (for example, by changing the speed of rotation of the pump shaft).
To achieve normal operation of a pumping plant, the height of the pump location above the level of the liquid being pumped must not exceed the permissible suction height. Automation of starting and stopping of the pump, breakdown prevention, and other processes associated with the operation of a pumping plant can be achieved by means of the appropriate relays (level, pressure, or thermal relays), contactors, and magnetic starters.
REFERENCES
Turk, V. I. Nasosy i nasosnye stantsii, 2nd ed. Moscow, 1961.Lobachev, P. V. Nasosy i nasosnye stantsii. Moscow, 1972.
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