3.73 Water booster pump station
Water booster pump station
The function of the water booster pump station is to create the necessary increase in pressure for the distribution of water in the upper high zone of an urban district.
Method of operation
Normally the pumping will be automatically adjusted to water consumption in the upper high zone in such a way that the pressure in the outward delivery pipe is maintained more or less constant. Adjustment to the actual pressure is affected partly by means of change in speed of one of the electrically powered pumps, partly by changing the number of pumps in operation. Variable speed is obtained with the aid of an AC motor and frequency inverter.
Figure 3.73a Pump curve booster pump station
Valves
Every pump has a manually adjustable gate valve located in the connection to the common suction pipe. In the connection to the common delivery pipe every pump is provided with a manually adjustable gate valve and a non-return valve. The gate valves are dimensioned according to fit the station performance and normally pipe dimensions. A cold water meter, fitted with a mechanical recording device is installed in the suction pipe.
A pressure control connected to the delivery pipe measures the changes in pressure caused by variations of consumption and transmits signals to cause the necessary changes in speed and number of pumps so that the pressure is restored to the value set on the pressure control.
Normally the pumping station is operated without local supervision. This is performed from the remote station by monitoring the water pressure on the delivery side of the pumping station. In addition, signals are transmitted to the remote control station in the case of certain faults described in greater detail below.
Operating sequence
When water consumption is low, the speed-regulated Pump 1 (P1) operates alone. Speed is increased as consumption increases. When consumption surpasses the capacity of P1, either P2 or P3 is put into operation. Which of the pumps that comes into operation (P2 or P3) is decided with the aid of a switch, by timer or varies automatically though settings in the control system. With the intention of reducing variations in pressure experienced when starting a constant speed pump, the speed of pump P1 is reduced before another pump comes into operation. A similar procedure is followed when a constant speed pump is withdrawn from operation. At peak consumption all three pumps are in operation.
Limitations of operation
The pumping station is disconnected in case of insufficient pressure on the suction side or excessive pressure on the delivery side. Not until the pumping station has been inspected by staff is it possible to start up the pump again. The speed-regulated pump can only be started at minimum speed.
