In this article we will discuss about:- 1. Location of Pumping Stations 2. Site Selection for the Pumps and Pumping Stations 3. Sizing of Pump Units and Stand by Capacity.
Location of Pumping Stations:
The location of the pumping station is very important and should be done carefully. If the water is drawn from the tube-well it is the usual practices to construct the pumping station just above the tube-well, will be safe as well as the length of the suction pipe will be minimum.
In case the steam is used for the operation of the pumps, the pumping stations should be so located that coal and coal ashes can be easily stored and can be easily transported. If the water from the tube-well is pumped to the overhead storage tanks, it is necessary to place the pumping station as near to the storage tank as possible.
If the capacity of the storage tank is large and the land is very costly, it is advisable to construct the pump house and the overhead tank one over each other. But if land is easily available, it is preferable to construct the pump house slightly away from storage tank in the same campus.
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When the water is drawn from the rivers, lakes or impounded reservoirs, the pump house should be directly constructed on the intake well. This will reduce the length of the suction pipe. If the water is supplied from the underground reservoirs located at the waterworks, the pump house should be located on one side of the reservoir from where it should pump the water in the mains. Such location of the pump house will eliminate the priming of the centrifugal pumps.
As pumps are the most important points of the water works, and in case of their breakdowns, the area will remain without water. Therefore, it is utmost necessary that the pumps should be reliable and should work for long periods without stoppage for cleaning, repairs, maintenances etc. Maximum quantity of water can be lifted with minimum consumption of fuel.
Site Selection for the Pumps and Pumping Stations:
Following points should be kept in view, while selecting the site for the pumps and pumping stations:
(i) The location of the pumps should be above H.F.L.
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(ii) Required quantity of water should be available as the site.
(iii) The pumping station should be at higher level above all the sources of contamination.
(iv) The location site should be such that future growth and expansion may be possible.
(v) The source of water should be permanent. In case of meandering rivers, the site should be such that the water is available at the pumping station.
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In case site selection is not done properly, there will be scarcity of water causing permanent trouble.
Fig. 6.13 shows typical layout of a pumping station and Fig. 6.14 shows the section through a typical pump-house.
Sizing of Pump Units and Stand by Capacity:
A water works pumping station is generally not operated at full capacity, all the times. Since the efficiency of a pumping unit varies with the load, it is a usual practice to so design such a station, that some of the pump units can be operated at full capacity all of the time. Hence, two, three or four pumps can be installed.
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Say for example, if there are four pumps the two largest may supply the maximum demand; one of these and the smallest may handle the normal demand, and the other pump may care for the minimum requirement.
Thus, there will always exist some standby capacity to take care of repairs, breakdowns. etc. Generally 100% stand by capacity against average demand, and 33y to 50% standby capacity against the peak demand is considered sufficient and may, therefore, be provided at the pumping stations.