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Boosting from One Pump Station to Another
Boosting water from one place to another can be easily controlled using Cycle Stop
Valves. Following are a few examples of how to pump in series using Cycle Stop
Valves.
#1
A rural water system as an example has 170 miles of pipelines and supplies only 140
connections scattered throughout this distance. Two water wells supply a total of
700 GPM to feed the system. The wells pump a short distance to a storage tank
then a duplex pump system draws from this storage and boost to 90 PSI. This
booster sends water about 10 miles to another storage tank and booster pump.
The second booster sends water another 10 miles to a third storage tank and
booster pump system. The process is repeated over and over fourteen times. All
along the 170 miles of pipelines there are houses randomly tapped into the line.
An old system used probes to control the level of the storage tanks. When a
storage tank was full, a signal would be sent 10 miles upstream to shut off the
booster pump. A low probe would send a signal to start the booster. Storage tanks
would continually drain and be refilled. A major problem occurs when the booster
pumps start or stop. No matter how slow you start the pump or open a control
valve, the pressure would spike. Trying to get a ten mile long line of water started
could not be done slowly enough to prevent pressure spikes and main line breaks.
Then when the storage tank was full, turning off the booster pump would cause a
dip in pressure that was followed by another water hammer. These pressure
spikes were causing 300 major line breaks each year. Not just a little leak but,
ripping out a forty foot section of 8" pipe and a roadway.
The Cycle Stop Valve solution was to keep the flow moving. Equipping all pumps
with a Cycle Stop Valve means that the usage in the system is continuously
matched. The inlet of each storage tanks was also equipped with a special low
pressure Cycle Stop Valve. The Cycle Stop Valves on the inlet of the storage tanks
close down to a minimum of 5 GPM and are set at 10 PSI. This keeps a constant
level of 23' in each storage tank as long as there is a demand for at least 5 GPM.
If the system accidently ever went to zero flow, the storage tanks would overflow
at the rate of 5 GPM but, the flow would continue to move. The wells now only
supply as much water as the entire system is using. Each booster pump now
supplies only the amount of flow being used downstream of that booster system.
The flow in the system never stops, as the flow rate used in the system is
continually matched by the Cycle Stop Valves. Flow rates in the system can vary
from as little as 5 GPM to as much as 700 GPM without ever stopping the flow in
any of the lines. Taps can be installed anywhere in the system from the discharge
of the Cycle Stop Valves on the well pumps to the furthest line past the last
booster pump. This continuous matching of the flow completely eliminates the line
breaks that occur from frequent starting and stopping of the pumps.
#2
The same system as above can be done without using the storage tanks. Each
booster system can draw water directly from the end of the ten mile water line
coming from the last booster or well. Simply pick up the water at 20 PSI and
boost it back up to 90 PSI sending it on down the next ten miles of pipeline. Each
booster system should be fitted with a low suction pressure cut off switch. If
there is not at least 10 PSI of pressure feeding the booster then that booster will
not be allowed to run. This means of control eliminates the need for the storage
tanks that normally feed each booster system. These tanks are not usually large
enough to be of any good for storage and are only used as a buffer between the
old type booster system controls. Eliminating these tanks will save on purchase
cost as well as energy. The pressure feeding each booster pump is the pressure
left over from the last ten miles of boosting. Depending on the usage between
boosters and the friction loss at least 10 PSI and possible 50 PSI could be left
over to feed the next booster pump. Boosting this water from 50 PSI to 90 PSI
instead of from atmospheric pressure to 90 PSI saves considerable energy on
pumping cost.
Note; Because these type systems run continuously, different size pumps are
needed at each booster system to make the system efficient. A small pump can
efficiently handle the small demands then a larger pump is only started when
needed.
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