Three CSVs on Three 200 HP Pumps, with 80 Gallon Pressure Tank. Water Tower was removed for service. System has better pressure, less cycling, and No Water Hammer with CSV than with Water Tower.
The old way of system control was to fill a water tower or pressure tank and shut off the pump. The system demand would then empty the tank and the pump would be restarted. This process is repeated over and over because system demand is usually much less flow than the pump produces. The tank is repeatedly filled at maximum pump flow and drained at the rate of demand. This cycling on and off of the pump system causes a multitude of problems. Everything from the generators at the power station to the plumbing in individual houses or irrigation systems is stressed from the cycling of the pump. End rush currents from pumps starting stresses electrical components in the power grid from the generator to the pump motor itself. Water hammer and surge from pumps starting and stopping stresses tanks, valves, and all piping in the distribution system. Long water lines between the pump and the pressure tank, water tower, or storage tank are especially vulnerable. Changing the flow in these long lines from a dead stop to full pump flow then back to a dead stop, can cause tremendous surges, or swings in pressure, that are responsible for numerous and expensive line breaks.
Cycle Stop Valves vary the pump output to exactly match the demand. A jockey and or a base load pump runs continuously and is throttled with a Cycle Stop Valve to exactly match the demand. When demand is greater than these small pumps can produce, larger pumps are brought on line as needed, and their output is throttled with a Cycle Stop Valve to continue matching the flow demanded. When flow demanded is reduced, larger pumps are turned off when no longer needed. The base load and or jockey pump will continue to run matching smaller flow rates as long as at least 5 GPM is being demanded. Continuous and instantaneous matching of the demand instead of completely starting and stopping the flow eliminates pressure surges in pipelines and reduces end rush required to frequently start pump motors. Continuous matching of the demand also reduces or eliminates the need for large pressure tanks and water towers, further benefiting the system.
