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 benefitting the system.
Large hydro tanks are designed to limit the number of pump cycles, not for water storage. A 10,000 gallon hydro tank only has about 1,200 gallons of useable water, the rest is air space. During a power outage this 1,200 gallons of useable water only gives a few minutes of water as pressure rapidly decreases to nothing. A water tower will deliver more water during a power outage but, depending on the rate of usage at the time, could still be out of water in a couple of hours. Real backup water supply means being able to utilize water from the main reservoir during a power outage. A backup generator or a diesel powered backup pump can continue to supply the system as long as there is water in the main reservoir. This can change the backup water supply from minutes or a couple of hours to several days, weeks, even months if need be. These backup pumps or generators can give an almost unlimited supply of water for a fraction of the price of a water tower.
The Cycle Stop Valve eliminates problems associated with ordinary pump control valves and variable speed drives. Pumps have a guaranteed minimum flow, run at a constant speed, powered by smooth AC power, without cycling. The system benefits from a constant and steady pressure eliminating devastating pressure surges and the need for expensive pressure tanks and water towers. The Cycle Stop Valve is completely mechanical, designed to hold a constant downstream pressure, and basically leak 5 GPM through when in its fully closed position. The simplicity of the Cycle Stop Valve eliminates the need for complicated and expensive controls. While electronic systems can be used for monitoring purposes, the less they have to do with actual operation of the system, the more dependable the supply of water. Pumps equipped with a Cycle Stop Valve can be controlled by systems such as SCADA. However, we have been told that one of the greatest benefits of the Cycle Stop Valve is that, when all the electronic systems have failed, pumps can be turned on manually to continue the supply of water, without harming the pump or system in anyway.
Different states and countries handle constant pressure systems differently. Some states, like Florida and Washington are trying to improve the quality and delivery of water to their people. These states have added constant pressure valves to their building codes or design manuals for municipal systems. Consumers in these states are enjoying a constant pressure supply of water, a decrease in cost and footprint of water supply systems, elimination of contamination and waste that goes along with water hammer, and a renewed respect for their state engineers. Other states have been slow to adopt constant pressure systems. These states are wasting taxpayer money on water towers, large pressure tanks, energy, and pump maintenance that could be better put to use on things like schools, roads, and the welfare of the people. Engineers should be educating themselves on new and beneficial innovations instead of sitting back in their comfort zone and continuing to use old technology.