February 17, 2014

Metropolitan System Protects the City Water Supply

This air-gap/ break tank system, for supplying non-potable water, was recently shipped to a Wastewater Treatment Facility in Washington.

This air-gap/ break tank system, for supplying non-potable water, was recently shipped to a Wastewater Treatment Facility in Washington.

Cross connections between city water supply and water piping in certain types of public and private facilities constitute a potential public health risk. Owners of properties that pose an actual or potential risk of contamination are required to install some means of cross-connection control on the main water pipes that supply their buildings. A device is needed to prevent potentially contaminated water from flowing back into the city’s water supply. Typical approved devices include reduced pressure zone device (RPZ), double check valve (DCV, DCVA), or a physical air gap. The use of RPZs requires a significant amount of regular maintenance to insure the water source is protected.

While RPZs and DCVs have been approved for years, many governing agencies are making the transition to an air gap/ break tank system. The use of an approved air gap system requires an isolated storage tank and a separate booster pump system to re-pressurize the water supply to the facility and it provides a more positive means of separation and protection of the public water system in the event of contamination within the customer’s facility.

Metropolitan Industries recently provided an air-gap/ break tank system, for the supplying non-potable water, at a Wastewater Treatment Facility located in Washington.

After years of using a RPZ backflow prevention device, the plant decided to replace the device with a more reliable prevention system, to completely eliminate the risk of contamination. The air gap creates a barrier to backflow so there is a zero percent chance the water will become cross-contaminated.

“More and more communities are beginning to look past RPZs and towards the air-gap/ break tank system,” said Metropolitan Industries National Sales Manager, Mike Tierney, “Metropolitan is one of the companies at the forefront of this technology.”

For this application, Metropolitan designed a triplex, pressure booster system with air gap protection for the non-potable water supply and a 540 gallon tank with a system capacity rated for 290 gallons per minute.

Variable frequency drives are often used on the air-gap water pressure booster. The VFDs accurately control the speed of the pump motor to maintain a constant pressure in the facilities water piping. VFDs also minimize the electrical power used to re-pressurize the water, saving the owner money on their utility bills.

Sewage treatment plants, laboratories, boiler plants, warehouses, manufacturing and processing plants are just a few of the types of facilities that can make use of an air gap pressure booster system as a positive means of cross-connection control. The packaged air-gap/ break tank system is typically supplied complete with tanks, pumps, motors, piping, valves and controls all factory assembled and tested.

With the liability of protecting a city’s water supply, there is a real need for a reliable system that is a fail-safe solution to protect the water.

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