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Old 02-27-2020, 12:26 PM   #10 (permalink)
redneck
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https://backflowtesterservice.com/wh...nter-required/


Quote:
What is “Backflow”?

Simply put, “backflow” means that water flows in the plumbing system have become reversed, causing potable water– clean water you can drink– to mix into the used water, which contains bacteria, chemicals, and other harmful contaminants.

Usually, water backflow results from one of two key processes: backpressure or backsiphonage.

Backpressure is a form of water backflow that results from an imbalance in water pressures. The downstream pressure is greater than upstream, or supply, pressure. Essentially, your home or building’s plumbing system contains water at greater pressures than the municipal water mains, which isn’t supposed to be the case. This pushes used wastewater from your plumbing system into the municipal water supply, potentially contaminating potable water. An example might be if you have a large water boiler that’s connected via plumbing with the potable water supply. Without a backflow prevention assembly, high pressure in the boiler could push dirty water into the clean water, contaminating it with sediment and other materials that could make it unsuitable for drinking.

Backsiphonage results from negative pressure, creating a partial vacuum effect. The systems distributing the water fall behind in the system using the water, in terms of water pressures. As a result, a siphoning effect moves contaminated water in the wrong direction. This can happen during a water main break, or in an emergency when a nearby fire hydrant is used (which involves high water pressures).
Quote:
Backflow preventers are commonly installed in buildings where clean water cross-connects with any of the following installations:

Large boilers. A large boiler can present a backflow hazard when the pressure inside gets too high, pushing the dirty water inside back up into the clean water system.

Irrigation systems. This includes extensive lawn sprinkler systems. Backflow from irrigation systems is hazardous because of the presence of fertilizers and lawn chemicals such as pesticides.

Fire suppression systems. Fire suppression systems can also create pressure differences and siphoning effects that can lead to backflow.
It’s pretty much the same in every state.


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