What Is a Backflow Preventer Sprinkler System?

Housings and Fittings

• Most vacuum breakers are made out of brass and have three main external components. The main body is shaped like a bell and houses the internal pieces. Attached to the body are two ball valves. These valves control the flow of water through the breaker and can be shut off for maintenance or cleaning. Like the body, the ball valves are made out of brass. All three pieces are durable and resist corrosion.

Internal Components

• The inside of a vacuum breaker contains a pressure spring, poppet, bonnet and O-ring. These pieces work together to form a pressure seal within the breaker. When water is flowing, the pressure pushes the spring back and allows the water to flow in only one direction. If the water begins to flow backward, the spring releases and cuts off the flow of water. The poppet, bonnet and O-ring keep the system watertight. All of these components can be easily replaced if damaged.

Installation Requirements

• All vacuum breakers must be installed at the highest point along the sprinkler system in order for them to function properly. That's because air pressure works inside the breaker, and water that flows from above it will cause the breaker to fail. As a general rule of thumb, vacuum breakers should be installed at least 2 feet higher than the sprinkler manifold. The manifold is located within the irrigation control box.

Brands and Variety

• Most home improvement stores carry more than one brand of sprinkler vacuum breakers. The important thing to remember is that all brands of vacuum breakers work the same way. There may be cosmetic differences, and the replacement parts probably are not interchangeable. As of 2011, most of the leading brands of vacuum breakers had a retail price of about $90 each, depending on the size. Models are available in 3/4-inch or 1-inch configurations. The 1-inch models generally cost a little more. You must select the vacuum breaker that fits the size of your supply lines.