Backflow Preventer Valve - Some Facts You Need To Know

By | November 11, 2016

With lots of backflow preventer valve currently available in the market, it is understandable that one be easily confused in choosing the right equipment to buy. This article should help you address this confusion and help you decide which water backflow preventer to purchase and install.

For starters, we shall be discussing the most commonly used backflow preventer valve. If you are intending to install such type of a device in your home, this article should help you get familiar with the understandably confusing names of each equipment.

Aside from the Reduced Pressure Zone (or Reduced Pressure Principle Assembly) and Pressure Vacuum Breakers (PVB), there are other types of backflow preventer valve that are used for particular purposes. The ones in this list are commonly used in both residential and industrial water systems.

The Double-Check Valve backflow preventer

Double check valves (DCV, also called double check assemblies or DCA) are typically the go-to device for underground or indoor installations. DCV’s consist of an inlet shutoff valve, two independently operating spring-loaded check valves (usually inside a single valve body), four test cocks, and an outlet shutoff valve.

DCV’s allow for the flow of pure water that is not open to contaminants in the air. They also cost a lot cheaper compared to other types and are usually installed beneath the ground and/or in basements to protect them from freezing.

One disadvantage of the DCV is that although the equipment is built with two check valves, in the event that or other particles make their way to one valve, it is highly like that the other valve may also fail at the same time.

The Dual-Check Valve

A Dual-check valve is a type of a water check valve backflow preventer that is typically used by water companies and installed after a water meter to prevent the meter from running backwards.

Fair warning: the Dual-Check Valve should never be confused with the Double-Check Valve as the former is a stripped down version of the DCV minus the shutoff valves and test cocks. Also, Dual-Check Valves have stirred some controversy in the backflow preventer valve industry as most authorities do not recognize them as backflow preventers.

Before installing a Dual-Check Valve, have the required testing done by a licensed plumber and make sure to perform necessary maintenance measures every a couple of years.

Atmospheric Vacuum Breaker

The Atmospheric Vacuum Breaker is one of the least expensive backflow preventer valve out there. Being also the simplest in terms of assembly and design, AVB’s are commonly used for one or two-zone irrigation systems.

In terms of reliability, the AVB has been known to be perform poorly compared to other backflow preventer types. This particular type does not actually prevent backflow pressure and only protect against back siphonage.

Experts in the industry do also not advise the installation of AVB’s as they were not designed to withstand constant water pressure, making them not cost-effective at all. In fact, most cities do not allow for the installation of the AVB for residential lawn sprinkler systems.