What is the screw for on a double check valve?

Most outside taps have an integral double check valve, look for the small drain screw on the underside, that allows the space between the two check valve to be drained.

Is a double check valve the same as a backflow preventer?

A double check valve or double check assembly (DCA) is a backflow prevention device designed to protect water supplies from contamination. Secondly the closure of one valve reduces the pressure differential across the other, allowing a more reliable seal and avoiding even minor leakage.

Where should a backflow preventer check valve be installed?

Where is the Backflow Preventer Located? You should have your backflow prevention assembly installed inside an above-ground enclosure. It’s the safest and most cost-effective place to put it.

When should you use a double check valve?

A double check valve is used for fluid category 3 protection, where there is a risk of substances of low toxicity such as common disinfectants.

Why do you need a double check valve?

Double check valves protect the water supply from the risk of backflow and back siphonage in domestic homes and commercial buildings, ultimately preventing potential contaminants getting into other parts of the system, especially drinking water.

Can I use a check valve instead of a backflow preventer?

A backflow preventer protects your potable water. A check valve controls flow but it is not absolute. A check valve is not an appropriate substitute for a backflow preventer.

Can a double check valve be installed underground?

A more foolproof, convenient, and cost-effective option is to purchase a pre-assembled double check valve assembly. The Double Check Valve Assembly: May be installed either above ground or inline (underground)

Do you need a backflow preventer on sprinkler system?

Backflow preventers are required for all irrigation systems. Backflow preventers keep irrigation water from contaminating potable water and protect the public’s health, safety, and welfare. MORE ARTICLES ON IRRIGATION AND WATER IN CALIFORNIA: Potable water regulations.

Can backflow preventer installed vertically?

There are backflow preventers that can be installed horizontally, vertically (up or down) and other orientations that can make an installation easier. The key point to realize however is that they can only be installed in the orientation that the approval agency has determined they will work in.

Can a double check valve fail?

Double check valves are called so because there are two valves inside which act as a safety feature. It’s extremely unlikely that both valves will fail. If one valve fails, the other acts to prevent backflow and contamination in the mains water supply.

What’s the difference between backflow preventer and double check valve?

Double Check Valve backflow preventers are specifically designed to protect fire protection systems. Source: Watts A Reduced Pressure Zone (RPZ) backflow preventer ups the protection of redundant check valves even more.

Why do you need a double check valve assembly?

This double check valve assembly is designed to prevent the backflow of polluted water from entering into the potable water supply due to back siphon-age and or backpressure. It’s compact modular design means easy maintenance with a single access cover for in-line repairs.

How much does it cost to fix a backflow valve?

Backflow can also be extremely expensive to remediate: the Environmental Protection Agency (EPA) states that the average backflow incident takes nearly 500 hours to fix at a cost of $14,800. Like a check valve, a backflow preventer is a device that ensures water only travels in one direction.

What can cause a backflow valve to close?

Damage can also be caused by water hammer, in which flow reversal downstream causes the valve to abruptly close—resulting in a pressure wave that propagates throughout and damages the pipe. Improper maintenance, installation, or assembly can also lead to failures.