Protecting Double-Check Valve Assemblies and RPZs

When it comes to protecting your backflow assembly, there’s a right way and a wrong way. Choosing the right way means offering the most complete protection you can provide your water supply and your employees. Installing your backflow prevention assembly improperly exposes it to unnecessary flooding risks. Here’s why:

Double-Check Valve Assembly

A double-check valve assembly is working properly anytime the pressure on the property side exceeds the pressure on the city side and the two redundant check valves close. This prevents backward water flow.

But because it is a closed system, there are two problems with the double-check backflow preventer:

  • It has no method of revealing whether the internal check valves are functioning properly.
  • There’s no way to detect the presence of debris that is impeding full closure of the checks.

That’s why double-check (DC) valve assemblies in many jurisdictions are acceptable for low-hazard conditions only. But is this really an acceptable situation?

Typically, the water purveyor determines what constitutes low-hazard conditions. But what complicates the decision is the differences between every jurisdiction.

Doublecheck Valve Assembly


RPZ Valve Assembly

Reduced Pressure Zone (RPZ) valve assemblies, on the other hand, provide the highest level of protection for your water supply.

There is one critical difference between an RPZ and a DC: RPZs are designed to dump water to protect the water system.

An RPZ uses two independently operating check valves, just like the DC valve assembly. But it’s also equipped with a hydraulically-operated differential relief valve that’s located below the first check valve.

This hydraulic valve (and its strategic placement) makes the RPZ virtually fail-safe because when the zone of pressure is compromised, the relief valve opens, and the water is expelled. Since it is virtually impossible for contaminants to backflow through an RPZ valve, they are trusted for maximum protection of the water supply.

RPZ Enclosures Protect Your Investment

Since RPZ valve covers provide the best barrier between backflow and your water supply, it deserves the highest level of protection you can provide. When it’s working properly, it floods the surrounding area, so an RPZ is better off in an enclosure outside the building.

In fact, RPZs offer so much peace of mind, many jurisdictions are now requiring their use on all domestic and fire service lines. And when it comes to installing RPZs, you essentially have two options: inside in a mechanical room (which exposes you to unnecessary flooding risks), or in an RPZ enclosure.

If you are an architect or design engineer, you’ll want your project to benefit from your good decision making. So don’t take the risk of installing the RPZ inside the building. Moving the RPZ outside and protecting it with an above-ground RPZ enclosure is your best option.

Get started by talking to one of our experts. They’ll take your exact measurements and put together a Reduced Pressure Zone Assembly or Double-Check Backflow Assembly enclosure that’s perfect for you.




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