Never Put Your Backflow Preventer Installation In The Basement

Part 2 of a 3-part series

Certain backflow preventer installations should never be installed indoors. The flange-size reduced pressure zone backflow preventers, those assemblies with a pipe size of 2½” and larger, is one of them. The risk of personal and/or property damage is simply too great because a flood will happen, even with conventional drain systems in the mechanical room floor.

In our last blog we discussed the various backflow preventer assembly failure scenarios and which failure combination represents the perfect storm, that single highest damage risk.  Today we’re discussing the flood itself.

A few years ago, Safe-T-Cover sent me on a mission to witness a failing RPZ backflow preventer. But as you might expect, such an event is difficult to capture live.  All it does is react. It has no idea – or opinion about – what will happen to the surroundings after the fact. It simply reacts.  

So without a way to predict when an RPZ will be forced into its reactive mode, I did what any normal person would do: I called the fire department. I told them what I wanted to see and they said they would like to see it too. Delighted at the idea of creating a bonafide catastrophe, we decided to create the event ourselves at the Nashville Fire Department Training Facility.

In setting up this failure, we removed the closing mechanism of the #1 check valve simulating a mechanical failure to close. Next, we jammed a small piece of solder debris into the hinge area of the relief valve where it is likely to get caught, and finally, we shut off the flow beyond the #2 check valve simulating a stop in user demand.

The fire department fed the assembly a flow of water at 88 PSI, a flow rate that would be consistent with overnight flow rates in well-served cities. While we were happy with the simulation, there are a few under-reported aspects of the test that should be kept in perspective. First, this is only a 3” reduced pressure zone backflow assembly. It is important to think about how much more damage a full grown – 8” or 10” – backflow assembly would do. It’s a difference in orders of magnitude rather than degrees. 

Secondly, the flow rate reached only about half of what the manufacturer specified was “possible.” This is precisely because of the mere 88 pounds of flow rate. If this assembly was in the basement of a high rise, and the failure had been the #2 check valve, the initial head pressure would have caused the flow rate to be much higher. On the other hand, without a constant flow from the public side, the head pressure would fall reasonably quickly and water release would eventually cease. Therefore, such an event, a failure of the #2 check valve, is not considered the worst case in terms of property damage. It is still clearly a large head volume from a large building which could be devastating and should not be underestimated.

 

 

 

In Part 3 of our series, we'll find out what's considered the safest place to install a backflow preventer. For more information, you can watch our webinar on best practices, or check out our guide “Trends in Backflow Preventer Installation.” It can show you some of the more common installation locations and the risks you take when you install a backflow preventer in a basement or a vault. 

Watch the 30 minute backflow installation and best practices webinar here

Best Practices in Backflow Prevention & Protection

 

Related Posts

DC vs. RPZ: What's the Difference?

Why RPZ Valves Are Required and How To Install One

What Are the Size Limits for a Custom Enclosure?

Winterize Your Backflow In Eight Steps (or One)

Aluminum Enclosures and Concrete Pads: Total Security and Confidence

One Step Ahead: A Look at High-Hazard Cross-Connections and Compliance

IoT Takes Backflow Prevention To Another Level

Protection from Sound and Fury: Safe-T-Cover Enclosures and Noise Dampening

From the Field - The Safe-T-Cover Advantage with a Damaged Enclosure

Think Outside the Vault: Fayetteville, North Carolina

From The Field: 2022 WASDA Fall Conference Recap

Fire Pump Housing Options Beyond the Building

Heading into the unknown: Another Big Freeze could be catastrophic

3 Reasons Why a Backflow Cover Must Have Heat

Water 2050: Preserving the Future of Water

From the Field: Tips for Safe-T-Cover Enclosures and Protective PVC Coating

From the Field – National Backflow Prevention Day

Forward thinking in Arlington, Texas: Leading the way with public health and backflow preventers

Texas Water Show 2022 Recap

Game changer: The Ames Deringer backflow

2021 YEAR IN REVIEW — FROM BACKFLOW BEST PRACTICES TO THE NEW INFRASTRUCTURE BILL

How a Project in Georgia Could Change the Face of the Backflow Protection and Enclosure Requirements

What Happens When a RPZ Fails?

Introducing Our New Best Practices Guide

Do Backflow Events Really Endanger Our Drinking Water?

The State Flower of Florida (Backflow Preventer)

Comparing the Costs: Meter Vault vs. Enclosure

Meter Vault Innovation — Check Out This Trend

The Drawbacks to Using a Backflow Valve Cage

Quintessential List of Backflow Preventer Enclosure FAILS

Chicago Backflow Incident of 1933

Three Reasons Why You Should Choose an N-Type Device

The Right Insulated Cover for Backflow Valve and Enclosure Heating

How Do You Hide A Backflow Enclosure?

How Does a Backflow Preventer Work?

What You Need To Know About Backflow Prevention Devices

This is How You Cut Backflow Preventer Installation Costs

This is How A Backflow Preventer Installation Should Be Done

Part 3: Why You Should Keep Backflow Preventers Out of Basements

Above-Ground-Backflow Assemblies Are a Big Winner in Las Vegas

A Backflow Preventer in a Utility Vault Can Be Deadly

How to Find the Perfect Enclosure for Backflow Prevention

How to Decide If You Should Repair or Replace Your Backflow Preventer

VIDEO: Safe-T-Cover Hopes To Change The Way You Think About Backflow

Expert Says Containment Protection is Necessary For Backflow Prevention

What You Need to Know About Backflow Prevention and Flood Risks

How To Build a Successful Cross Connection Control Program

What is a Cross Connection Control and Backflow Preventer?

Expert Says Backflow Prevention Can't Be Ignored Anymore

CONTAINMENT VS ISOLATION: THE COMMERCIAL BACKFLOW PREVENTER INSTALLATION BATTLE

How to design & Buy a Pump Enclosure

Get the free, editable checklist.

download-cta
DOWNLOAD NOW

CONTACT US

Have a question about a backflow preventer enclosure?
Click the contact us button below and one of our experts will be able to help with your specific enclosure needs.