Backflow Basics: Fire Systems and Repair Tips

The author shares more information about backflow prevention devices to conclude this four-part series

Interested in Commercial Plumbing?

Get Commercial Plumbing articles, news and videos right in your inbox! Sign up now.

Commercial Plumbing + Get Alerts

In the final article of this four-part series about backflow prevention devices, I’ll look at fire systems, causes of failure and basic repairs.

Testing Fire System Backflow Devices

If you are getting into the business of testing backflows, you absolutely will test fire system backflow devices. There is nothing to be overly concerned about, but there are a few things to pay attention to.

These devices are usually large flanged double check devices that have alarm systems hooked up to them. If the water is shut off, the alarm sounds. Before you start shutting the water off on the fire system, fill out an invoice for the customer that says you are testing the backflow device and that you are “not financially responsible for any incidental/resulting fees or damages due to the required test.” Have them sign this before you begin because when you ask, “Does your fire system have an alarm if it’s shut off?” they likely won’t know the answer. If it has red plastic boxes and wires connected to the water system, more than likely it has an alarm. If you ask in advance and get your invoice signed, you’ll be covered no matter what. Technically speaking, you also need to tell customers to notify the fire department, their fire insurance company, and their alarm company.

Another thing to watch out for when testing fire system backflows are any fire-related people. If you see sprinkler fitters or a fire testing agency around the building you’ll be testing in, go talk to them and tell them what you are doing. The last thing you want is for them to be testing the building’s jockey pump system while you are shutting the building’s water off. The jockey pump maintains water volume and pressure using a very large pump that sucks as much water out of the main as required in case of a full-fledged fire. 

Common Causes of Failure and Repair Advice

There are two ways a backflow prevention device fails. The first is if one of the check valves has a worn rubber. The second is if the check valve has a nicked or pitted seat — same as any faucet or tub/shower valve. Keep in mind that if the device doesn’t hold, then it is not closing onto its seat all the way. It is your job to find out why. Most times debris that comes in at high velocities will wreck a check valve along with everyday buildup of corrosion. Water hammer will also cause havoc on the rubbers. You can take devices apart and have a look at the rubbers and the seats, just be careful when doing so. Utilize the test cocks and shutoff valves and verify that the water is truly off. I have seen situations where the test cocks are clogged shut. The technician thinks the valves are off and starts taking a check cap off. Then you have a problem.

You also need to keep in mind that there are two different types of valves in terms of how the protective caps come off. There are valves that are spring-loaded and ready to shoot out at your head, and valves where the springs are encapsulated by additional clips. They are called “captured springs” or “uncaptured springs.” Most times the devices with the missile caps are 2-inch brass or smaller and older.

Manufacturers don’t want you using any scouring agents to clean any of their seats or parts. No steel wool, emery cloth, or scotch pads. Only use soap, water, and clean rags. You will also need to grease the parts as they go back in. Use an approved plumber’s grease since it more than likely is going into a potable water system.

A Few More Notes

This series was written to give a basic overview of the backflow world. There is still a lot that I did not cover, such as the theory and science behind water and pressure. The point I’m making is this was an attempt to speak in simple terms from plumber to plumber. Sometimes teachers, professors, and instructors have a way of putting us to sleep with theory and what we consider to be meaningless numbers like the weight of a column of water. Sometimes it is better to just get down to it.

Do yourself a favor and get into an ASSE International or local certified backflow class and get it done for yourself and your career. There’s a ton of work out there with backflow prevention if you can pass. I’m not going to lie — the ASSE test compared to the early local tests is much more difficult. You must retake the entire course every three years to get recertified. There is an online test of a few hundred questions you need to pass as well as a hands-on test in which you have to test various types of backflow devices by complete memory. My advice: Get the test procedures and ask your boss for a few 3/4-inch backflow preventers of each type to practice on until you can do them with your eyes closed. Then enroll in the course and get after it.

If you missed any of the first three articles in this series, check them out here:

Why Should You and Your Customers Care About Backflow Prevention Devices?

An Overview of Different Backflow Prevention Devices

Testing and Installation

About the Author

Anthony Pacilla is a registered master plumber for McVehil Plumbing in Washington, Pennsylvania. He has 22 years' experience in the plumbing and HVAC trades, and has a bachelor’s in business and economics from Thiel College. 


Comments on this site are submitted by users and are not endorsed by nor do they reflect the views or opinions of COLE Publishing, Inc. Comments are moderated before being posted.