First used in water distribution systems in the 1970s, PEX — an acronym for crosslinked polyethylene — has quickly grown to be the most-installed piping product for potable plumbing systems in residential applications nationwide, more than copper and CPVC combined. It is even starting to take hold in commercial plumbing and hydronic heating and cooling applications, as well.

So, when it comes to piping a residential fire sprinkler system, it might be a smart idea to take a look at PEX to see what it can do to bring a stronger reputation and profitability your business.


Why PEX?

NFPA 13D-approved for use in multipurpose and standalone fire sprinkler systems, PEX has been shown to be an effective alternative to CPVC and copper pipe due to its easy installation and durability. Both characteristics allow contractors and builders to meet tight production schedules.

PEX won’t pit, scale or corrode like copper piping systems can in harsh water conditions. Its unique molecular structure is stable, inert and unaffected by chemicals commonly found in plumbing (as well as HVAC) systems. CPVC, however, is susceptible to environmental stress-cracking when in contact with common construction materials, such as leak detectors, thread sealants, pipe wraps, lubricants and caulks.

PEX is also very flexible. For example, ½-inch pipe can offer a bend radius as little as 3.5 inches. This is important for two reasons.

First, since the flexible pipe is available in long coil lengths, an installer can simply bend the pipe to make a change in direction without having to stop and cut in a fitting. This saves time, reduces materials costs, and limits potential leak points in the system.

Second, because flexible PEX can expand up to three times the pipe’s diameter, it is highly resistant to freeze damage. It can expand to accommodate frozen water in the pipeline and then contract back down to its original shape once the water thaws.

For example, a six-month-old home in Washington state lost power a few years back and went without heat for four days. This caused the water inside the CPVC piping to freeze and the pipe to crack. The PEX system in the house, however, suffered no stress fractures.

This shape-memory property also allows accidental kinks in PEX pipe to be repaired with a controlled heat source such as a heat gun. As it cools, the pipe will always return to its original shape and size, meeting the same standards and possessing the same qualities as before. The ability to remove kinks quickly and easily is especially valuable during installation, as it minimizes the time and cost of pipeline repairs.


The connection is key

Another benefit of PEX is the connection method. Because of its shape memory that ensures the pipe will always return to its original shape after being expanded, the pipe works very well with cold-expansion fittings. These fittings use the shape memory of PEX to create strong connections that hold tight with 1,500 pounds of radial force.

To make a fitting, the installer simply places an expansion ring on the end of the pipe and then expands the pipe and ring with an expansion tool. Once expanded, the installer inserts a larger-diameter fitting. As the pipe and ring shrinks back down to its original shape, it creates a strong, leak-resistant connection.

Best of all, because the pipe must be expanded before inserting the fitting, it eliminates dry-fit issues. For installers who have ever missed cementing or soldering a dry-fitted connection, this is a game-changer.


Learn more

If this article has piqued your interest on the benefits of PEX and you want to learn more, check out or These are two of the industry’s most valuable websites for general information about PEX piping systems.

If you’ve read and heard all you need to know and you’re ready to add PEX to your repertoire, there are manufacturers that provide regional and jobsite training for licensed contractors. It’s fast and easy to learn and offers many benefits for installation efficiencies and cost savings.