PEX Tubing
In A Multipurpose NFPA 13D Fire Sprinkler System

As more municipalities adopt Section R314 of the International Residential Code (IRC), requiring the installation of a fire sprinkler system in new one and two-family dwellings built after January 1, 2011, contractors and home owners alike are looking at various reliable, safe yet affordable options.

Materials that are most commonly used for fire sprinkler systems are PVC, steel, copper and PEX.

While most commonly applied in potable water and heating applications, PEX piping, with its competitive pricing and straightforward installation, is becoming a growing trend in fire sprinkler system design. Additional advantages of PEX include its endurance of freezing temperatures, corrosion resistance, and the need for less fittings.

According to the National Fire Protection Association (NPFA), PEX pipes can be used in multipurpose fire protection system under NFPA 13D code (Standard for the Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes). A multipurpose system supplies potable water for domestic use as well as fire sprinkler water through the same supply line.

A multipurpose system carries significant benefits such as savings on materials and labor (common pipes are used for plumbing and fire sprinklers), no need to install check valves or backflow preventers and no maintenance or inspections are required.

Usually, a licensed plumber is able to install a multipurpose fire sprinkler system and plumbing system, eliminating the need to hire an additional contractor. It’s important to note that such setup ensures that the fire sprinkler system is always on and is working properly. Any malfunction or accidental shut off will be promptly noticed, as it will affect the whole plumbing system.

NFPA 13D fire sprinkler system operates under normal water pressure, without a fire department connection; enabling a fire truck pump connection would require piping that can withstand pressure levels that are beyond capabilities of PEX.

The installation process is very similar to that of the PEX plumbing system and requires a 3/4" pipe and a manifold. The sprinkler is connected to the adapter tee and is mounted to the ceiling.
Once the piping is installed and connected to the sprinkler adapter tee, the system can be tested and pressurized.

All piping installation must follow NFPA 13D as well as plumbing code requirements. Installing sprinklers in bathrooms, closets, attics, and garages is not required. Sprinklers are usually covered and are activated, as needed when heat reaches a certain temperature level.

Local codes and regulations should be assessed prior to installation, as multipurpose systems are not approved in all localities. PEX is not approved for use in stand-alone systems by NFPA 13D, even though some states do allow it.