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Types of Multipurpose Home Fire Sprinkler Systems
The following are 3 brands of CPVC piping listed for fire sprinkler system use and available in Maine. Their websites are listed as a resource for more information on their product with their installation specifications. These types of piping systems are also listed to be used in NFPA 13 systems as well as NFPA 13R & NFPA 13D systems when installed according to their listing.
Our office recognizes the following fire sprinkler systems for the National Fire Protection Association's (NFPA) 13D fire sprinkler standard, which is the fire sprinkler standard used primarily for private homes, (whether or not it is a single or duplex unit), and manufactured housing.
These systems have the added advantage that if the fire sprinkler system is shut down, then so also is the domestic water supply, thereby insuring that the fire sprinkler system receives prompt attention during maintenance.
As home fire sprinkler systems become more commonly required in codes and town ordinances, we look for ways to encourage their use. One way is to look for ways to make them more affordable, (which was the driving philosophy behind the creation of NFPA 13D), and this was so that we could get them into homes, which is where most of the fire deaths occur. As technology both improves and proves reliable, we accept new materials and methods to help with the affordability.
In this context, we now allow pex pipe in NFPA 13D systems not only when the fire sprinkler system is tied into the domestic plumbing, but also when it is not, (a “stand-alone” system).
The following restrictions apply for using Pex pipe in stand-alone fire sprinkler systems:
1. Must be NFPA 13D standard
2. Must not have a fire department connection
3. Must be “pex-a” grade of pex pipe unless the pex pipe is part of a system listed for fire sprinkler use and the pex pipe is installed according to the manufacturer’s specifications for that listed system.
We are doing this under the equivalency clause of NFPA 13D, 2007, section 1.4., “Nothing in this standard is intended to restrict new technologies or alternative arrangements, provided that the level of safety prescribed by the standard is not reduced.” We have restricted the type of pex pipe to be used, and we have restricted when it can be used independent of the plumbing.
There are 3 basic grades of pex pipe. They are a reflection of how the cross-linking of the molecules is produced. Pex-a pipe is produced under pressure/temperature. Pex-b is produced by saline/chemical bath. Pex-c is produced by light/radiation bombardment. The method that produces the most thorough and strongest cross-linking of the molecules is the pex-a method. “Pex-a” is stamped on the pex pipe, which makes it easy to verify which type it is. Pex-a pipe is readily available in Maine. The other two types are not although pex-b is available with a listed crimping system by Viega.
The 2007 edition of NFPA 13D allows pipe that has a 175 psi listing. Pex pipe is listed at 160 psi, so is just short of this listing. NFPA 13D however allows pipe of 130 psi listing to be used when the fire sprinkler system is tied into the domestic plumbing, which is how pex has been used and which is why it has been tied into the plumbing. Many states however have been allowing pex for stand-alone systems for some time because time has proven the pex pipe to be reliable for fire sprinkler systems. In other words, the integrity of the fire sprinkler system pex piping is the same whether or not it is tied into a toilet. The key issue is that pex pipe may not hold up well to the pressures applied by the fire department pumper trucks, but fire department connections are not required by NFPA 13D, so that would only be an issue when local authorities require there to be a fire department connection.
Some advantages that pex has proven worthy of are:
Our office is aware of 4 major manufacturers of pex pipe, so I am not favoring one company over another. This email is also not to be misconstrued as favoring one product over another, since there are other types of pipe such as steel, copper and CPVC that have other advantages over pex in certain situations for fire sprinkler systems.
The 2009 edition of the International Residential Code, (IRC), states in section R313.2.1 that “Automatic residential fire sprinkler systems shall be designed and installed in accordance with section P2904 or NFPA 13D.” Section P2904.3.1 states that, “Non-metallic pipe and tubing such as CPVC and pex shall be listed for use in residential fire sprinkler systems.” Some jurisdictions that have adopted this code interpret this as pex being acceptable for fire sprinkler systems independent of the plumbing, and so does Maine. Maine has adopted a state-wide building code called the Maine Uniform Building and Energy Code, (MUBEC), which includes the 2009 IRC, so our pex policy is also in harmony with the current building code.
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