According to a recent article from Global Market Insights, the fire sprinkler market was valued at $11.5 billion in 2023 with an expectation of an annual growth rate of 8.6% from 2024 through 2032. What is driving this extraordinary market size and growth? Governmental policies have mandated the installation of fire sprinklers in new commercial and residential buildings because there is a widespread acknowledgement that this method of fire suppression is the safest and most effective way to stop fires at their earliest stage, which saves lives and infrastructure.
As I mentioned in my last column, I cut my teeth in our industry designing backflow preventers. I learned early on of their health and safety benefits, and how they ensure water flows only in its intended direction. Backflow preventers are especially important in fire sprinkler systems, because the isolated water contained in them is hopefully infrequently used. As many a fitter will attest from their experience pulling a fire sprinkler from an older system, the stagnant water within the pipes is often foul smelling and discolored. Chemical and microbially induced corrosion are the chief culprits that cause this rank, stained and sometimes viscous water. Additionally, wet pipe fire sprinkler piping that is exposed to freezing temperatures is usually protected with an antifreeze solution. Obviously, this is water nobody would want to drink.
From the beginning, fire protection and backflow professionals have shared an alliance. Fire suppression system designers must consider pressure and overall flow requirements when sizing the system to ensure full flow at the most remote sprinkler head from the water supply.
Anything that robs pressure (like a backflow preventer) can be a cause of concern. Backflow professionals’ focus is on proactively protecting the potable water supply. Given these constructs, I have been pleasantly surprised to see these two groups work together to deliver fire sprinkler systems that meet the goals of each.
There are a few exceptions concerning when backflow protection is required on fire sprinkler systems. For residential applications, many installations today are the flow-through type that do not allow water to stagnate, so no backflow preventer is required. Dry standpipe systems also require no protection because they are not connected to potable water when not in use.
Section 603.5.14 of the 2024 Uniform Plumbing Code (UPC®) states: Except as provided in Section 603.5.14.1 and Section 603.5.14.2, potable water supplies to fire protection systems that are normally under pressure, including but not limited to standpipes and automatic sprinkler systems, except in one- or two-family or townhouse residential sprinkler systems, piped in materials approved for potable water distribution systems shall be protected from backpressure and backsiphonage by one of the following testable devices:
- Double check valve backflow prevention assembly (DC)
- Double check detector fire protection backflow prevention assembly (DCDA)
- Reduced pressure principle backflow prevention assembly (RP)
- Reduced pressure detector fire protection backflow prevention assembly (RPDA)
Based on my experience fielding calls from building owners, water consumers and inspectors, the two most misunderstood types of backflow preventers are the detector assemblies, DCDAs and RPDAs. What are they exactly? Simply put, they are enhanced versions of their namesake double check or reduced pressure principle backflow preventers. The detector assemblies have a bypass line that contains smaller versions of the mainline assemblies. Additionally, the bypass line contains a water meter and/or alarm signaling device. Since fire lines typically are not metered, unauthorized water use or leakage is detected in the bypass line, which accepts the first flow of up to 2 gpm (0.13 l/s).
Whether to specify a DCDA or RPDA on a fire service line depends on the degree of hazard. The two section exceptions noted in the UPC above make the distinction for us — fire department connections or when antifreeze, corrosion inhibitors, or other chemicals are added to a fire protection system creates a high hazard and necessitates the use of an RPDA. If a fire protection system contains only aesthetically unpleasant stagnant water with no chemicals added, no health hazard is present and a DCDA may be used.
Most inquiries I have received over the years were in regard to the Type II version of each assembly. In Type II detector assemblies, the mainline’s first check valve is used for both the mainline and the bypass, affording the same protection as a traditional detector assembly, but with fewer components and thereby producing an assembly with a more compact footprint.
Given the title of my column, I suppose now would be a good time to cite the relevant standards: Both ASSE 1047, Performance Requirements for Reduced Pressure Detector Backflow Prevention Assemblies, and ASSE 1048, Performance Requirements for Double Check Backflow Prevention Assemblies, were first published in 1990. ASSE 1047 and ASSE 1048 include 21 and 15 functional tests, respectively. Each also includes an optional one-year field test for those jurisdictions that require it.
