Fire sprinkler water sits in pipes for years. It’s stagnant, often discolored, and in some systems treated with antifreeze or other additives. A backflow assembly on the fire service keeps that water out of the public main. Seattle Public Utilities, for example, classifies standard fire systems as a low hazard protected by a double check–type assembly; systems with chemical additives typically call for reduced-pressure protection.
Detector assemblies, explained
Most commercial fire lines use a Double Check Detector Assembly (DCDA) or a Reduced Pressure Detector Assembly (RPDA). Each is a full-size assembly plus a small metered bypass. Low flows — a leak, or someone tapping the fire line for other uses — run through the bypass meter so the utility can see them. We test both the mainline and the bypass assembly.
Who can test a fire-line backflow
Washington requires inspection and testing of water-based fire sprinkler systems to be done by people certified by the State Fire Marshal — but the Washington State Patrol rules specifically exempt state-certified Backflow Assembly Testers while they inspect, test and maintain backflow assemblies. In other words, the backflow on your fire line is BAT work. Your annual fire sprinkler inspection (NFPA 25) is separate, and we’re happy to coordinate with your fire protection contractor.
How a fire-line test goes
- We call your alarm monitoring company to put the system on test.
- We close the assembly’s #2 shutoff — a supervised valve, which will trip a tamper signal — and run the field test.
- We restore every valve to its normal open position, confirm with the monitoring company that signals have cleared, and document it.
- The report goes to your water utility; a copy goes to you and, if you like, to your fire protection contractor.
A closed fire valve is a real hazard. We never leave a fire-line shutoff closed or unsupervised. If an assembly fails and can’t be repaired the same day, we restore it to service and tell you exactly what happens next.
