Watts F111604 4 IN SS Reduced Pressure Zone Assembly Backflow Preventer, NRS Shutoff Valves, Backflow Flood Sensor

An RPZ is the right choice for high hazard. The F111604 is rated for health hazard protection and guards against both backpressure and backsiphonage, which is what a double check assembly cannot do. It is also rated for continuous pressure operation, so it can sit under constant line pressure on a fire line, irrigation main, boiler feed or process connection.

It ships with non rising stem gate valves on both the inlet and outlet. NRS valves keep the stem inside the bonnet, so the handwheel does not travel upward when you open or close it and you need less vertical clearance than an OS&Y assembly. Worth noting if your fire marshal or local water authority specifically requires OS&Y valves for visual position indication, this unit will not meet that.

No. The working range tops out at 140 F (60 C) with a minimum of 33 F (0.5 C), so it is a domestic cold water and fire line device. Anything above 140 F needs a hot water rated assembly. The 33 F minimum also means it has to be kept from freezing, so plan on a heated enclosure or an indoor location in cold climates.

Not where a UL listed or UL classified device is specified. The F111604 carries no UL code rating and is not UL classified for the US or Canada. For fire protection service under a UL requirement you need a UL listed fire service RPZ instead. For domestic, irrigation and process high hazard isolation it is fine.

175 psi (12.1 bar). That covers standard municipal supply and most fire service pressures. If your static pressure runs higher than that, a pressure reducing valve ahead of the assembly is required.

Yes, it is a testable assembly, which is what most jurisdictions require for an annual backflow test by a certified tester. As a reduced pressure zone assembly it has the test cocks needed to verify the two checks and the relief valve.

The F111604 uses a stainless steel body and stainless finish rather than a coated cast body, which is the usual pick for aggressive or chloraminated water, coastal installations and outdoor vaults where a coating can chip and corrode. Internals are a silicone disc on an engineered plastic seat. There is no polymer coating on this unit because the body material itself is the corrosion barrier.

F111604, in the Watts 957-FS series. It is the 4 inch stainless reduced pressure zone assembly with non rising stem shutoffs and the backflow flood sensor. The FS suffix on the series is the flood sensor configuration, which is what distributors should reference when matching a spec calling for a sensor equipped 957.