Watts LFN45BM1-U 3/4 3/4 IN Lead Free Copper Silicon Water Pressure Reducing Valve, NPT Union x FPT, Adjust 25-75 psi, Max Work 400 psi

It is built for potable service. The body is a lead free copper silicon alloy and the valve is flagged lead free, which is what inspectors are looking for on domestic water in occupied buildings. Seat disc is EPDM and the trim is engineered composite.

The LFN45B has a built in thermal expansion bypass, so when heated water expands and pushes back against the valve, it can relieve back toward the supply instead of spiking pressure in the building. That is a different arrangement from a closed system with a check style regulator. Whether your jurisdiction still requires an expansion tank is a local code call, but the valve itself is the bypass type, not a hard closed one.

Up to 180 F, yes. That is the maximum operating temperature, and the low end is 33 F, so the valve must stay above freezing. A typical domestic hot water supply at 120 to 140 F is inside that window. Anything running hotter than 180 F, such as a boiler or high temperature process loop, needs a different valve.

A stainless steel strainer is integral to the valve. On well water or older galvanized service lines that is the part that keeps grit off the seat, and it is the first thing to pull and clean if the outlet pressure starts creeping. No separate inline strainer is required for the valve's own protection.

No gauge is supplied with the LFN45BM1-U. To set the reduced pressure you will need a gauge downstream, typically a hose bibb gauge on a laundry or exterior spigot, while you turn the adjusting screw. The valve leaves the factory at 50 psi, so if 50 works for the building you may not need to adjust it at all.

The U denotes the union end. The LFN45BM1-U is furnished union NPT on one side and female NPT on the other, which is what lets you break the valve out of the line at the union nut for strainer cleaning or a full replacement instead of sawing pipe. On a property with several of these installed, that union is the reason a swap is a fifteen minute job.

No. The LFN45B bottoms out at 25 psi on the adjustable range, so a setpoint under that is outside what this valve will hold. For low pressure applications below 25 psi you need a regulator whose published range starts lower. Above 25 and up to 75 psi it is the correct valve, and it will take up to 300 psi on the inlet.

The order identity is Watts LFN45BM1-U 3/4, series LFN45B, part number 9478. That combination gets you the 3/4 inch lead free body, union NPT by female NPT ends, integral stainless strainer, and the 25 to 75 psi adjustment range every time. Specify by that model string rather than by series alone, since the series covers other sizes and end configurations.

The body is a lead free copper silicon alloy rather than standard brass, which is the alloy Watts uses for dezincification resistance in potable service. There is no added corrosion resistant coating on the body, so the corrosion performance comes from the base alloy itself. Internally the sealing disc is EPDM, a standard elastomer for cold and hot potable water within the valve's 33 to 180 F range.