Watts 0009478 3/4 IN Lead Free Water Pressure Reducing Valve, NPT Union x FPT, Adjust 25-75 psi, Max Work 400 psi

Yes. The LFN45B is a 3/4 inch valve with a 3/4 inch NPT union joint on the inlet and a 3/4 inch NPT female threaded outlet. The union inlet is the part worth planning for: it lets you break the valve out of the line for service without cutting pipe, but the outlet is a fixed female thread, so that side gets made up solid. If your line is copper, you need a male adapter on each side.

Yes, the LFN45B includes a thermal expansion bypass. That matters on any closed system: once you install a PRV the house is closed to the street, and a water heater firing will build pressure with nowhere to go. The bypass lets that expansion pressure back out through the valve toward the street rather than lifting the T and P relief on the heater.

The body is a lead free cast copper silicon alloy, which is what makes it suitable for potable water service. Internals are an elastomer disc with a stainless steel strainer screen. The lead free designation is why the model carries the LF prefix on the LFN45B series.

No gauge is supplied with the 0009478. You set it with a separate gauge, typically a hose bib gauge downstream or a gauge teed into the line after the valve. If you want the gauge integral to the regulator, order a gauge-equipped model instead of this one.

Maximum working pressure is 400 psi (27.6 bar), so incoming municipal pressure is not a concern for the valve body. The limit that actually decides the job is the outlet side: you can only reduce down to a setpoint between 25 and 75 psi.

A stainless steel strainer is built into the valve, so you do not need to pipe a separate strainer ahead of it. Leave clearance at the valve to pull and clean that screen. Debris in the strainer is the usual reason a PRV starts creeping or loses downstream pressure.

Rated to 180 F (82 C) maximum, with a minimum of 33 F (0.5 C), so it handles domestic hot water as well as cold supply. The low end is a reminder that it is not freeze rated: keep it inside conditioned space or protect it.

There is no corrosion resistant coating on this valve. The protection it does have is inherent to the material, a lead free cast copper silicon alloy body with a stainless steel strainer. For buried, exterior, or chemically aggressive service, specify a valve built for that duty rather than this standard-style unit.