Watts 3L-150 3/4 3/4 In Brass Poppet Type Pressure Relief Valve, 150 psi, Test Lever

The Watts 3L-150 3/4 takes 3/4 inch NPT on both ends. The inlet is male threaded and the outlet is female threaded, so it threads straight into a 3/4 inch NPT tapping on the tank or header, and you run your discharge piping off the female outlet. No adapters needed if your tapping is 3/4 NPT.

Pressure only. The 3L-150 is a poppet type pressure relief valve with a protection type of pressure, set to relieve at 150 psi. If you are protecting a domestic water heater and code requires combined temperature and pressure protection, this is not the valve for that job, you need a T&P valve instead. The 3L belongs on boilers, tanks and piping where overpressure is the hazard being guarded.

It is factory set to relieve at 150 psi and is not a field adjustable setting. The 3L series covers a 75 to 150 psi range across the line, so if your system needs to pop at a lower pressure you order a different setting in the series rather than changing this one. Pick the setting at or below the maximum allowable working pressure of the vessel you are protecting.

The 3L-150 3/4 is rated for 370,000 BTU per hour of steam discharge capacity. Compare that against the input rating of the appliance or vessel you are protecting: the relief valve's capacity has to equal or exceed the heat input. If your boiler input is above 370,000 BTU/hr, step up to a larger valve.

No. The 3L-150 3/4 is not lead free, so it should not be installed on potable water systems where lead free construction is required. Use it on non potable service such as heating boilers and steam or hot water equipment. For a potable application, choose a valve specifically marked lead free.

Those are two different numbers and both matter. 150 psi is the relief setting, the point at which the valve discharges. 113 psi is the maximum working pressure, the normal system pressure the valve is rated to sit at without weeping. Size your system so operating pressure stays at or under 113 psi and you keep clear margin below the 150 psi pop point.

It is flagged Buy American Act compliant with USA origin, which is what a government, school or healthcare procurement officer needs to see on the submittal. The orderable part number is 3L-150 3/4, Watts part 11917.

Plan for the discharge line. The 3/4 inch NPT female outlet on the 3L-150 has to be piped full size to a safe point of discharge, with no valve or restriction between the relief valve and the vessel it protects. You will also want pipe dope or tape rated for the service on the 3/4 inch male NPT inlet threads. Install the valve upright in the vertical position typical for poppet relief valves.