Legend Valve 301-303 Dielectric Union 1/2 Inch Fnpt X Fnpt

Product Description

The LEGEND VALVE 301-303 is a 1/2-inch dielectric union designed to isolate dissimilar metals in plumbing systems and prevent galvanic corrosion at the joint. It connects using female NPT threads on both ends and is rated for 200 psi cold working pressure and a maximum temperature of 180 degrees F. This fitting is installed by licensed plumbers and pipefitters in both residential and light commercial applications wherever copper and steel piping meet at a connection point, such as at water heater supply and return lines.

This dielectric union is commonly used where galvanically dissimilar piping materials join — for example, where a copper distribution line connects to a steel threaded fitting or appliance port. It is well suited for water heater connections, boiler piping, and similar hydronic or domestic water installations that require a code-compliant break between unlike metals. The FNPT x FNPT configuration makes it compatible with standard threaded pipe installations in residential and light commercial settings.

Key Features

• Prevents galvanic corrosion by electrically isolating dissimilar metal piping at the joint
• Rated for 200 psi cold working pressure for use in standard domestic water systems
• Maximum operating temperature of 180 degrees F suits hot water supply applications
• Female NPT x Female NPT connection type for straightforward threaded installation
• 1/2-inch size fits common residential supply and appliance connection lines

Compatibility

Designed as an OEM-style replacement or new-installation dielectric union for 1/2-inch threaded plumbing connections in residential and light commercial domestic water and hydronic heating systems.

Installation Notes

Installation should be performed by a licensed plumber in accordance with local plumbing codes and the International Plumbing Code. Shut off the water supply and depressurize the line before disassembling or installing any union fitting. Use appropriate thread sealant or PTFE tape on all NPT connections and avoid overtightening, which can crack the dielectric insulating sleeve. Verify the fitting orientation and insulating components are intact before restoring pressure.

Technical Specifications

• Size: 1/2 inch
• Connection Type: FNPT x FNPT
• Cold Working Pressure: 200 psi
• Maximum Temperature: 180 degrees F
• Fitting Shape: Dielectric Union
• Country of Origin: Taiwan

Standard Information

• Brand: LEGEND VALVE
• Manufacturer Part Number: 301-303