American Vulkan LOKRING / Lokring Appliance Refrigerator LOKRING 8 NK AL 00 aluminum union coupling, 8 mm (5/16 inch) L13000506

Aluminum LOKRING union coupling for joining two sealed-system refrigerant tubes with the same approximately 8 mm (5/16-inch) outside diameter. The fitting is installed by swaging the rings over the tube ends using compatible LOKRING tooling.

Is This the Right Part?

Common Symptoms

• Reduced refrigerator or freezer cooling when the connection is leaking
• Long or continuous compressor operation associated with sealed-system refrigerant loss
• Visible oily residue or discoloration near the coupling, which may indicate a refrigerant-oil leak
• Tube movement, a displaced ring, or an improperly seated fitting at the connection

Check Before Replacing

• With the appliance unplugged and without disturbing the sealed system, visually inspect the coupling for cracked or displaced rings, tube movement, or an incomplete-looking connection.
• Check whether the fitting body and swage rings appear uniformly seated around the tube circumference.
• Look for oily residue or staining around the coupling; this is only a leak indicator and does not by itself confirm a failed part.
• Compare the installed fitting with the LOKRING visual acceptance checks: the fitting body should protrude beneath the drive ring, the INSPECT mark should be partly covered, and the drive ring should be seated against the fitting body.
• Do not cut, loosen, heat, pressurize, or recharge the sealed system during diagnosis; refrigerant-circuit testing and repair should be performed by a qualified technician.

Pro Tip

Part Details

Key Features

• LOKRING 8 NK AL 00 configuration
• Aluminum union coupling for same-size tubing
• Nominal tube outside diameter: approximately 8 mm (5/16 inch)
• Designed for permanent sealed-system tube connections
• Requires compatible LOKRING assembly/swaging tooling
• Used in refrigeration sealed-system service applications

Installation Notes

• Use only with tubing that matches the fitting size and material requirements; verify the tube outside diameter before assembly.
• Tube ends must be properly prepared, clean, straight, and free of burrs or damaging scratches before fitting installation.
• Use the specified LOKRING preparation compound and compatible assembly tooling according to the applicable manufacturer procedure.
• Keep both tube ends at the correct insertion depth and ensure the fitting is fully engaged in the assembly tool before actuation.
• Perform the manufacturer’s post-installation visual checks for fitting-body protrusion, INSTALL/INSPECT mark position, and drive-ring seating.
• Because this fitting is used in a refrigerator sealed system, refrigerant recovery, evacuation, pressure testing, and final charging should be handled by a qualified refrigeration technician.