Reliance Worldwide 04357 Straight Reducing Coupling

Product Description

The RELIANCE WORLDWIDE 04357 is a straight reducing coupling designed to connect tubing of two different outside diameters within a fluid or refrigerant line. This fitting transitions a 5/8 inch OD line down to a 3/8 inch OD line in a single inline connection with no change in flow direction. It is a common component in plumbing, HVAC, and refrigeration piping systems where a direct reduction is needed without adding bends or offsets. Licensed plumbers and HVAC technicians reach for this fitting when upsizing or downsizing tubing runs during installation, repair, or system modification work.

This straight reducer is suited for residential and light commercial applications where two tubing sizes must be joined inline. Typical use cases include connecting supply and return lines of differing diameters, adapting between sections of a refrigerant circuit, or completing a plumbing rough-in where tubing sizes change between fixtures and mains. The inline straight profile keeps the assembly compact and simplifies routing in tight spaces.

Key Features

• Straight inline profile with no directional change for clean, compact installations
• Reduces from 5/8 inch OD to 3/8 inch OD in a single fitting
• Suitable for fluid and refrigerant line applications in HVAC and plumbing systems
• OD sizing allows compatibility with standard tubing used across residential and light commercial work

Compatibility

Designed as an OEM-style straight reducing coupling for use with 5/8 inch OD and 3/8 inch OD tubing in plumbing and HVAC refrigerant line applications.

Installation Notes

Installation should be performed by a licensed plumber or HVAC technician following applicable local codes, including IPC and IFGC requirements where relevant. Shut off the water supply or recover refrigerant from the system before cutting into any existing line. Ensure tubing ends are cut cleanly, deburred, and fully seated before completing the connection. Do not overtighten or force fittings onto tubing that does not match the stated OD dimensions.

Technical Specifications

• Inlet OD: 5/8 inches
• Outlet OD: 3/8 inches
• Configuration: Straight Reducing Coupling

Standard Information

• Brand: RELIANCE WORLDWIDE
• Manufacturer Part Number: 04357