Holyoke Fittings 42R-1210 Brass Flare Union 3/4 X 5/8

Product Description

The HOLYOKE FITTINGS 42R-1210 is a brass straight flare union designed to join two flare-end tubing connections in a single inline fitting. It accepts a 3/4-inch flare on one end and a 5/8-inch flare on the other, making it a reducing union suited for copper or aluminum tubing runs where two different tube sizes meet. Licensed HVAC technicians and refrigeration mechanics install this type of fitting during system assembly, repair, or when transitioning between line sizes in refrigerant or fuel gas piping systems.

This fitting is used in residential and light commercial HVAC, refrigeration, and gas piping applications where a leak-free mechanical flare joint is required. It is well suited for field repairs, line extensions, and new installations where tube sizes differ at a junction point. The straight union configuration keeps the fitting inline with the tubing run, simplifying routing in tight spaces such as equipment cabinets and utility chases.

Key Features

• Reducing straight union joins 3/4-inch flare to 5/8-inch flare in a single fitting
• Brass construction provides corrosion resistance suitable for refrigerant and gas service
• Flare-type mechanical connection requires no solder, torch, or open flame at the joint
• Inline straight body keeps tubing routing clean and minimizes pressure drop
• Compatible with standard 45-degree SAE flare tooling used in the trade

Compatibility

Designed as an OEM-style replacement or new-installation flare union for HVAC, refrigeration, and gas piping systems requiring a 3/4-inch by 5/8-inch straight flare union connection.

Installation Notes

Installation should be performed by a licensed HVAC technician, refrigeration mechanic, or plumber in accordance with applicable local codes and IFGC requirements for gas service or EPA Section 608 requirements for refrigerant systems. Recover all refrigerant and isolate the system before disconnecting or joining any refrigerant line fittings. Ensure tubing ends are properly flared with calibrated SAE 45-degree flare tooling before making up the joint — do not overtighten, as brass flare seats can be damaged by excessive torque. Inspect the flare seats for scoring or cracks before assembly.

Technical Specifications

• Size: 3/4 x 5/8 inches
• Type: Straight Union
• Connection Type: Flare

Standard Information

• Brand: HOLYOKE FITTINGS
• Manufacturer Part Number: 42R-1210