A.Y. McDonald 5121 Lead-Free F...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$80.00
A.Y. McDonald 5121 Lead-Free Flare Union Fitting, 1-1/4" Coupling

A.Y. McDonald 5121 Lead-Free Flare Union Fitting, 1-1/4" Coupling

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Model: 5121-147

In Stock (leaves warehouse same day if ordered before 3pm ET)

$80.00
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A.Y. McDonald 5121 Lead-Free Flare Union Fitting, 1-1/4" Coupling

The A.Y. McDonald 5121 Flare Union is a 1-1/4" lead-free (LF) fitting engineered to join two flare-end pipe or tube runs into a single, leak-resistant connection. Designed for professional plumbing and utility installations, this union offers a reliable, code-conscious solution wherever a secure flare-to-flare joint is required. Configured as a 501-style flare union, the 5121 allows two flare-end lines to be joined — and later disconnected without cutting the pipe — simplifying future maintenance and service work. A.Y. McDonald backs the 5121 series with published manufacturer specifications (reference spec sheet 5121-148), giving contractors and installers confidence in fit, performance, and traceability for every job.

Key Features

  • Trade Size: 1-1/4" connection sized for compatible flare-end pipe and tube runs.
  • Lead-Free (LF) Construction: Manufactured to meet lead-free requirements for potable water and utility applications.
  • Flare Union Design: A true union configuration allows two flare-end lines to be joined and later disconnected without cutting the pipe, simplifying maintenance and future service work.
  • 501 Flare Union Fitting Type: Purpose-built flare-to-flare connection style for dependable, serviceable joints.
  • Documented Specifications: Full dimensional and performance data available via the A.Y. McDonald 5121-148 manufacturer spec sheet for engineering and submittal review.
  • Professional-Grade Fitting: Suited for plumbing and light industrial piping systems requiring a dependable flare connection.

Technical Specifications

  • Model: 5121
  • Trade Size: 1-1/4"
  • Fitting Type: 501 Flare Union
  • Lead-Free Designation: LF
  • Product Type: Coupling
  • Reference Spec Sheet: 5121-148

Typical Applications

  • Potable Water Service Line Connections
  • Residential and Commercial Plumbing Installations
  • Utility and Meter Piping Runs
  • Flare-to-Flare Pipe or Tube Joints
  • Maintenance and Serviceable Line Connections

Why A.Y. McDonald?

A.Y. McDonald has a long-standing reputation for producing durable, code-compliant waterworks and plumbing fittings. The 5121 Flare Union is manufactured to lead-free standards and supported by manufacturer-published specifications, giving contractors, engineers, and installers a dependable, well-documented component for their piping systems. Its 1-1/4" flare union design lets crews assemble and later service flare-to-flare connections without cutting into existing pipe runs, reducing labor and downtime on repair or retrofit work. Choosing A.Y. McDonald means selecting a fitting built for reliable, serviceable performance in demanding plumbing and utility applications, backed by documented specifications (5121-148) that engineers and installers can reference for submittals and system design.

Manufacturer Resources

Spec Sheet

Product Specs

Product Subgroup:
Pipe Fittings
Product Group:
Plumbing
Department:
Plumbing
Product Type:
Coupling

A.Y. McDonald 5121-147 – Frequently Asked Questions

1) What sizes does the A.Y. McDonald 501 flare union come in?
Two sizes: 1 inch (part 5121-147) and 1-1/4 inch (part 5121-148). Order by the tubing size you're joining, since a flare union has to match the tube OD on both ends.
2) Is the A.Y. McDonald 501 flare union lead free for potable water service?
Yes, the 501 flare union is designated LF, lead free. That's the version water utilities and plumbers need for potable service lines.
3) Can I use the 1-1/4 inch 501 union to join a 1 inch tube to a 1-1/4 inch tube?
No. The 501 is a straight union, same size on both ends, so 5121-148 takes 1-1/4 inch flared tube on both sides and 5121-147 takes 1 inch on both. To step between 1 inch and 1-1/4 inch you need a reducing flare coupling or a flare adapter pair, not this union.
4) What does a flare union like the McDonald 501 actually connect, and do I need anything else to make the joint?
It's a straight coupling that joins two runs of flared tubing, typically copper or plastic service tubing, end to end. The union body supplies the seats and the nuts; you supply the tube and the flare. Each tube end has to be properly flared with a flaring tool before assembly, and on plastic tubing an insert stiffener is required so the flare holds under the nut. No solder, no threading of the pipe itself.
5) Should I use a flare union or a compression union on a water service line?
Flare, like the 501, is the utility standard for buried and pit-set service connections: the joint is metal to metal, it can be taken apart and remade, and it doesn't rely on a gasket. Compression is faster in the field and doesn't need a flaring tool, but flare is what most water departments specify for tubing in the ground. If your spec sheet or inspector calls for flare, a compression union is not an accepted substitute.
6) I'm replacing a leaking union on an existing 1 inch copper service. Will the 5121-147 work?
If the existing tube ends are flared to 1 inch, yes, the 5121-147 drops into that joint. Inspect both flares first, though: an old flare that's cracked, out of round, or scored will keep weeping no matter what union you put on it. Cut it back and reflare, and keep enough slack in the tube to do that before you commit to the repair.
7) What is the exact manufacturer part number for the 1-1/4 inch A.Y. McDonald flare union?
5121-148. The 1 inch is 5121-147. Both are A.Y. McDonald 501 series flare unions in the lead free configuration.
How fast can I get the A.Y. McDonald 5121-147 delivered?
Most orders ship the same day from our distribution partners, with quick delivery throughout the continental U.S. Need it urgently? Contact Us for expedited shipping options.
Can I return it if it doesn’t work for me?
Yes—ZenSupply offers a hassle-free return policy. If the product isn’t the right fit, reach out to our support team for a return authorization or setup a return by following our return instructions.
Does the A.Y. McDonald 5121-147 come with a warranty?
Absolutely. The A.Y. McDonald 5121-147 is backed by a manufacturer’s warranty. For full warranty terms, check the product documentation or Contact Us.
How do I get technical support or installation help for the A.Y. McDonald 5121-147?
You can call, text, or email our expert support team for fast answers. We’re here to help with product selection, installation tips, and troubleshooting. Contact Us
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