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Brass 3/8 inch flare union fitting for HVAC systems

Mueller

Mueller A 327 3/8" Access Valve Union HVAC Control

SKU CH-PJMH-0KRAJ

A brass refrigeration coupling that joins two 3/8" flare connections for HVAC service access

  • Brass construction resists corrosion for long service life
  • 3/8" flare-to-flare union connects refrigerant lines directly
  • Access valve allows system charging without extra fittings
  • Model 327 identifies the exact Mueller replacement part

Mueller A 327 3/8" Access Valve Union

The Mueller A 327 is a brass refrigeration fitting designed to join two 3/8-inch flare connections in a straight union configuration. It serves HVAC technicians and installers who need a reliable coupling for system assembly or repair work. The brass construction provides corrosion resistance suitable for refrigerant handling. This control component integrates directly into existing flare piping without adaptation.

Suits flare-to-flare piping requirements

This union suits professionals joining identical 3/8-inch flare ends during installation or maintenance of refrigeration circuits. It is not intended for connections involving different thread sizes, pipe diameters, or non-flare fitting types. Buyers needing reducer unions, elbow configurations, or alternative connection methods should look at other fitting styles. The component addresses a specific straight-coupling need only.

How it compares

Measured against everything we stock in Heating & Cooling Controllers, at today’s prices. Recalculated every night.

Price $1.71
Cheaper than about 99% of the 1,762 comparable items (median $45.99).

Specifications

Product
Brand nameMUELLER

Questions about this item

How do I install the 3/8" flare union without damaging the brass threads?

Clean both flare faces, hand-tighten each nut until the seats touch, then finish with a wrench — about one-sixth turn past snug — so the soft brass seals without galling or cracking the flare.

Will the brass union need replacement if the system is converted to a different refrigerant later?

Brass is compatible with common HFC, HCFC and HFO refrigerants and their oils, so a refrigerant change alone does not require swapping the union; only physical damage or corrosion would mandate replacement.

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