Unions

Red-White Unions — Dielectric, Hydronic & Union Ball Valves

Red-White unions cover the transitions and service points that keep piping serviceable: lead-free brass dielectric unions, DZR hydronic unions with air vent and test point options, PEX unions, steam radiator unions, and union ball valves. PVFPro stocks them all with fast shipping from multiple U.S. warehouses, with real specifications on every product page.

What Is a Pipe Union?

A union is a threaded fitting that joins two pipe sections and can be taken apart without cutting pipe. One side screws into the other through a union nut, so piping, valves, and equipment can be serviced or replaced without unthreading the whole run. Red-White unions cover the two jobs contractors actually use them for: dielectric transitions between dissimilar metals, and break-away service points in hydronic, PEX, and steam radiator systems.

Red-White Union Families

1900AB dielectric unions — Lead-free brass to steel, NSF/ANSI 61 and 372 certified, ANSI/ASME B16.39. Steel and zinc-plated components isolate dissimilar metals to prevent galvanic corrosion at the transition. 1920AB offers NPT x press end configurations.
8050E / 8050P / 8050S / 8050T union ball valves — DZR lead-free brass full port ball valves with union bodies, in FNPT x FNPT and EzPress x FNPT end combinations, with chrome-plated balls and PTFE seats.
92-series DZR hydronic unions — DZR brass union bodies including a union with manual air vent and test point (92UN), MNPT x PEX F1960 unions, and PEX union ball valves with blow-out proof stems.
Steam and radiator unions — Brass (ASTM B283 C37700) steam radiator valves and radiator union elbows with FNPT x male union ends, plus matching union fittings for radiator supply connections.

Applications

Dielectric transitions between copper and steel pipe in potable water systems
Service break points ahead of pumps, valves, and water heaters
Hydronic heating systems where unions with test points support air management and system checkout
PEX connections between pipe and threaded components (ASTM F1960)
Steam and hot water radiator supply piping
Union ball valve installations where future valve replacement must be possible without re-piping

How to Choose the Right Union

Match the metals. Where copper meets galvanized or black steel, use a dielectric union to prevent galvanic corrosion.
Pick the end connections. FNPT x FNPT for all-threaded runs, press ends for copper press systems, PEX F1960 tails for PEX tubing.
Consider a union ball valve. If the union sits at an isolation point, a union ball valve gives you shutoff plus a break-away joint in one body.
Check the certification for potable work. The lead-free AB series carry NSF/ANSI 61 and 372.

Technical Specifications Overview

1900AB dielectric unions: Lead-free brass body side against zinc-plated steel (ASTM A105) components; certified to ANSI/ASME B16.39 with NSF/ANSI 61 and 372 lead-free listings. 1920AB adds NPT x press end options.
8050E/P/S/T union ball valves: DZR lead-free brass (ASTM B927 C27453) bodies, chrome-plated LF brass balls, virgin PTFE seats; FNPT x FNPT and EzPress x FNPT end combinations.
92-series hydronic unions: DZR brass (UNS C35330) bodies; PEX unions to ASTM F1960; union ball valve models to MSS SP-110 with blow-out proof stems; 92UN ships with manual air vent and test point.
Steam and radiator unions: Brass (ASTM B283 C37700) bodies and union nuts with FNPT x male union ends.
Threads: NPT to ASME B1.20.1 across threaded models.

Why dielectric matters: when copper pipe meets galvanized steel in a wet system, the two metals form a galvanic couple and the steel side corrodes. A dielectric union breaks that electrical path with a non-conductive barrier between the brass and steel halves, which is why plumbing codes call for them at dissimilar-metal transitions.

Frequently Asked Questions

When do I need a dielectric union? Anywhere dissimilar metals — typically copper to galvanized steel — meet in a wet system. Without it, galvanic corrosion attacks the joint.
Can a union valve replace a valve plus union? Yes. A union ball valve provides shutoff with a union nut on one side, so the valve can be serviced without disturbing the piping.
What is the union with air vent and test point for? It is used in hydronic systems where the same joint provides a break-away connection, a point to bleed air, and a port to verify system pressure.
Are these rated for potable water? The AB lead-free brass series are NSF/ANSI 61 and 372 certified. Confirm the listings on the specific product page.
Union or coupling? A solder coupling makes a permanent joint — the pipe has to be cut to come apart. A union is designed to unscrew, so use a union wherever a component downstream may need to come out for service.