Sometimes a pneumatic line just needs to keep going. No valve port, no gauge, no manifold. You need to join one tube to another, or split one line into two branches, in the smallest possible space. That is the job of a pneumatic union fitting. The PE-C mini tee union air pipe connector from Reayon Pneumatic does it with three push-in ports, zero threads, and a body small enough to fit inside tight machine frames.
This guide explains what union fittings are, how the PE-C mini tee union is built, which sizes and pressure ratings it offers, and when a union beats a threaded fitting.
What Is a Pneumatic Union Fitting?
A union fitting joins two or more runs of tube end to end. Unlike a male or female threaded connector, a union has no thread at all. Every port is a one-touch push-in port: the tube slides in, a stainless steel grip ring bites the outer diameter, and an O-ring seals the joint instantly.
A straight union (union connector) joins two tubes in line. A union tee has three identical ports, so it can split one air line into two branches or combine two returns into one. The PE-C mini tee union is the compact tee version: three matched ports on a body designed for confined spaces. Because there is no thread to tighten, a union joint also works as a quick repair point — cut out a crushed tube section, insert a union, and the line is back in service.
Key Features of the PE-C Mini Tee Union
Thread-free, all push-in ports. All three ports take tube directly. No PTFE tape, no wrench, no risk of over-tightening a small plastic thread.
Mini body for tight spaces. The reduced body size fits inside machine frames, control cabinets, and moving assemblies where standard fittings will not fit.
Identical ports on all sides. Every port is the same size and works the same way, so any leg can be the inlet. Orientation errors are impossible.
Wide size coverage. Metric tube OD from 3 mm to 16 mm and inch OD from 1/8 inch to 1/2 inch are available.
Fast release. Press the collet ring toward the body and pull the tube straight out. Rerouting a line takes seconds and the fitting is reusable.
100% tested. Every PE-C fitting is air-leak and pressure-tested before it leaves the Reayon Pneumatic factory.
Pneumatic Union Fitting Specifications
The table below summarizes the standard ratings for the PE-C mini tee union air pipe connector:
Property
Value
Product code
PE-C
Body material
Engineering plastic (PBT)
Grip ring
Stainless steel
Seal
NBR O-ring
Ports
3 × push-in, identical size (tee union)
Metric tube OD
3 mm, 4 mm, 6 mm, 8 mm, 10 mm, 12 mm, 16 mm
Inch tube OD
1/8", 5/32", 1/4", 5/16", 3/8", 1/2"
Operating pressure
0 to 150 PSI (0 to 1.0 MPa)
Operating temperature
0 to 60 °C
Media
Compressed air
Compatible tubing
PU, PA (nylon), PE, PP
Testing
100% tested before delivery
All three ports on a union tee must match one tube OD. Order, for example, PE-C 6 mm or PE-C 1/4 inch — never mix a 6 mm leg with a 1/4 inch leg, because the grip rings are sized for one outer diameter each.
Where Union Fittings Are Used
Union fittings appear wherever tube runs need to continue or branch without a threaded port:
Extending tube runs. When a machine is relocated or a line is lengthened, a straight or tee union splices the new tube in without re-terminating the whole circuit.
Emergency repairs. Cut out a damaged or crushed tube section and join the two good ends with a union. Downtime drops from hours to minutes.
Branching air lines. A union tee splits one supply line to two cylinders, two blow-off points, or two sensors without adding a threaded manifold block.
Inside machine frames. The mini body fits between rails, beams, and cable trays where a standard fitting would clash.
Lab fixtures and jigs. Fixture builders reconfigure air points often, and a reusable push-in union makes changes tool-free.
Sampling and instrument lines. Small 3 mm and 4 mm unions route low-flow air signals in panel wiring.
Union Fitting vs Threaded Fitting: Which One Do You Need?
Both are one-touch push-in fittings, but they solve different problems. Use this quick check:
Choose a union fitting when both ends of the joint are tube. Typical cases: splicing two tube runs, repairing a damaged section, or branching one line into two with a tee.
Choose a threaded fitting when one end must enter a component port — a valve, cylinder, FRL unit, or manifold. Typical cases: male elbow, male straight, or bulkhead connectors with BSPP, BSPT, NPT, or metric threads.
In practice most circuits use both. Threaded fittings terminate the lines at components; union fittings keep the lines running between them. If your design needs a threaded bulkhead that passes through a panel, see the MPMF bulkhead nickel-plated brass connectors for the metal version.
Why Choose Reayon Pneumatic for Union Fittings
Reayon Pneumatic is a factory-direct manufacturer of pneumatic fittings, not a trader. The PE-C mini tee union and the rest of the plastic push-fit range are produced in-house, which keeps material lots, port tolerances, and test records consistent across batches.
Metric and inch sizes in stock — tube OD 3 mm to 16 mm and 1/8" to 1/2"
100% air-leak and pressure testing on every fitting
Production capacity over 3,000,000 pieces per month
Custom sizes and OEM packaging supported on request
Export experience to Europe, America, Asia, and the Middle East
A union fitting joins two or more lengths of tube end to end without any thread. Each port has its own push-in collet and O-ring seal, so both tubes are inserted directly into the fitting body. It is used to extend a run, repair a damaged section, or split an air line into branches.
What sizes does the PE-C mini tee union fitting come in?
The PE-C mini tee union air pipe connector covers metric tube outer diameters from 3 mm to 16 mm and inch sizes from 1/8 inch to 1/2 inch. Because all three ports of a tee union must match, you order it by one tube OD, for example PE-C 6 mm or PE-C 1/4 inch.
When should I use a union fitting instead of a threaded fitting?
Use a union fitting when you need to join two tubes of the same size with no threaded port in between. Use a threaded fitting when the line must connect to a valve, cylinder, manifold, or FRL port. Union fittings are also the fastest way to repair a crushed tube section without re-plumbing the whole circuit.
What tubing works with PE-C mini tee union fittings?
They work with polyurethane (PU), nylon (PA), polyethylene (PE), and polypropylene (PP) tubing. Cut the tube square with a proper tube cutter and push it in until it bottoms out. Working pressure is 0 to 150 PSI at 0 to 60 degrees Celsius for compressed air service.
Does Reayon Pneumatic offer custom sizes and OEM service for union fittings?
Yes. Reayon Pneumatic manufactures union fittings in-house, tests every piece before delivery, and supports custom sizes, thread combinations, and OEM packaging. Standard orders ship from stock in metric and inch sizes, with factory-direct pricing for wholesale buyers.
Send us your tube size, the number of ports you need, and your monthly volume. Reayon Pneumatic will quote factory-direct pricing and can ship samples for testing. Wholesale and OEM orders are welcome.
