Airtac PU Straight Fitting PU4
The AirTAC Airtac PU Straight Fitting PU4 is a genuine straight union for push-in tube connection, rated 0 - 1.0 MPa (0 - 10 kgf/cm2) with a 1.5 MPa proof pressure.
- TypeStraight union
- SeriesPU
- Working pressure0 - 1.0 MPa (0 - 10 kgf/cm2)
- Proof pressure1.5 MPa
- Temperature-20 to +70 °C
- No minimum order. A single piece can be ordered.
- Ready in 3–5 business days. That is the time we take to process the order and hand it to the carrier. Transit time after that depends on the destination.
About the Airtac PU Straight Fitting PU4
The PU4 is AirTAC's PU straight union from the resin one-touch fitting range: a plain tube-to-tube splice that joins two lengths of Dia 4 mm soft nylon or polyurethane tubing in a straight line. It carries no thread at all, so it needs no port, no sealant and no gasket - a pure in-line join. Push each tube firmly home and the chuck inside grips it against the stainless spring gasket; press the release ring and the tube frees again.
This is the standard resin/brass one-touch spec profile, not the metal BP line: working pressure 0-1.0 MPa (0-10 kgf/cm2), vacuum down to -750 mmHg (10 Torr), proof pressure 1.5 MPa and a temperature window of -20 to +70 C. The release button and chuck are POM over an aluminium-alloy guide, with an NBR O-ring sealing the grip. The body is grey as standard, and Dia 4 is the smallest bore this union is made in.
Airtac PU Straight Fitting PU4 Technical Specifications
| Model | Airtac PU Straight Fitting PU4 |
|---|---|
| Type | Straight union |
| Series | PU |
| Connection | Push-in one-touch |
| Working pressure | 0 - 1.0 MPa (0 - 10 kgf/cm2) |
|---|---|
| Negative pressure | -750 mmHg (10 Torr) |
| Proof pressure | 1.5 MPa |
| Temperature | -20 to +70 °C |
| Applicable tubing | Soft nylon or polyurethane tube |
| Thread standard | PT (Rc tapered) unless the code says otherwise |
POM release button and chuck, aluminium-alloy guide, stainless spring gasket, NBR O-ring; body brass or PBT depending on the part. AirTAC publishes flow as a characteristic curve rather than a single figure, so no L/min value is listed.
Model Code: Airtac PU Straight Fitting PU4
| PU | Straight union. |
|---|---|
| 4 / 6 / 8 / 10 / 12 | Tube outside diameter in mm (3.2 mm exists on the mini series). |
| M5 / 01 / 02 / 03 / 04 | Thread: M5x0.8, 1/8", 1/4", 3/8", 1/2" (M3 on the mini series). |
| D | Black. Blank = grey. |
Fitting & Sealing Notes
- check Cut the tube square and clean before pushing it home, or the seal will leak.
- check Push until it stops, then pull back to check the chuck has gripped.
- check To release, press the collet ring fully in and pull the tube out.
- check Threaded parts arrive with sealant on the thread; M5 sizes use a sealing gasket.
- check Match the tube OD exactly - a 6 mm fitting will not hold 1/4" tube.
Where the Airtac PU Straight Fitting PU4 Is Used
Mini gripper circuit splice
Repairing a cracked 4 mm nylon run feeding a small pick-and-place gripper cylinder, spliced in-line without occupying a spare port on the valve manifold.
Vacuum pick lines on lab equipment
Joining 4 mm polyurethane runs on small dispensing and analysis machines where the -750 mmHg (10 Torr) vacuum rating matters and the line is too tight for a threaded fitting.
Packed control cabinet repairs
Extending or rejoining a 4 mm signal-air line inside a crowded cabinet where the manifold has no free threaded port to accept a connector.
Is the Airtac PU Straight Fitting PU4 the Right Part?
Dia 4 is the bottom rung of the PU ladder - there is no smaller step, and the 3.2 mm mini size exists only on the PC and PL mini series, never on PU. The only neighbour is PU6 above it: stepping to Dia 6 buys you a larger bore and more capacity for the same run, at the cost of a physically larger fitting that your existing 4 mm tube will not fit. Tube OD must match exactly on both ends - a Dia 4 union will not grip 6 mm or 1/4 inch tube, and no shim or wrap will make it hold.
If you actually need to join 4 mm to a different diameter, that is a job for AirTAC's PG different-diameter straight union, not this part; if the run has to turn a corner, the PV union elbow is the shape to reach for instead.
Quick checklist
- ✓ Tube outside diameter matches exactly
- ✓ Thread size and standard match the port
- ✓ Working pressure within 0 - 1.0 MPa (0 - 10 kgf/cm2)
- ✓ Temperature within -20 to +70 °C
Airtac PU Straight Fitting PU4 FAQ
The PU4 is a straight union for Dia 4 mm soft nylon or polyurethane tube on both ends, with no thread. Working pressure is 0-1.0 MPa (0-10 kgf/cm2), it handles vacuum to -750 mmHg (10 Torr), proof pressure is 1.5 MPa, and the service temperature range is -20 to +70 C.
No. A one-touch union grips one exact tube OD per side, and the PU4 is Dia 4 on both ends. For a change of diameter in a straight run, use AirTAC's PG different-diameter straight union in the matching sizes; for a change of direction at the same size, the PV union elbow is the correct shape.
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1-Year Warranty
Covers non-human-caused product damage.
Fast Dispatch
Standard parts are processed and dispatched in 3-5 business days.
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Most inquiries answered within 7-8 hours.
Related AirTAC One-Touch Fittings
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