Airtac PU Straight Fitting PU4D
The AirTAC Airtac PU Straight Fitting PU4D 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 PU4D
The PU4D is an AirTAC PU straight union, a tube-to-tube one-touch fitting with a Dia 4 mm acceptor on each end and no thread anywhere on the part. Push soft nylon or polyurethane tubing into either port and the internal chuck grips it; press the POM release ring to free it again. The D suffix turns the whole body black instead of the standard grey, useful where grey fittings vanish against a machine's stainless or light-grey panels.
This is the resin spec profile, not the metal BPC line: 0-1.0 MPa working pressure, -750 mmHg (10 Torr) vacuum, 1.5 MPa proof pressure and -20 to +70 C. There is no threaded stud to seal, so the joint relies entirely on the tube landing square on the NBR O-ring over a stainless spring gasket - cut the tube clean and square or the union will weep.
Airtac PU Straight Fitting PU4D Technical Specifications
| Model | Airtac PU Straight Fitting PU4D |
|---|---|
| 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 PU4D
| 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 PU4D Is Used
SMT vacuum pen drop
Splicing two 4 mm vacuum lines at a pick-and-place head on a small PCB assembler, where the union's -750 mmHg rating covers the ejector's suction side.
Bench analyser air feed
Joining pump outlet to sensor block on a gas analyser rig, with the black body hiding discolouration from dye or marker traces around the fittings.
Split tube repair
Replacing a cracked 4 mm run on a lab fixture by splicing in a fresh length, no tube re-termination or new thread sealing needed.
Is the Airtac PU Straight Fitting PU4D the Right Part?
Dia 4 mm sits at the bottom of the PU ladder; the next step up is the PU6, whose wider bore carries visibly more flow to small actuators and longer branch runs. Note that AirTAC makes no Dia 3.2 mm union in this series - that tube size exists only on the PC and PL mini parts, so a PU4 cannot be downsized further. Whatever you order, tube OD must match exactly: a Dia 4 union will not hold 6 mm tube, and stretching smaller tube over the port cuts the O-ring on insertion.
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 PU4D FAQ
In one place: Dia 4 mm tube on both ends, no thread, black resin body (D suffix). Working pressure 0-1.0 MPa (0-10 kgf/cm2), proof pressure 1.5 MPa, vacuum down to -750 mmHg (10 Torr), temperature -20 to +70 C, tubing soft nylon or polyurethane.
Yes. Press the release ring to free the tube and push it back in to re-grip, but AirTAC publishes no cycle count, so treat every re-make as a fresh joint. Inspect the first 10 mm of tube for scores each time - a scratched surface at the NBR O-ring is the usual cause of a slow leak.
Authorized Export Seller
Genuine AirTAC parts produced by AirTAC factory.
1-Year Warranty
Covers non-human-caused product damage.
Fast Dispatch
Standard parts are processed and dispatched in 3-5 business days.
Fast Reply
Most inquiries answered within 7-8 hours.
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