Airtac PG Reducing Union PG8-4
The AirTAC Airtac PG Reducing Union PG8-4 is a genuine different diameter straight for push-in tube connection, rated 0 - 1.0 MPa (0 - 10 kgf/cm2) with a 1.5 MPa proof pressure.
- TypeDifferent diameter straight
- SeriesPG
- 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 PG Reducing Union PG8-4
The PG8-4 is an AirTAC PG different diameter straight union - a tube-to-tube reducer with no port thread at all. The Dia 8 end grips 8 mm OD soft nylon or polyurethane tubing, the Dia 4 end grips 4 mm OD tubing, and the two bores step down inside a single in-line body. Both ends are one-touch: push the tube home until it bottoms, the internal chuck grabs the OD and the shaped seal does the sealing; press the release ring toward the body and the same chuck lets go for removal.
This is the resin profile, not the metal one: working pressure 0-1.0 MPa, negative pressure down to -750 mmHg (10 Torr), proof pressure 1.5 MPa and a temperature window of -20 to +70 C. Internals are a POM release button and chuck, an aluminium-alloy guide, a stainless spring gasket and an NBR O-ring. Unlike a threaded reducer, nothing here needs sealant - the whole joint is made with tubing alone, which is why it is the fastest way to change bore in the middle of a run.
Airtac PG Reducing Union PG8-4 Technical Specifications
| Model | Airtac PG Reducing Union PG8-4 |
|---|---|
| Type | Different diameter straight |
| Series | PG |
| 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 PG Reducing Union PG8-4
| PG | Different diameter straight. |
|---|---|
| 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 PG Reducing Union PG8-4 Is Used
Pick-and-place gripper pilot feed
On a robotic pick-and-place cell, run the Dia 8 side from the gripper manifold supply and let the Dia 4 side feed a compact suction or pilot line, dropping bore in-line without adding a threaded fitting or a second junction.
Packaging machine sensor air
Carton and blister packaging machines often power photo-eye air purges and small air jets from a Dia 8 header; the PG8-4 steps the header down to Dia 4 right at the sensor drop, keeping the run tidy behind the guard.
Printing line marking nozzles
On an ink or label printing line, feed the Dia 4 side out to a pneumatic marking nozzle or air knife while the Dia 8 side taps straight off the machine's main 8 mm airline, all through one push-fit joint.
Is the Airtac PG Reducing Union PG8-4 the Right Part?
Size it both ways before ordering. Step down from this part and the PG6-4 keeps the same Dia 4 branch but takes a Dia 6 supply - the right call when your feeder line is 6 mm and you only need the small drop to the actuator. Step up to the PG8-6 and you keep the Dia 8 supply but reduce to 6 mm instead of 4 mm, doubling the small-side bore for a hungrier branch. This Dia 8 to Dia 4 step is the wider jump in the family, so it suits circuits where the small line is a true pilot or signal feed rather than a power leg. There is no thread on this part; if the reduction has to land on a port instead of on tubing, a threaded reducing shape such as PKD is the alternative.
Match the tubing exactly on both ends. The Dia 4 side will not hold 1/4 inch (6.35 mm) tube and the Dia 8 side will not take 10 mm - each chuck only seats its own nominal OD. Using soft nylon or polyurethane in good condition also matters here, because a scored or oval tube end is the usual cause of a weeping push-fit.
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 PG Reducing Union PG8-4 FAQ
It joins Dia 8 mm tube to Dia 4 mm tube, both ends one-touch, with no port thread. Working pressure is 0-1.0 MPa (0-10 kgf/cm2), negative pressure goes to -750 mmHg (10 Torr), proof pressure is 1.5 MPa and the temperature range is -20 to +70 C. It is the resin profile, so it is rated 1.0 MPa at up to 70 C - unlike the BPC metal line, which trades down to 0.9 MPa but reaches 150 C.
No. Each one-touch end grips only its exact nominal OD, so the Dia 4 end accepts 4 mm tubing and nothing else - 1/4 inch (6.35 mm) will not seal and will pull out. If your tube is 5 mm or 6 mm, order PG6-4 instead; if the small side can be 6 mm rather than 4 mm, the PG8-6 gives you that step with the same Dia 8 supply end.
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