Push-In Union Connector SHPI PUC 08 — Straight, Ø8 mm Tube × Ø8 mm Tube, No Thread

Key Parameters

Technical Specifications

💡 Expert tip: before inserting the tube, confirm the end is cut square at 90° with no burrs — only a perpendicular cut ensures full seating against the NBR O-ring. A tube with an angled cut or burrs creates a micro-leak that is difficult to detect visually. Use a purpose-made tube cutter or pneumatic-tube scissors — not a knife.

Key Design Features

PBT body instead of brass. The polybutylene terephthalate (PBT) body is an engineering thermoplastic with high resistance to hydrocarbons, oils, and vibration. At equivalent mechanical strength it is 2–3 times lighter than brass, chemically inert to pneumatic working media, and requires no corrosion-protection coating. PUC 08 is the solution where low line weight matters: multi-axis manipulators, mobile installations.

Dual tube retention. The stainless grip ring claws work on the reverse-wedge principle: the harder the line pressure tries to push the tube out, the more firmly the claws grip it. This fundamentally distinguishes a push-in connection from simple friction retention — the fitting is more reliable under pulsating pressure and vibration.

Elliptical-profile release ring. SHPI uses a ring with an elliptical cross-section — when pressed, it evenly spreads the grip ring claws around the full circumference. Less force required to release, lower risk of tube damage during frequent reconnections.

Vacuum compatibility. Most push-in fittings are rated for positive pressure only. PUC 08 maintains a seal under vacuum to −100 kPa — required in pneumatic pick-and-place systems (vacuum suction cups, ejector systems).

SHPI PUC Series — Available Sizes

Cross-Reference by Brand

⚠️ Important: PUC 08 is a fitting for tubes of equal diameter (8 mm × 8 mm). To connect tubes of different diameters (e.g. Ø8 mm × Ø6 mm), use the PRUC series reducing union. Specify when ordering.

5 mandatory parameters to verify compatibility:

1. Tube outside diameter — must be exactly 8 mm. Ø5/16″ tubes (7.94 mm) are technically compatible, but verification is recommended.
2. Tube material — PU, PA12, PE, PVC. Silicone and rubber hoses are incompatible with the push-in grip mechanism.
3. Working pressure — up to 10 bar. Above 10 bar, use push-in fittings with a brass body.
4. Working temperature — 0–60°C. Versions with FKM seals are available for temperatures up to +100°C.
5. Medium — compressed air, vacuum, inert gases. Water (non-freezing) — permitted. Aggressive liquids — not applicable.

Why Acvatron SRL — 5 Solid Reasons

Original SHPI Products with Documentation

We supply genuine SHPI fittings (Taiwan, >40 years in the market) with invoice and ISO 9001 certificate of conformity. Not OEM copies, not unbranded product.

Complete Series in Stock

PUC 04 / 06 / 08 / 10 / 12 / 16 and related series (elbow PL, tee PT, Y-type PY, reducing PRUC) — held in permanent stock. We equip the full pneumatic line from a single supplier.

Compatibility with SHPI Tubing

PUC 08 works optimally with PU 8×5 mm tubing from the same SHPI manufacturer — guaranteed dimensional tolerance match on outside diameter and material hardness. We sell tube and fittings from the same product line.

Stock in Chisinau

Standard sizes are held in permanent stock. Same-day dispatch for orders placed before 14:00.

Technical Support for Selection

Send us your pneumatic line schematic or list of connection points — we will select a complete fitting set (straight, elbow, tee, reducing) in one order, with no repeat orders.

Applications

Industrial Automation and Robotics

• Routing pneumatic lines to cylinders and valves
• Splicing tubes in pneumatic islands and cable ducts
• Repairing damaged sections of pneumatic runs without replacing the full line

Vacuum Systems and Pick-and-Place Devices

• Connecting ejector system and vacuum suction cup lines
• Distribution to multiple suction points on manipulators
• Part transport systems on conveyors

Woodworking and Furniture Manufacturing

• Pneumatic lines to presses and clamping fixtures
• Vacuum workpiece clamping systems on machining centres

Food and Packaging Industry

• Pneumatics of dosing and filling machines
• Pneumatic valve and gate drives on process lines

Medical and Laboratory Equipment

• Pneumatic lines in analytical instruments
• Inert gas lines in laboratory installations

Expert Opinion

“PUC 08 is the most ‘invisible’ fitting in a pneumatic system: when it works correctly, nobody thinks about it. Problems show up in two situations. First — the tube isn’t pushed in all the way. The grip ring only locks the tube after it has passed through the O-ring to the internal stop inside the body. A half-inserted tube is held by the grip ring alone without sealing — that’s a leak at pressures above 3–4 bar. Second — incompatible tube material. Soft-wall PVC hose gets deformed by the grip ring: the tube is ‘cut into’ by the claw, it holds, but loses structural integrity. Check tube stiffness — for PUC you need a rigid polyurethane or nylon tube, not a soft hose.”

Vitalie Bolucevski, Chief Engineer, Acvatron SRL — 15 years in the industry

Applicable standards:

• ISO 9001 — SHPI quality management system
• JIS B 8381 — Japanese standard for pneumatic push-in fittings (SHPI series is compatible)
• ISO 6945 — tubing for pneumatic systems (compatible tubes PU / PA12)

How to Select the Right Push-In Union Connector: 5-Step Guide

1. Measure the tube outside diameter. Not the inside diameter, not by feel — measure the outside diameter with calipers. For PUC 08 — exactly 8.0 mm. If the diameter is 10 mm — PUC 10 is required.
2. Identify the connection type. Straight (tube-to-tube) → PUC. With threaded outlet → PS (straight) or PL (elbow). Tee → PT. Y-type → PY.
3. Check the tube material. PU, PA12, PE — compatible. Soft PVC hose — not compatible; the grip ring deforms its wall. A tube with rigid walls is required.
4. Check the working pressure. Up to 10 bar — PBT body of PUC 08 is sufficient. Above 10 bar — select fittings with a nickel-plated brass body.
5. Calculate quantity and related types. One PUC 08 per straight tube-to-tube joint. Angled bends → PL. Branch points → PT. Do not mix fittings from different manufacturers on the same tube — outside diameter tolerances may differ.

FAQ

❓ What is the difference between PUC 08 and PU 08 — aren’t they the same?

No. PUC 08 is a tube-to-tube straight union connector: two push-in ports, no thread, for joining two Ø8 mm tubes. In SHPI’s part numbering, PUC means union straight (straight connector without thread). PS means male straight connector (with thread). Specify the type when ordering: “union straight” — PUC; “male straight with thread” — PS.

❓ Can SHPI PUC 08 be used for water or food-grade media?

For water without freezing — permitted. For food-grade media — no: the PBT body and NBR seal do not carry a food-grade certification. For food applications, use stainless steel fittings with FKM seals, or contact us for a specialised solution.

❓ Where can I buy the SHPI PUC 08 push-in union connector in Moldova?

The SHPI PUC 08 push-in connector (straight, Ø8 mm × Ø8 mm, PBT body, NBR seal, 10 bar, vacuum-rated) is in stock at Acvatron SRL, Chisinau. The full SHPI PUC series (04, 06, 08, 10, 12, 16 mm) is available. Contact us at acvatron.md or WhatsApp.