Quick-Connect Couplings for In-ProductionLine Air-Tightness Testing
Quick-Connect Couplings for In-Line Air-Tightness Testing
(also called quick-seal or quick-change fittings)
- Purpose
In 1–2 seconds, they create a leak-tight seal between the test item (engine housing, battery pack, plastic tube, etc.) and the leak-tester circuit, then release instantly after the test—keeping takt time short, leaks zero, and parts unscratched. - Typical Designs
a) Radial-expansion type
• Elastic seal ring expands against the inner wall of a smooth bore.
• Fits bore diameters with H7–H11 tolerance.
b) Face-seal (end-load) type
• Flat seal ring is pressed against the part’s end-face by an outer cone.
• Ideal for flanged ports or tube ends.
c) Quick-thread type
• Floating nut locks with a ¼-turn after insertion; self-compensates for thread pitch errors.
• Used on standard internal threads.
d) Push-to-connect sleeve type
• Slide sleeve forward → insert tube → release sleeve to lock; push sleeve again to release.
• Works on 4–20 mm OD rigid or flexible tubing.
e) Pneumatic clamp type (robot EOAT)
• Driven by cylinder or servo; adjustable compression and position sensor feedback.
• Suited for fully automated, mixed-model lines.
| Item | Summary |
|---|---|
| Purpose | Seal-test-release in 1–2 s; keeps takt time, zero leakage, zero scratches |
| Typical Designs | ① Radial-expansion ② Face-seal ③ Quick-thread ④ Push-to-connect sleeve ⑤ Pneumatic clamp |
| Key Specs | ≤ 1×10⁻⁴ mbar·L/s leak rate; 0–1 MPa proof pressure; ≥ 1 million cycles; –20 °C to 120 °C |
| Selection Guide | Interface type/size → test pressure → cycle time → environment |
| Installation & Care | Floating mount ±0.5 mm; daily grease; inspect seals monthly or every 10 k cycles; 40 µm upstream filter |
| One-liner | Pick the right quick coupling—seal in a second, release in a second—so the leak station never slows the line. |
- Key Specifications
- Leak rate: ≤ 1 × 10⁻⁴ mbar·L/s (helium)
- Operating pressure: 0–1 MPa (high-pressure versions to 3 MPa)
- Insertion cycles: ≥ 1 million
- Temperature range: –20 °C to +120 °C (with FKM or silicone seals)
- Repeatability: ±0.1 mm (robotic versions)
- Four-Step Selection
- Interface: bore, tube OD, or thread—what size and tolerance?
- Pressure: test pressure plus any surge.
- Takt: manual ≤ 3 s, automated ≤ 1 s; need venting on release?
- Environment: dust, oil mist, high heat? Choose 316 stainless + FKM seals.
- Installation & Maintenance
- Mount on a floating bracket to absorb ±0.3–0.5 mm part-position error.
- Lightly grease seals daily with silicone-based lubricant.
- Inspect seals every 10 000 cycles or monthly; keep 5 % spares in stock.
- Install a 40 µm upstream filter to prevent chips from damaging seal faces.
One-sentence takeaway
“For in-line leak testing, the right quick coupling seals in one second and releases in one second—match the interface, pressure and durability, and the leak station will never slow the line.”