Vacuum vs. Pressure: Selecting the Right Flexible Connector for Pneumatic Conveying Systems

1. The Vacuum Challenge: Preventing Connector Collapse

In vacuum conveying, atmospheric pressure pushes inward on the sleeve wall. If the wall is too thin or unsupported, the connector collapses (suck-in), blocking material flow and potentially damaging upstream equipment.

• The SOSHH Solution — PU-10-VR: For vacuum beyond −50 mbar, specify the PU-10-VR deep-vacuum grade. Non-metallic high-elasticity polymer rings are housed in HF-welded exterior pockets, holding the bore open under full vacuum to −1000 mbar while keeping the product-contact surface 100% metal-free.
• Structural Integrity: The rings are external — the interior remains a smooth, cylindrical, crevice-free bore, so the connector resists suction without trapping powder or triggering metal detectors.

2. Positive Pressure and the Risk of “Pinholing”

Pneumatic conveying often involves high-velocity particles striking the connector walls. In positive-pressure systems, a single weak spot can become a pinhole leak, causing dust clouds and product loss.

• 40 MPa Tensile Strength: SOSHH polyether TPU delivers 40 MPa tensile strength and ~600% elongation, absorbing pressure surges without stretching or bursting.
• Abrasion Resistance: With DIN abrasion of 39.0 mg, the material resists the “sandblasting” effect of high-speed particles, preventing wall thinning over time. For abrasive powders, step up to PU-15 (1.5 mm wall, +0.70 bar / −120 mbar).

3. Airtight Sealing with Tool-Free Snap-In Technology

In pressure systems, the connection point is the most common leak site. Traditional hose clamps fail to provide an even 360° seal, especially under vibration.

• Leak-Free Performance: The SOSHH snap-in cuff is HF-welded slightly undersized, then stretches over a tapered stainless spigot to form a 360° radial compression seal — no clamps, no drilled holes, no torque settings.
• Zero Leakage: The result is a dust-tight, crevice-free connection that maintains the pressure differential required for efficient pneumatic conveying.

4. Static Safety in High-Velocity Lines

Friction between fast-moving particles and the connector wall generates static electricity. In a combustible-dust pneumatic line, this is an extreme explosion risk.

• Integrated Safety — PU-10-AS: For combustible or flammable powders, specify the anti-static grade. It is inherently static-dissipative polyether TPU with a surface resistivity of 10⁶–10⁹ Ω and volume resistivity of 4.02×10⁷ Ω tested per IEC 62631-3-1:2023 (SGS Report SHMR240801578301-1). Engineered for ATEX Directive 2014/34/EU, Zones 20/21/22 (IEC 60079-32-2).
• No Grounding Strap Required: Charge dissipates gradually and safely through the material itself — no internal wires, no external grounding strap across the joint.

Selection Table

5. Request Engineering Review

Conveying line giving you trouble? Send us your spigot OD, conveying mode (vacuum or pressure), working mbar/bar, powder type and temperature — we’ll confirm the correct sleeve + spigot configuration and return a watermarked 2D approval drawing within 24 hours. → Email: amin@soshh.com