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Entity-Dense Summary:
A pneumatic conveying flexible connector is a resilient sleeve installed between conveying line sections, feeders, rotary valves, and receiving equipment. Pneumatic conveying subjects the connector to three combined operational loads: positive pressure, negative pressure (vacuum), and electrostatic charge generated from continuous powder-to-wall friction. Selecting the correct grade depends on which load dominates the process — pressure duty requires the PU-15 or fiber-reinforced PURF, vacuum duty requires the PU-10-VR rated to −1000 mbar, and combustible dust environments require the inherently static-dissipative PU-10-AS (10⁶–10⁹ Ω). All TPU grades are fully FDA 21 CFR 177.2600 compliant.
Pneumatic conveying is the only powder-handling application that combines pressure, vacuum, and static charge within a single operational span. Each load attacks the flexible connector differently:
| LOAD | WHAT IT DOES TO THE SLEEVE | CONSEQUENCE |
|---|---|---|
| Positive pressure | Balloons the wall outward | Wall overstretches, loses elasticity, and tears |
| Negative pressure (vacuum) | Pulls the wall inward | Wall collapses, choking the material flow |
| Static charge | Accumulates on insulating walls | Creates an ignition/spark risk with combustible dust |
A standard sleeve rated for only one of these conditions will fail when exposed to the other two. Selection must begin by identifying which operational load dominates your conveying line.
Path 1 — Positive Pressure Dominant
Dilute-phase or dense-phase conveying pushes powder under positive pressure. The connector wall must actively resist outward ballooning.
Path 2 — Vacuum Dominant
Vacuum conveying pulls powder through the line under negative pressure. The connector must resist inward collapse to prevent flow restriction.
Path 3 — Static Dominant (Combustible Dust)
Pneumatic conveying inherently generates high electrostatic charges through powder-to-wall friction. For combustible dust, the sleeve must bleed this charge safely to earth.
(Note: For a line with two or three loads combined—such as heavy vacuum plus combustible dust—contact our engineering team. A single-grade off-the-shelf selection may not cover multiple extreme loads simultaneously).
Static dissipation acts as a complete system, not just a standalone sleeve. To safely eliminate static in a pneumatic line:
The PU-10-AS is inherently static-dissipative. The property is built directly into the TPU formulation, meaning there is no surface coating to wear off under high-velocity abrasion and no internal wire to break under vibration.
| FAILURE MODE | DOMINANT LOAD | THE ENGINEERED FIX |
|---|---|---|
| Ballooning / overstretch | Positive pressure | PU-15 (+0.70 bar) or PURF (300 MPa) |
| Collapse / choked flow | Vacuum | PU-10-VR (−1000 mbar) |
| Spark / ignition risk | Static accumulation | PU-10-AS (10⁶–10⁹ Ω) |
| Wall abrasion | High-velocity powder | PU-15 (1.5 mm thicker wall) |
| Softening / melting | High temperature | PU-HT (−20 to 150°C continuous) |
| CONVEYING CONDITION | RECOMMENDED GRADE | KEY SPECIFICATION |
|---|---|---|
| General powder, low pressure | PU-10 Standard | 1.0 mm, +0.35 bar / −50 mbar |
| Abrasive / high-velocity powder | PU-15 | 1.5 mm, +0.70 bar / −120 mbar |
| Combustible dust | PU-10-AS | 10⁶–10⁹ Ω, ATEX Zones 20/21/22 |
| Full vacuum suction | PU-10-VR | −1000 mbar rating |
| High pressure pulse | PU Fiber-Reinforced (PURF) | 300 MPa tensile strength |
| High temperature (≤150°C) | PU-HT | −20 to 150°C continuous service |
(For strong chemical media or temperatures exceeding 150°C, standard TPU grades are not suitable. Please contact us for PTFE corrugated bellows).
To ensure perfect fitment and operational safety, please provide these eight parameters to our engineering team:
Send these details to amin@soshh.com for CAD verification and precise grade selection. See our How to Measure & Size Guide.
Q1: Can one connector handle pressure, vacuum, and static at once?
A: Not always from a single off-the-shelf grade. Each grade optimizes one dominant load — pressure (PU-15/PURF), vacuum (PU-10-VR), or static (PU-10-AS). For combined extreme loads, contact our engineering team for a paired solution.
Q2: What is the vacuum rating for pneumatic conveying?
A: The PU-10-VR is rated to −1000 mbar full vacuum, making it ideal for aggressive suction conveying. The PU-15 can handle up to −120 mbar partial vacuum.
Q3: Do I need anti-static connectors for pneumatic conveying?
A: If the powder is combustible, yes. Pneumatic conveying generates exceptionally strong static charges due to continuous friction. You must specify the PU-10-AS (10⁶–10⁹ Ω surface resistivity, ATEX Zones 20/21/22).
Q4: What pressure can a conveying connector handle?
A: The PU-15 safely handles up to +0.70 bar. For high-pressure pulses or system surges, specify the PU Fiber-Reinforced (PURF) grade, which features a massive 300 MPa tensile strength.
Q5: Why does a conveying connector balloon or collapse?
A: Positive pressure forces the wall outward (ballooning), while vacuum pulls it inward (collapse). Using standard sleeves on high-load lines causes premature failure. The correct reinforced grade resists its dominant load — PU-15 for pressure, PU-10-VR for vacuum.
Q6: Are these conveying connectors food-contact compliant?
A: Yes. All SOSHH TPU grades are FDA 21 CFR 177.2600 compliant (Report TQT4821B36E) and formulated in accordance with EC 1935/2004 and EU 10/2011.
SGS Certified FDA Compliant Food Safe
SGS certified PU flexible connection supplier
Tested for ATEX Antistatic Requirements
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FDA 21 CFR 177.2600 Compliance
