Flexible Connector Material Selection Guide
Summary: A flexible connector fails not because the sleeve is inherently weak, but because it was specified for the wrong operating condition. The three critical vectors that determine material choice are continuous operating temperature, chemical exposure, and static/pressure duty. Use this guide to match the correct SOSHH polymer family to your process before requesting a quote.
Material Codes at a Glance
PU10 — Standard Food-Grade Polyether TPU
- Wall thickness: 1.0 mm (Available up to 2.0mm)
- Temperature range: −20 °C to +110 °C
- Surface resistance: >10¹² Ω (Insulative)
- Food contact: FDA 21 CFR 177.2600 (Report: TQT4821B36E)
- Best for: General food and industrial powder transfer — vibratory sifters, screw conveyors, hoppers, packaging machines. Ideal for our standard Snap-In Flexible Connectors.
PUAS — Anti-Static Polyether TPU
- −20 °C to +110 °C
- Surface resistance: 10⁶ to 10⁹ Ω (Dissipative)
- Tested per: IEC 60079-32-2
- Food contact: FDA 21 CFR 177.2600
- Best for: Combustible dust areas (ATEX zones), fine organic powders, solvent-containing products, and any line where static accumulation must be controlled safely.
PUHT — High-Temperature Polyether TPU
- −20 °C to +150 °C
- Food contact: FDA 21 CFR 177.2600
- Best for: Hot powder discharge and hot-air lines where standard PU10 would reach its thermal softening limit.
PURF — Fibre-Reinforced Polyether TPU
- Construction: Polyether TPU featuring an embedded, high-tensile reinforcement layer.
- Best for: Surges in positive pressure or deep vacuum duties where additional dimensional stability and extreme burst resistance are mandatory.
PTFE — CNC-Machined Virgin PTFE Bellows
- Temperature range: −70 °C to +260 °C
- Sterilization: Fully compatible with 121 °C live Steam-In-Place (SIP).
- Chemical resistance: 100% inert to strong acids, bases, and aggressive solvents.
- Best for: API pharmaceutical loops, highly corrosive chemical transfers, and extreme temperature zones beyond TPU limits. Explore our High-Temp PTFE Bellows.
Silicone — Platinum-Cured Food-Grade Silicone
- Temperature range: −60 °C to +200 °C
- Characteristics: Highly flexible, odorless, non-toxic, and halogen-free.
- Best for: Hot-air handling, drying ovens, and food-grade thermal transport. Explore our Silicone Duct Connectors.
Selection Decision Path
Answer these questions in order to find your optimal material grade:
- Does your line run continuously above +150 °C?→ YES: Specify PTFE bellows.→ NO: Continue to question 2.
- Is your product a fine organic powder in a dust-hazardous area?→ YES: Specify PUAS (anti-static, 10⁶–10⁹ Ω).→ NO: Continue to question 3.
- Does your line run above +110 °C but below +150 °C?→ YES: Specify PUHT→ NO: Continue to question 4.
- Does your line operate under vacuum or above +0.5 bar positive pressure?→ YES: Specify PURF (reinforced).→ NO: Specify PU10 (standard grade).
- Do you handle strong acids, bases or polar solvents?→ YES: Specify PTFE bellows regardless of operating temperature.
Quick Comparison Table
| Material | Wall | Temperature Range | Surface Resistance | Typical Duty |
|---|
| PU10 | 1.0 mm | −20 to +110 °C | >10¹² Ω | General food / industrial bulk |
| PUAS | 1.0 mm | −20 to +110 °C | 10⁶–10⁹ Ω | Anti-static / ATEX zones |
| PUHT | 1.0 mm | −20 to +150°C | >10¹² Ω | High temperature transfer |
| PURF | 1.0 mm | −20 to +110 °C | >10¹² Ω | Pressure / vacuum surges |
| PTFE | Machined | −70 to +260 °C | Insulative | Chemicals / SIP / extreme temp |
| Silicone | 1.5 mm | −60 to +200 °C | Insulative | Hot air / drying ovens |
Frequently Asked Questions (FAQ)
Q: Which material should I choose for a milk powder line?
A: PU10 is normally the correct choice for standard milk powder transfer. If the powder is very fine and static is a concern in your plant, specify PUAS instead.
Q: Is the anti-static grade the same as adding a copper wire?
A: No. Surface dissipative behaviour is achieved through the polymer formulation itself. There is no wire to fatigue and no loose metal fragment that could enter your product stream.
Q: Can one material cover both high temperature and chemical resistance?
A: Yes — PTFE bellows cover both. They withstand −70 °C to +260 °C and are inert to strong acids, bases and solvents.
Q: Which grade is food-contact compliant?
A: All polyether TPU grades (PU10, PUAS, PUHT, PURF) are formulated from food-contact polyether TPU compliant with FDA 21 CFR 177.2600. Silicone is platinum-cured food-grade. PTFE is inert and widely used in food and pharmaceutical processing. Request the current test report reference for your chosen grade.
Q: Can I combine properties — for example, anti-static AND reinforced?
A: Yes. Contact us with your temperature, pressure and static requirements and we will specify the correct combination or recommend the closest standard grade.
