Overview

PEEK (Polyether Ether Ketone) tubing is commonly used in HPLC, UHPLC, and laboratory fluid transfer applications because of its excellent chemical resistance, biocompatibility, and pressure-handling capabilities.

Although PEEK tubing is flexible compared to stainless steel tubing, it should not be bent below its recommended minimum bend radius. Excessive bending can deform the tubing, restrict flow, increase backpressure, or damage the tubing wall.

Understanding the proper bend radius is important when routing tubing through instrument compartments, valve assemblies, and detector modules.

Recommended Bend Radius

For 0.0025" ID × 1/16" OD PEEK tubing, the recommended minimum bend radius is approximately:  25 mm (1 inch) radius

This corresponds to a bend diameter of approximately:  50 mm (2 inches)

Maintaining this radius helps preserve the internal geometry of the tubing and supports reliable fluid flow.

Why Bend Radius Matters

When tubing is bent too tightly, several issues can occur:

• Tubing deformation
• Internal flow restriction
• Increased system backpressure
• Reduced flow consistency
• Premature tubing failure
• Potential leaks at fitting connections

These effects can negatively impact chromatographic performance and system reliability.

Routing PEEK Tubing in HPLC Systems

When installing tubing:

• Avoid sharp bends.
• Create smooth routing paths.
• Leave sufficient clearance around fittings.
• Avoid pulling tubing under tension.
• Verify that tubing does not contact moving instrument components.

Proper routing helps maintain flow path integrity and extends tubing service life.

Comparison to Other Tubing Materials

PEEK tubing offers greater flexibility than stainless steel tubing while maintaining excellent pressure resistance for many analytical applications.

Benefits include:

• Easy installation
• Chemical resistance
• Biocompatibility
• Electrical insulation
• Low dead volume connections

However, like all polymer tubing, PEEK performs best when operated within recommended mechanical limits.

Best Practices

For maximum tubing performance:

• Maintain at least a 25 mm bend radius.
• Avoid repeated bending at the same location.
• Inspect tubing for flattening or distortion.
• Replace damaged tubing promptly.
• Verify fittings remain properly seated after installation.

Following these practices can help improve reliability and reduce troubleshooting.

Key Takeaways

• The recommended minimum bend radius for 0.0025" ID × 1/16" OD PEEK tubing is approximately 25 mm.
• This corresponds to a bend diameter of approximately 50 mm (2 inches).
• Excessive bending can restrict flow and damage the tubing.
• Proper routing helps maintain chromatographic performance and tubing longevity.
• Smooth bends are preferred over sharp turns in all HPLC fluidic systems.

Additional Resources

For tubing dimensions, pressure ratings, fitting compatibility, and installation guidance, view:

• PEEK Tubing Specifications and Selection Guide