Introduction to PTFE Capillary Tubing

PTFE Capillary Tubing refers to tubing with a very small inner diameter (typically less than 1 mm) made from Polytetrafluoroethylene (PTFE) resin through specialized processing techniques like paste extrusion. As its core material is PTFE, it perfectly inherits almost all the excellent properties of PTFE. Combined with its miniature capillary size, it becomes an indispensable critical component in high-end industrial and scientific research fields.

 

Core Material: Properties of Polytetrafluoroethylene (PTFE)

To understand PTFE capillary tubing, one must first appreciate the exceptional properties of PTFE (commonly known as "Teflon" or the "King of Plastics"):

1. Extreme Chemical Inertness: Resists attack by almost all strong acids, strong alkalis, strong oxidizers, and organic solvents, including aqua regia and hydrofluoric acid. This is its core advantage.

2. Excellent High & Low-Temperature Performance: Has an extremely wide continuous service temperature range from -190°C to +260°C, maintaining stable performance at extreme temperatures.

3. Outstanding Non-stick Properties & Low Coefficient of Friction: The surface is smooth, barely adhering to any substance, and has a very low coefficient of friction, resulting in minimal fluid resistance.

4. Superb Electrical Insulation: Non-conductive, with excellent dielectric properties, maintaining good insulation even in high-frequency or high-temperature environments.

5. High Purity & Biocompatibility: The material is pure, contains no additives, is non-toxic, and is biologically inert, making it suitable for medical devices and the food industry.

6. Weatherability: Resists aging and is unaffected by UV light and ozone.

 

Manufacturing Process

PTFE capillary tubing is primarily manufactured using Paste Extrusion (Push Processing). PTFE fine powder resin is mixed with an extrusion aid (e.g., a petroleum solvent), preformed into a billet, and then forced through a precision die under pressure to form the tube shape. Subsequently, it undergoes drying and sintering (heating to a high temperature where the PTFE particles coalesce and melt) to set its final form, creating tubing with a very precise, tiny inner diameter.

 

Key Features & Advantages

Combining PTFE properties with the capillary form, its main features include:

· Precise Micro-Diameter: Inner diameters can be made very small and precise, ranging from a few millimeters down to tens of micrometers (μm).

· Good Flexibility: The tubing is soft and flexible, easy to bend and coil, facilitating routing in confined or complex spaces.

· Very Low Fluid Resistance: The smooth, non-stick inner wall is ideal for transferring viscous, crystallizing, or particle-laden fluids, minimizing clogging risks.

· Inert Flow Path: Ensures liquids or gases passing through are not contaminated by metal ions, maintaining high sample purity.

· Semi-Transparency: Some PTFE tubing is semi-transparent, allowing visual monitoring of the fluid inside.

Common Specifications & Performance Parameters Table

The specifications of PTFE capillary tubing vary widely. Below are some common parameter ranges:

Parameter Typical Range Notes

Inner Diameter (ID) 0.1 mm ~ 2.0 mm (100 μm ~ 2000 μm) Smaller or larger IDs can be custom-made, but with varying difficulty.

Outer Diameter (OD) 0.5 mm ~ 4.0 mm The OD is determined by the ID and the wall thickness.

Wall Thickness 0.2 mm ~ 1.0 mm A thicker wall increases pressure rating but reduces flexibility.

Tolerance ±0.05 mm ~ ±0.1 mm High-precision applications require tighter tolerance products.

Operating Temperature -190°C ~ +260°C (short-term up to 300°C) Exceeds the capabilities of most elastomers and plastics.

Operating Pressure 0.1 ~ 0.5 MPa (approx. 1 ~ 5 bar) Note: PTFE is relatively soft; capillary tubing has limited pressure resistance. Do not exceed pressure ratings.

Color White (natural), Semi-translucent, Black (with carbon black) Black tubing is often used for light-sensitive or UV protection applications.

 

Primary Application Fields

1. Analytical Instrumentation & Chromatography Systems (Core Application)

   · Gas Chromatography / Liquid Chromatography (GC/HPLC): Used as connection tubing, syringe needles, and column liners. Its inert surface prevents sample adsorption and decomposition, crucial for ensuring accurate analytical results.

2. Semiconductor & Integrated Circuit (IC) Manufacturing

   · Transferring ultra-pure chemicals (e.g., etchants, developers, high-purity acids/bases), high-purity water, and specialty gases. Its high purity is key to ensuring no metallic ion contamination, directly impacting chip yield.

3. Medical Devices & Life Sciences

   · Minimally Invasive Surgical Instruments: Such as catheters and sheaths for guidewires, utilizing its flexibility and biocompatibility.

   · Laboratory Equipment: Used for cell culture, drug delivery, and fluidic channels in microfluidic chips.

   · Biopharmaceuticals: Transferring metal-ion-sensitive biologicals like proteins and vaccines.

4. Chemical & Process Industry

   · Used for micro-dosing, sampling of corrosive media, instrument impulse lines, and pneumatic signal lines.

5. Scientific Research & Experimentation

   · Serves as miniature fluid conduits or insulating sleeves requiring corrosion resistance and high temperature stability in various physics and chemistry experiments.

 

Selection Guide & Considerations

When selecting PTFE capillary tubing, refer to the table above and consider these factors:

· Size Compatibility: Precisely select the Inner Diameter and Outer Diameter based on system interfaces and flow rate requirements.

· Pressure Requirements: Always confirm the working pressure is well below the capillary tube's pressure rating. Use metal sleeves for reinforcement if necessary.

· Temperature Compatibility: While PTFE has a wide temperature range, ensure connected components can withstand the same temperatures.

· Length & Color: Choose the length as needed. Select the color based on light sensitivity requirements (e.g., black for UV protection).

· Installation & Connection: The tubing is flexible. Use specialized fittings for PTFE tubing (e.g., ferrule type, barbed type) during connection. Avoid sharp bends and kinks to prevent clogging or breakage.

 

PTFE Capillary Tubing is a high-performance material that combines exceptional chemical inertness, extreme temperature stability, high purity, and miniature precision manufacturing. Although not suitable for high-pressure applications, it is an irreplaceable choice for handling high-purity, highly corrosive, and high-temperature fluids. It acts as the essential "micro-capillary" in modern precision manufacturing and scientific research.