PTFE Capillary Tube FAQ

PTFE capillary tubing is used when a conventional PTFE tube is too small for the application. Its small bore is useful for controlled fluid transfer, sampling, insulation, analytical equipment and compact assemblies where internal space is limited.

WITFLON currently lists PTFE capillary tubing with typical ID ranges of 0.3–5 mm and product examples including 1/32" ID × 1/16" OD, 1/16" ID × 1/8" OD, 1 mm ID × 2 mm OD, and 1.5 mm ID × 1.8 mm OD. The company also offers customized lengths and OEM/ODM production.

1. What is PTFE capillary tubing used for?

PTFE capillary tubing is a small-bore PTFE tube designed for applications where the available space is limited or where a small, controlled flow path is required.

WITFLON lists applications in:

• Medical and biotechnology
• Chemical processing
• Laboratory equipment
• Electronics and telecommunications
• Automotive
• Aerospace
• 3D printing
• Electrical insulation

For laboratory and chemical applications, the smooth PTFE bore helps reduce interaction between the tube wall and the transported medium. In medical equipment, small PTFE tubing can serve as a catheter liner, protective sheath or part of a multi-lumen structure.

PTFE capillary tubing is particularly useful when the application requires a combination of small internal diameter, chemical resistance, low friction and electrical insulation.

2. What is the smallest PTFE capillary size?

WITFLON's PTFE capillary tubing page lists a typical ID range of 0.3–5 mm. This means 0.3 mm ID is the smallest typical internal diameter currently shown in its published capillary specification range.

However, this should not be interpreted as a universal minimum for every custom project.

For very small-bore tubing, the practical minimum depends on:

• Inner diameter
• Outer diameter
• Wall thickness
• Length
• Material grade
• Required tolerance
• Tube flexibility
• Production volume

WITFLON also manufactures customized tubing based on drawings or technical specifications, so customers requiring a size outside the standard listed range can submit the required dimensions for engineering review.

Typical WITFLON examples

3. How is PTFE capillary tube tolerance controlled?

For capillary tubing, tolerance control starts with the extrusion process rather than the final inspection alone.

The key dimensions are:

• ID - Inner Diameter
• OD - Outer Diameter
• Wall Thickness
• Concentricity
• Length

A small change in ID can significantly affect a capillary's flow characteristics, while variation in OD can create problems when the tube is inserted into another component.

WITFLON's medical custom multi-lumen tubing page states that dimensional tolerances can be controlled to approximately ±0.03 mm to ±0.05 mm for specified products. The actual tolerance for PTFE capillary tubing depends on the diameter, wall thickness, structure and customer drawing.

For a precision capillary project, the customer should specify which dimensions are critical rather than simply requesting a generic "tight tolerance."

Recommended RFQ information

ID + OD + Wall Thickness + Length + Tolerance

If the tube is part of a fluid system, also provide:

Fluid + Flow Requirement + Temperature + Pressure

4. Can PTFE capillary tubing be customized?

Yes.

WITFLON provides OEM/ODM production and can manufacture tubing according to customer samples or technical drawings. Its capillary product page specifically states that samples or technical drawings can be used as the basis for production, with molds and fixtures available when required.

Customization can include:

Dimensions

• ID
• OD
• Wall thickness
• Length
• Dimensional tolerance

Material

• Virgin PTFE
• Other fluoropolymer options where appropriate

Appearance

• Natural white
• Colored tubing
• Customized appearance

Structure

• Straight bore
• Thin wall
• Special profile
• Multi-lumen

For a custom capillary tube, the fastest way to establish feasibility is to provide a 2D drawing or a physical sample.

5. What is the maximum operating temperature?

WITFLON publishes different temperature figures on different PTFE capillary product pages.

Its general PTFE capillary information gives a temperature range of approximately -65°C to +260°C, while individual capillary products state a broader material capability of approximately -65°C to +260°C. Its standard PTFE tubing pages commonly state -65°C to +260°C.

For this reason, it is better not to assign one temperature figure to every PTFE capillary tube.

The actual allowable temperature depends on:

• PTFE grade
• ID and wall thickness
• Pressure
• Continuous or intermittent heating
• Mechanical loading
• Chemical medium

For an engineering project, WITFLON should confirm the operating limit against the specific tube specification rather than using the material's maximum temperature as the working temperature.

6. Can PTFE capillary tubing handle chemicals?

Yes. Chemical resistance is one of the main reasons to select PTFE capillary tubing.

WITFLON describes PTFE capillary tubing as having excellent chemical resistance and lists applications involving acids, bases, solvents and corrosive media. The company also describes its capillary tubing as suitable for chemical processing and laboratory applications.

The PTFE bore is useful where the transported material needs to remain relatively isolated from the tubing wall.

Typical applications include:

• Chemical sampling
• Laboratory analysis
• Corrosive fluid transfer
• High-purity reagent transfer
• Pharmaceutical equipment
• Semiconductor processes

Still, chemical compatibility should be checked against the actual chemical, concentration, temperature and exposure time. "Chemical resistant" should not be treated as a blanket approval for every chemical under every condition.

7. What lengths are available?

WITFLON supplies PTFE capillary tubing in different lengths depending on the product and application.

For example, its 1 mm ID × 2 mm OD flexible PTFE clear tubing is listed at 305 meters per spool or customized. Other products have different package lengths, and WITFLON states that production time and supply arrangements depend on the order quantity and specification.

Custom lengths can be requested for:

• Laboratory assemblies
• Medical components
• Electrical insulation
• Equipment tubing
• OEM production
• Cut-to-length kits
• For a quotation, specify:

Required length per piece + total quantity + packaging method

For example:

500 mm/pcs × 10,000 pcs

is more useful for production planning than simply stating "10,000 pieces."

8. Can you provide samples?

Yes.

WITFLON states that sample orders are available, and its capillary tubing page also provides an OEM/ODM sample service. The company says it can manufacture according to customer samples or technical drawings and can build molds and fixtures when necessary.

For medical tubing, WITFLON's published product information also states that sample availability is supported, with sample time commonly listed as 1–2 days for the relevant medical tubing category.

For a custom PTFE capillary sample, provide:

• ID
• OD
• Wall thickness
• Length
• Material
• Color
• Tolerance
• Application
• Temperature
• Pressure
• Fluid
• Drawing, if available
• Required sample quantity

If you do not have a drawing, a physical sample can also be used as the starting point. WITFLON's published capillary FAQ specifically confirms production based on customer samples or technical drawings.

Before requesting a quotation, prepare these specifications:

WITFLON's published production capabilities include more than 150 extrusion production lines, 12 medical-grade pipe production machines, and dedicated cleanroom facilities. Its factory information also states that the company supports both standard and custom production, which is relevant when a capillary tube falls outside a conventional catalogue size.

Request a PTFE Capillary Tube Sample

For a standard size, provide the ID × OD, length and quantity.

For a custom capillary tube, send the drawing or sample together with the required material, tolerance and application conditions. WITFLON can review the specification, confirm production feasibility and arrange sample production before a larger OEM order