LC Tubing - How to set bend radius

Gust Author – Genevieve Hodson – Senior Technical Specialist

Liquid chromatography (LC) tubing can be made from a few different types of materials depending on the needs of the laboratory. The most commonly used materials for LC tubing include PEEK, Stainless Steel, PEEKsil, and PEEK-Lined Stainless Steel.

Each tubing material has fluid and sample performance differences as well as specific flexibility that is inherent to the material. If bent too tight or too often, the tubing can become thin, brittle, and weak resulting in a leak. A leaking connection would be detrimental to chromatographic results and must be replaced.

To avoid creating a break in the tubing, it is important to keep the bend of the tubing above the bend radius specific to the tubing’s material. To help visualize what is meant by ”bend radius,” a picture of a typical LC setup is presented below. A yellow circle has been drawn to illustrate a critical bend in the LC tubing.

Visualization of bend radius of a typical LC tubing setup

The circle’s radius is the line in yellow labeled ‘r’ and is the variable that changes due to the material of the tubing. Two red circles have been drawn to illustrate examples of questionable bend radiuses. These look to be too tight depending on the tubing’s material and should be measured to confirm the bend is not below the allowable specification.

Phenomenex SecurityLINK™ zero-dead volume fingertight connections come in three different types of tubing material: PEEKsil, PEEK-Lined Stainless Steel, and Stainless Steel. Table 1 is a summary of each tubing type with the specific bend radius listed.

Table 1.

Summary of each LC tubing type with specific bend radius listed

The bend radius of PEEKsil is observed to be higher at 1.00”, compared to a radius of 0.25” for the other two materials. PEEKsil tubing is made up of a PEEK outer tube lined with an inner material made of glass. Due to the inner glass layer, the tubing cannot be bent as much as Stainless Steel or PEEK-Lined Stainless Steel.

Since leaking can occur if the bend in the tubing is too tight, troubleshooting should include measuring the bend radius of the bend along with the leaking tubing. If the bend is noticed to be below the tubing’s bend radius threshold, then there are two potential solutions. For the first, a different tubing material should be chosen to allow for a smaller or tighter bend radius.

The second would be to choose a longer length of the same tubing material, allowing for a larger bend radius to be used. The second option depends on having the room available within the LC to accommodate the extra length of tubing.

To learn more about SecurityLINK and best practices for care and use when selecting your tubing visit www.phenomenex.com/SecurityLINK and for a more detailed look at Tips for Care and Use for your LC tubing, click the image below.


If you have any questions regarding your LC tubings and fittings or selecting which guard column is right for you, connect with our team of Technical Specialists through Chat Now. Visit www.phenomenex.com/chat today for quick and accurate insights and answers.

chat now about the science of champagne

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.