Nuts are only half of… Ferrule that’s doing most of the work

Ferrules aren’t nearly as complicated as their nut counterparts, but they do have some distinguishing features to help you determine which ones to use. One thing they have in common is their tapered noses…and it’s at the end of this nose where ferrules do what they were designed to do — grip the tubing wall!

When selecting the correct fitting for a given application, the following should be considered:

• tubing size
• pressure requirements
• mating nut
• receiving port geometry – most important

Watrex: Picture 1: Different between ferrule configurations.

Generally, low pressure receiving ports end in a flat-bottom configuration. The ferrules used with this type of port will typically have their tapered noses facing toward the nut and away from the flat bottom of the receiving port.

High pressure receiving ports have an internal taper just past the threaded portion of the port. Then, just beyond the internal taper is a small pocket — often called the “tubing pocket” — which is nearly the same diameter as the tubing that extends into it. In these types of ports, the tapered nose of the ferrule faces away from the nut and toward the port.

“Tapered noses face the port when pressures are high but they face the nut when low pressures apply!”

One very important characteristic of any ferrule is the material from which it is made. Ferrules are often manufactured from materials such as stainless steel, PEEK, ETFE, polypropylene and PCTFE. Materials such as PEEK polymer (a beige-colored plastic), PCTFE, and stainless steel are often used to manufacture ferrules for high pressure applications. Softer polymers, including ETFE and polypropylene, are used primarily (although not solely) in lower-pressure applications. You can find all variants in our product range.

Browse the HPLC consumables catalogs from our suppliers IDEX, VICI and Optimize Technologies and choose the best for you and your systems!

Still unsure which nut and ferrule combination to choose? Contact us at [email protected] or visit our website www.watrex.com and we will be happy to advise you!