Water cooling components like fittings and tubing are best not bought from the flea market. The tubes you use must exactly match the ID and OD parameters of the fitting you are using, because if leaks occur, your components may be harmed. While in the early days we had simple barb fittings, nowadays the market has narrowed down to only compression type fittings.

While barb fittings are still available for workstation purposes and applications where the aesthetics are not a key point, the market is dominated by compression type fittings. The compression fittings themselves are divide into two major categories which are, Soft Tubing Compression and Hard Tubing Compression fittings, or for short STC and HDC. These compression fittings are marked with two numbers that state the inner diameter (ID) and outer diameter (OD) of the tubing that is compatible with the fitting. Both these number markings of the tubing must match with the fitting.

As for the old-school barb fittings, there is only one number present, the OD of the barb, which has to match with the ID of the tubing that will be used. Thankfully, both the tubing and fitting types are standardized, so you are able to choose from 10/13, 10/16, and 12/16 sizes of soft tubing compression fittings.Ī soft tubing compression fitting ( STC) consists of two parts, the main part is the base and it’s very similar to the standard barb fitting, but it has an additional thread. The other part is the locking ring which screws on to the base of the fitting and it prevents the tubing from slipping off the barb. There is a point where the locking ring compresses and grips the tube, making an airtight seal, hence the name „compression fitting“. Unlike the barbed fitting, where the tube just goes over it, the locking ring big and visible part of the compression fitting, leaving a lot of room for manufacturers to play around with the aesthetics.

Tube bending instructions chart