Soft tubing can use two types of fittings, barbed fittings and compression fittings.

The Following Are The Types Of pp quick connect fitting

Barbed fittings
Barbed fittings are simple, not very expensive, very easy to use and have only one number to mark them. The one number marks the ID (Inner Diameter) of the tubing that will be compatible with the fitting itself. The meaning is that there are three main types of barbed fittings: 10mm (3/8”), 12mm (7/16”) and 13mm (1/2”). It is not necessary, but it is rather recommended to use some type of tightening system to secure the tube on the barb fitting. Meanwhile, several types of clamps are available. You can use plastic clamps, metal clamps or even just ordinary cable zip ties.

While barbed fittings are easy to use and are cheap, they are often aesthetically challenged. In more direct words, a bit ugly. But it doesn’t matter, that’s why compression fittings are there!

Compression fittings
Same as the barb fittings, compression fittings can also support various tubes. Unlike the simple barbed ones, compression fittings are marked with two numbers, and both the ID and OD markings of the tubes must match the fitting.

Thankfully, both the tubing and fitting types is standardized, so you are left to choose from the earlier mentioned 10/13, 10/16, 12/16 and 13/19 sizes.

A compression fitting consists of two parts: the main part is the base and it’s very similar to the barbed fitting, but it has a thread at the bottom. The other part is the locking ring that 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, much of the compression fitting is exposed, leaving a lot of room for manufacturers to play with the aesthetics. The locking ring can be formed and painted in many exciting ways and that is why builders are favoring them for their water cooling systems.

Compression fittings are more expensive and require a bit more access, because the user must tighten the locking ring to ensure a leak free connection. A simple fitting tightening can be a time consuming process, especially if mATX or mITX cases are used and you just can’t get a good grip on the locking ring.

For reasons like this, it is recommended to combine quality and compatibility tested tubing and fittings, because even a few microns of misalignment in the thickness of the tubing can make the tightening of the locking ring hard or even impossible.

Push-In fittings
Fittings for hard tubes come in two sizes and two types. Most common sizes are 12mm and 16mm tubes. Hard tube fittings feature only one number for labeling, which is for the OD (Outer Diameter) of the tube it can accommodate.

Fittings for hard tubing can be simple push-in (HD fitting) type. The HD fitting has two o-rings on the inside – you just have to push the tube into the fitting and airtight seal is made.
Same as for the soft tubing and other water cooling components, you cannot pick up just any random hard tubes from the flea market. The tubes you use must exactly match 12 or 16mm outer diameter (or the diameter set by the fitting you bought), because if leaks can occur, your components may be harmed. Always pick parts from well known manufacturers to avoid unpleasant experiences with water cooling.

Hard Compression fittings

We said that one type of fitting used for hard tubing is the HD – plug in type, and the other one is called HDC – Compression fittings. The HDC fitting, much like the ordinary compression fitting, consists out of two parts: the base, and the top locking ring. The story is exactly the same with compression fittings and compression fittings for hard tubing. They are safer and better looking too.

The HDC fitting has two o-rings – one in the base and one at the top that is being compressed against the tubing when the locking ring is being tightened.