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What are AN fittings used for?  assembly guide

What are AN fittings used for? assembly guide

Posted by Matthew Marks on 10th Apr 2021

Welcome back to our blog! Today is a bit more of an informational blog on AN hose and fittings as we get asked more and more about each situation's differences and advantages. These hoses and fittings are perfect for custom lines or to replace the stock OEM perished lines.

You can use AN style line for nearly every fluid transfer application, so water, oil, coolant and are not just limited to cars. We have had many customers using them in planes, motorbikes, and other applications.

There are a few different types of AN hose and fittings, but we will cover the main ones as if you were building a fuel system or oil lines.

The Differences

Nitrile Rubber

So, starting with the hardest to assemble, the first two hoses that people use are nitrile rubber or PTFE hoses. Firstly, the nitrile rubber hoses are universal and can be used with most pump fuels and oil and offer the most considerable bend radius of the two. Sometimes this will be important depending on how tight the bends are you need in your oil, water or fuel system.

The nitrile rubber line will need to be fitted with conventional swivel hose end fittings, so you CANNOT use PTFE fittings on a nitrile rubber hose, as they will not work.

Another thing to note with nitrile rubber hose is that you CANNOT use them inside the car as fuel vapour can seep from the hose into the vehicle, which you do not want!


Moving on to PTFE, you can also use them with all pump fuels, water, and oils. Still, the main advantage is that they are rated for higher ethanol content than rubber, so if you are building a race fuel system that uses a higher ethanol content such as e85 or any other race fuel, you will need to use PTFE not degrade the AN line.

You can also use PTFE lines inside a car as you will not get any fuel vapour seeping from the lines, as seen in our fuel system install video a few weeks back.

Rubber hoses, as mentioned earlier, are much more flexible than the PTFE hose, so you need to consider this when choosing between the two. Two other advantages of the PTFE hose on top of using higher ethanol rated fuels is that the line is lighter than nitrile rubber.

When using PTFE hose, you will NEED to use PTFE fittings also, as, inside the hose fitting, they have a crushed olive which seals the fittings to ensure they will not leak.

We get asked quite often about the differences between the fittings, but all you need to know is that you can only use Standard swivel hose ends on nitrile rubber lines and PTFE fittings on the PTFE line.

The next option you can choose from is a stainless-steel outer braid or nylon braid. The stainless is more robust, a twin stainless weave, whereas the nylon has a single layer of stainless steel for the inside braid and a nylon braid for the outer.

The nylon is also slightly more flexible, so you will need to bear that in mind when choosing between the two. The last difference is aesthetics, so it boils down to whether you prefer silver or black lines!

The stainless and nylon braided lines need to be cut with something such as a disk cutter, where we always recommend using a 1mm cutting disc, placing the hose in a vice, and using masking tape or similar to keep the braid from fraying whilst cutting.


The third hose we want to talk about is the push lock hose, the easiest to install of the three types. This hose is also safe to use with oil, water, and fuel and does not require anything special to cut it, just standard hose cutters.

Again, with the push-lock hose, you will need to use PUSHLOCK hose fittings that can be secured with a jubilee clip. Two things to note is that you cannot use a push-lock hose for E85 or anything higher ethanol-based than pump fuel, and it also does not have the same abrasion resistance as the braided hose.


So, we have been over which fittings are used for each hose application; we will install the fittings with the hose. They are all slightly different, so we will go over each one, starting with the easiest, the push lock hose.

So cutting is straightforward using any cutter type as the hose is flexible and only made from polyethene. All you need to do is measure when you need to cut it and push the fittings to put a jubilee in first if you are using those to secure it.

Make sure the hose is far enough down to reach the collar and tighten the hose. It is as easy as that!

Moving onto PTFE, you firstly want to cut the hose using a 1mm cutting disc where you will measure the hose to the correct length for your application and put a masking tape marker to know where to cut.

You will want to hold the hose in a vice for this step, so the cut is as straight as possible and does not affect the braid. Once this is cut, you will want to assemble the line. For this, you will want to remove the hose end and the olive from the centre and push the end connector over the hose for later.

Next, insert the olive inside the line and push down until the PTFE reaches the lip on the olive. Next, attach the male part of the hose inside the PTFE and push as far as it will go. Then pull the female part of the hose you moved over at the beginning and tighten it until it does not go anymore. You have just made your first PTFE AN line! Again, if you need to see a visual guide, please click here to head to our YouTube video.

Next up is the Rubber hose fitting installation, which is a little bit harder, and more accessible for issues to occur, in our opinion. Firstly, you will want to repeat the same step to cut the hose as the PTFE and once finished, get the hose ready to assemble your AN fitting.

For this step, we find it easiest to push a small amount of oil or WD40 inside the hose to make the fitting bottom out easier. Here it differs from making PTFE hoses. The hose ends for the rubber line do not push fully over the hose but will push in until it seals against the lip inside the fitting.

Now you will want to attach the hose end in the vice (vice jaws help not to damage the fittings) and keep screwing the fitting in until it reaches the bottom, and you are done. If you struggled to put any lines together in the guide, please refer to our YouTube video, where we do a complete start to finish.

The main difference between the two is that the rubber hose fittings need to fully bottom out against each other to seal, whereas the PTFE fittings use the crushed olive to seal, so they will often not touch each other at the bottom of the hose.

So that is it for our hose differences and fitting guide! Hopefully, you guys found this helpful and are well on your way to making your fittings. Let us know in the comments what you thought of this blog and which other subjects you would like to see in the future.