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How to Assemble PTFE Hose End Fittings

PTFE hose ends are quite a bit different from regular swivel hose ends intended for braided rubber hose. PTFE hose is closer in design to a “flexible tube” than a rubber hose, and the hose ends seal using a ferrule (sometimes called an olive) rather than sealing by sandwiching the rubber between the hose end body and collar. It’s important to make sure you follow the proper procedures to ensure correct assembly, reliability, and performance. Remember, hoses fittings aren’t just for looks or for delivering fluids, they are safety items designed to ensure that the fluids they are carrying get to where they need to go without leaking. Failure properly assemble these parts can lead to poor performance or leaking flammable fluids, and we all know that’s not good!

Step 1: Cut the hose to desired length.
Measure twice and make sure the hose is the length necessary to go from Point A to Point B. If necessary you can try cutting it a bit longer than you actually need to, then shortening it up a bit until the length is just right for your application. It’s important to ensure you get a clean perpendicular cut on the hose, as deviations can cause the hose to not seal properly inside the hose end, leading to leaks. In fact, on PTFE hose ends, any significant deviation from 90 degrees means you won’t be able to get the ferrule on the hose at all.

Note: Cutting the hose requires special tools. We don’t recommend using metal cut-off wheels or abrasive cutting tools as these can cause a large amount of dust to build up in the hose which must be cleaned prior to continuing the assembly process. Failure to clean can result in the dust entering your parts, causing damage. We recommend using either a hydraulic hose cutting blade or a 350 MCM electrical cable cutter.

Step 2: Place the collar on the hose
This is an extremely important step that is very easy to forget. Many will begin attempting to get the ferrule onto the hose, then realize that they cannot get the collar on because the overall width of the hose at the tip has increased. The collar is sized perfectly for the hose you have, so if you do this then you will need to cut the hose back to an untouched area (typically about 1 inch back) in order to perform this step.

Actually performing this step is very easy, simply slide the narrow part (opening without the threads) onto the hose.

Step 3: Place the Ferrule on the tip of the hose
Begin by first making sure the hose is perfectly round. The ferrule is machined very precisely and the inside of the barrel matches very closely to the outside of the PTFE inner liner, and significant deviation from a circle means that you won’t be able to get this part on. You can use the hose end body as a tool to re-shape the inner liner and get it in shape. Sometimes the braiding can interfere with the placing of the ferrule, if that is the case then use a small flathead screwdriver or similar device to gently separate the braiding, taking care to avoid piercing the liner.

Please be aware that ANY significant fraying of the outer braid can cause it to get caught in the threads during assembly in a future step, so be sure to use a pair of scissors to trim any fraying to prevent damage during assembly.

Step 4: Lubricate the hose end body
Apply a small amount of oil to a rag and use the rag to apply the oil to the hose end body. Only a thin layer is necessary. Do not use anti-seize or grease. Be sure to cover the threads, nipple, and if desired, lubricate the threads on the socket. Only a small amount of oil is necessary to help the parts slide. Don’t go nuts.

Step 5: Assemble!
Now you can begin assembly of the hose end. First bring the collar up to the tip of the hose and insert the hose end body’s barb into the hose-ferrule assembly. Bring the collar and hose end body together and begin threading by hand. If you are not able to do this, there may be fraying or something interfering with the engagement. Remember, if you feel ANY kind of binding then stop immediately. These parts are made of aluminum and are very soft, if there is binding then this means that there is a flaw in the machining or you are cross-threading the parts. They are machined very precisely and if it doesn’t go together smoothly then something is wrong.

You should be able to get the hose end body to within about 1/16″ (1-2mm) of the socket. This is best to ensure a proper seal and to make sure it looks good.

Step 6: Clean and Test
Clean the hose and hose end with a solvent to remove any excess oil or residue, then immediately pressure test the completed assembly. If you encounter any leaks, determine the reason why and take steps from there to resolve the leaks. If you do not have access to a pressure tester, then when the hose assembly is installed in the vehicle then ALWAYS make sure you observe for any leaks or issues before putting the vehicle into service.

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