Fuel Line Instruction - Hold The LIne

Building AN Hoses And Flaring Hardlines Isn't Withcraft, It Just Takes The Right Tools And A Little Practice

Tony Huntimer Mar 3, 2009 0 Comment(s)
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1. The most important thing to know about adapting a hardline to aircraft style AN fittings is that AN fittings have a 37-degree flare seat. Your flaring tool for brake lines and household appliance lines flares tubing to 45 degrees. Here you can see the slight difference between the AN fitting (in the foreground) and a brass natural gas fitting (in the background). It doesn’t look like much of a difference, but the 8-degree difference is enough to produce a potentially dangerous leak, especially if you are working with fuel lines.

2. Build a small test project before actually bending your fuel lines. This will get you familiar with flaring and bending before wasting some valuable time and materials. Start off with about a 12-inch test piece. The best way to ensure a straight cut is to use a tubing cutter. Tighten the blade a little bit at a time and roll it around the tubing after each adjustment.

4.The aluminum tubing is extremely soft, so when you’re done cutting it the opening will be considerably smaller. Use a deburring tool to clean up the burr inside the end of the tubing.

5.There are a few different types of tubing benders on the market. This design is the easiest to use and can be found at most hardware stores.

6.This is a coil spring-type bender. It works good except it does not do as clean of a job as the lever-type bender and will not bend a very tight radius. It slides over the tubing and the coil helps keep the tubing from kinking.

7.Don’t forget to put the tube nut and sleeve on the tubing in the correct direction. Double-check them before flaring the end. If you get one backwards, you’re going to have a nice piece of scrap.

8.These instructions are for using a Ridgid Tools ratcheting flaring tool model number 377. Slip the tubing about 1/8-inch below the top surface of the flaring bar. If the tubing is too high, the flare will be too big for the tube nut to slip over. Slide the yoke over the center of the tubing to be flared. Turn the handle until it starts ratcheting and your flare is done.

9.Loosen the yoke and remove your flare from the flaring bar. Slide the tube sleeve and nut into place. If the tube nut doesn’t fit over the flare, your tubing was sticking up too far in the flaring bar. Cut it off and try again.

10.Now you’re ready to attach an AN fitting to your project. You can do so by using a male flare union (top) or you can assemble your braided hose with a hose end with a male flare (bottom).

11.You can also use a bulkhead male flare union to mount the line to a bracket or through a panel. Slip the union through the hole and thread on the nut for a rigid mount.

12.Here’s a cutaway view of an XRP fitting that shows all the features of their hose end, including exclusive patented features.  Unlike some competitors’ product, XRP fittings are hard anodized which prevents galling of the threads and helps protect the finish from tool marks and fading due to direct sunlight. (Illustration courtesy of XRP)

13.Wrap the hose with duct tape and cut the center of the tape. This helps reduce the amount of braid that frays during the process.




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