Often used on instruments, and some air and hydraulic lines, compression fittings are used on a variety of tubing materials; however, they should never be used on brakes.
Hydraulic brake-fitting adapters can be used to connect brake lines to different size ports in a dual master cylinder, combine different types of fitting-such as inverted flare, pipe and AN-or to mix standard and metric fittings.
Conventional automotive lines and fittings use 45-degree double flares; AN lines and fittings use 37-degree single flares. The reference "AN" stands for Army/Navy and it was a system devised by the government to ensure interchangeability and compatibility of parts made by various manufacturers. With the AN system, a dash number is assigned to each different size metal tubing and the corresponding fittings, and the same numbers are also assigned to the hose and their ends. Another application of 37-degree flares will be found on JIC hydraulic fittings.
AN fittings are often found on street rods in combination with pipe and inverted flare fittings, which means special adapters are required. Suppliers, such as Pure Choice Motorsports, can supply such fittings as well as lines, individual parts, or complete kits.
Look long and hard enough and you're likely to find an adapter to connect just about any two fittings together. However, keep in mind that when it comes to brakes, only 45-degree double-flare or 37-degree AN components should be used.
Clamp-style Hose Fittings
Clamp-style hose fittings are manufactured for low-pressure applications with multipurpose hose (worm-style clamps are good for a maximum of 35 psi). A hose clamp is required between the raised end of the fitting and the end of the hose.
Push-On Hose Fittings
Push-on hose fittings are manufactured for low and medium pressure (maximum pressure 200 to 250 psi). These fittings are quick connecting and have high resistance to vibration damage. When used in combination with the proper hose, no clamps are required.
In most cases, properly flared and installed fittings should seal by themselves, however, Teflon tape or Teflon-based sealing compound is often used on pipe threads.
Teflon tape can prevent leaks and make it easier to tighten fittings and disassemble them later, and it can reduce/eliminate thread galling and protect fasteners made from corrosion. However, there are some places it should never be used, such as the engine's electrical senders and the cooler line fittings in automatic transmissions.
Used on senders, it will insulate them, preventing the proper grounding necessary for accurate gauge operation. On transmission lines, it can make the pipe fittings tighten so easily that the tapered threads can split the case.
So Many Choices
If we included every fitting available in the form of tubing and fitting, we wouldn't have room for anything else in the magazine this month, so we've tried to cover the most common items a home builder will come across. Next time we'll show how to properly flare tubing, use sealants, and build solid and rigid lines, and a bunch more.
Another common junction is the inverted flare branch tee. It has two inverted flare connec
A simple pipe nipple uses male threads on both ends.
This is a properly done 37-degree AN flare. Notice the sleeve that is used.
SAE 45-degree fittings use a single flare. This cutaway drawing shows how they seal.
The complete AN connection consists of the flared line, sleeve, and nut.
AN fittings are sized by "dash" numbers. Each number refers to 1/16-inch. As an example, -
A common combination: -6 AN loine and a -6 to 1/4-inch pipe adapter.
What we have here is an -8 AN (1/2-inch) to 1/2-inch tube compression fitting. Note the sl
Compression fitting such as this one will only go together properly one way. Note how the