I see that all braided steel fuel/oil/hydraulic/brake line is sold with a formulation like -6 AN. Why the minus sign, to what does the number refer, and what is "AN"? Thanks, Untame
The -number refers to number of 16ths of an inch of the I.D. of the hose. -6 = 6 x 16ths = 3/8 -10 = 10 x 16ths = 5/8 and so on. AN refers to the type of fitting it will attach to. At least thats what I've been told
Thanks for clarifying the numbers. Seems like a goofy way to measure it. It should be just "3/8" not -6AN.
AN is Army-Navy. The fittings were originally used in military applications. The 1/16 th thing is just another form of measurement. Lotsa things use their own nomenclature. For instance, fluorescent bulbs are measured in eighths... T-8 bulbs are 1 inch in diameter, T-5 bulbs are five eighths of an inch in dia. Everyone likes their own system... That way they can throw around terms that make the layman think they're smarter than they are. Nowhere is this more prevalent than in education and medical circles.
Almost everything uses the AN system and includes everything from the ring you wear on finger to hose clamps and of course hose. It gets a little confusing when you need a hose clamp as a 2" inside hose needs a #32 clamp (and most quality clamps are stamped with this number) because the OD of the hose is closer to 2 1/4". And Braided steel hose is similar in that a #8 does not measure exactly 1/2", it to has it's own system but the idea is similar for most automotive products.
The AN style fittings and lines were originally designed for the B-29, I believe, due to the size of the aircraft and flight controls, the existing 1k psi hydraulic systems would have been mushy and unresponsive during flight. The 3k psi system was designed to allow for faster response and smaller, lighter hydraulic controls. The AN system uses a 37 degree flare, whereas the legacy 1k systems used a 45 degree double flare. The AN system made necessary a military standard part numbering system to standardize the installation and make field repair quick and inexpensive. If the field maintained needed a nut for a 3/8" bulkhead fitting, that fella would reach for a AN924-6 nut. Different fittings have different basic numbers, and the number after the dash designates the size in 1/16's of an inch.
The AN fittings are easier to work with and seal tight with minium wrench torque, and you can use them over and over without worring about cross threading.
I developed system of measurement - similar to what the Greeks developed in ancient times. Only mine is based on beer cans, and applies to everything; time, volume and distance
LOL!!! I haven't heard this in years!! Back in the 80's when I first came on the job, one of my old Sergeants used to measure all his off-duty jobs that way. Seal the driveway, that was a 2 sixpack job. Do a tune-up on the car, that was a 1 sixpack job. Scariest thing was, he was our senior bomb tech .
Actually, this is a generally true statement when referring to braided hose. However, there are exceptions and the teflon hose that uses AN fittings is one of those exceptions. The i.d. of Aeroquip 2807-6, for example is not .375", it's .32. -8 is not .500, it's .42. If you needed 1/2" i.d., you'd have to go to -10. Here's a reference. http://www.aeroquip.cc/fbc03002807-03aeroquiphosestainlesssteelteflon2807-3.aspx Standard hydraulic hose does follow the 16ths rule exactly.
Now you can see why the metric system never really worked here, and does not really work overseas either. The purpose of an item trumps a logical system that attempts to make logical conformity. Really great answers by the way, I miss all that technical stuff.
If you look at AN hard lines they are tubing. And tubing is measured by it's OD. Pipe is measured by it's ID. That's why 1/2 NPT is so much larger than 1/2 inch. So a -6 (dash 6 not minus) AN tube has a 3/8OD same as your brake lines. The braided stainless and other AN hose has an ID roughly equivalent to a -6 hard line which has a 3/6 OD.
If you go to a hydraulic shop that doesn't recognize AN as being a proper term, they understand JIC. What JIC stands for doesn't matter to me as long as it works.
JIC is Joint Industry Conference. A JIC fitting will interchange with an AN fitting but is 40% weaker than the AN. It is an "industrial" version not rated for flight.
Here is a chart, JC AN (Army-Navy) Fitting Thread Size Chart <CENTER><TABLE border=1 cellSpacing=0 borderColor=#000000 width=400 bgColor=#ffff00><TBODY><TR><TD width="25%">AN Size </TD><TD width="25%">Hose Size </TD><TD width="25%">Thread Size </TD></TR><TR><TD width="25%" align=middle>-3</TD><TD width="25%" align=middle>3/16</TD><TD width="25%" align=middle>3/8-24 SAE</TD></TR><TR><TD width="25%" align=middle>-4</TD><TD width="25%" align=middle>1/4</TD><TD width="25%" align=middle>7/16-20 SAE</TD></TR><TR><TD width="25%" align=middle>-6</TD><TD width="25%" align=middle>3/8</TD><TD width="25%" align=middle>9/16-18 SAE</TD></TR><TR><TD width="25%" align=middle>-8</TD><TD width="25%" align=middle>1/2</TD><TD width="25%" align=middle>3/4-16 SAE</TD></TR><TR><TD width="25%" align=middle>-10</TD><TD width="25%" align=middle>5/8</TD><TD width="25%" align=middle>7/8-14 SAE</TD></TR><TR><TD width="25%" align=middle>-12</TD><TD width="25%" align=middle>3/4</TD><TD width="25%" align=middle>1-1/16 SAE</TD></TR><TR><TD width="25%" align=middle>-16</TD><TD width="25%" align=middle>1</TD><TD width="25%" align=middle>1-5/16 SAE</TD></TR><TR><TD width="25%" align=middle>-20</TD><TD width="25%" align=middle>1-1/4</TD><TD width="25%" align=middle>1-5/8 SAE</TD></TR></TBODY></TABLE></CENTER>
Correct ie: Man that's thats a big job, maybe 5 cases, 1/2 days work. We put a roof on a friends garage, big job, 2 half barrels, 1-1/2 days work. There is a definate relationship between the amount of beer and the time to do the job, haven't figured out why yet ? And we don't drink before noon but we only usually get started about 11:00 or 11:30 unless we have to get someone out of jail then we start later.
Weaker in what respect? I've got construction equipment that uses JIC fittings on hydraulic systems that run up to 6000 PSI. No problems. Bob
It's very hard to believe that a steel JIC fitting is weaker than an otherwise simular aluminum AN fitting. And remember, if I had ever put the stuff sold by Earls on an aircraft I could have lost my license.
I don't know about JICs being weaker...never heard that. They are produced to wider tolerances than are permitted to true AN fittings; my understanding is that this is mostly in the thread class of fit. A lot of the so-called "AN" fittings out there for automotive use shouldn't be allowed even on the same street as an airport......which isn't to say that they won't work OK for cars. Back in the late '70s/early '80s, there were only three brands of fittings commonly available- Russell, which IMHO had issues (though their magazine ads often had ladies with impressive talents); Earl's, which were easy to get at any speed shop & had a wide selection; & Aeroquip, which had no "racing" marketing and were only available from hose specialists, but were the best, again IMHO. Earl kind of ruled by default, but there's lots of choices now, including Chinese-made.
AN, NAS, and MS are all aircraft hardware manufacturing standards acceptable for use on type certificated aircraft. For a manufacturer to identify his hardware as AN, NAS or MS, the facility has to produce that hardware in accordance with the established standard. Even though Earls and Russell fittings LOOK like AN hardware, they are not producing to the AN standard and can not be used on certificated aircraft. For more information on AN hardware, contact Aircraft Spruce, they got one hellufa catalog of cool aircraft parts, including AN, NAS, MS hardware with great explanations of the sizing, and I think the catalog is free.
The strength increase in AN fittings is primarily thread fatigue strength due to the J threadform which produces a more rounded root radius and increased tensile stress area. see http://www.mechanicsupport.com/articleStronger.html for a more thorough explanation.
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