Originally Posted by http://en.wikipedia.org
The AN thread is a particular type of fitting used to connect flexible hoses and rigid metal tubing that carry fluid. It is a US military-derived specification stemming from a joint standard agreed upon by the Army and Navy, hence AN. However, some documents say the name is really Air Force/Navy.
AN sizes range from -2 (dash two) to -32 in irregular steps, with each step equating to the OD (outside diameter) of the tubing in 1/16" increments. Therefore, a -8 AN size would be equal to 1/2" OD tube (8 x 1/16 = 1/2). However, this system does not specify the ID (inside diameter) of the tubing because the tube wall can vary in thickness. Each AN size also uses its own standard thread size.
AN fittings are a flare fitting, using 37° flared tubing to form a metal-metal seal. They are similar to other 37° flared fittings, such as JIC fittings, which is their industrial variant. The two are interchangeable in theory, though this is typically not recommended due to the exacting specifications and demands of the aerospace industry. The differences between them relate to thread class (how tight a fit the threads are) and the metals used.
and here's my input.
The "-" in front of the AN fitting is called a "dash" not a negative. If you saw "AN -4" or "-4 AN" you would pronounce A N dash four.
The number after the AN, refer to the size of hose it connects to in 16th's (x/16):
1/8" hose would be 2/16" = DASH 2 OR -2AN
3/16" hose would be 3/16" = DASH 3 OR -3AN
4/16" hose would be 1/4" = DASH 4 OR -4AN
5/16" hose would be 5/16" = DASH 5 OR -5AN
6/16" hose would be 3/8" = DASH 6 OR -6AN
8/16" hose would be 1/2" = DASH 8 OR -8AN
Note that after -6AN, the fittings are of even numbers. -2, -3 & -5 are metric USA conversions.
Moving on for now:
There are 4 types of hoses COMMONLY used in the racing (AN fitting) industry today:
-Rubber with Stainless Steel shell (see pic below)
-Teflon with Stainless steel shell (see pic below)
There are 3 types of hose ends (fittings) COMMONLY used in the racing (AN fitting) industry today:
The push lock and threaded types can be found here http://www.goodridge.net/usa/pdf/mot...llation_ms.pdf)
Also, I will just go over these:
BSP & NPT
These are typically tapered pipe threads found on turbo charger feeds, oil pressure sending units, and other areas under high pressure.
BSP = British Standard Pipe or metric pipe thread.
NPT = National Pipe Thread or standard pipe thread.
Im sure there's plenty more to add, but this will give all of us a good start for an FAQ on hoses.
Aircraft mechanic here so if anyone needs ideas or instrustions on assembly or plumbing of lines feel free to ask.
and your correct the dash number indicates the size of the line in 16ths a -16 would be a 1 inch line for instants.
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