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The numbers assigned equate to the O.D. (outside diameters) of the tubing in 1/16". Since tubing and hoses are to be found with assorted wall thicknesses, we can now understand that the designated size number does not necessarily tell you how large the inside diameter will be. (For example, the inside diameter of an Earl’s size 6 hose end is nearly as large as the inside diameter of some other manufacturers’-8 hose ends.
Each AN size number has its own standard thread size, which can be seen in column three of the chart. Again, these are the same thread sizes that have been used in aircraft and industrial applications for many years.
(The chart to the right will clarify this point).
|
|
AN Size
|
Metal Tube O.D.
|
Thread size
|
|
2
|
1/8
|
5/16-24 SAE
|
|
3
|
3/16
|
3/8-24 SAE
|
|
4
|
1/4
|
7/16–20 SAE
|
|
5
|
5/16
|
1/2-20 SAE
|
|
6
|
3/8
|
9/16-18 SAE
|
|
8
|
1/2
|
3/4-16 SAE
|
|
10
|
5/8
|
7/8-14 SAE
|
|
12
|
3/4
|
1-1/16-12 SAE
|
|
16
|
1
|
1-5/16-12 SAE
|
|
20
|
1-1/4
|
1/5/8-12 SAE
|
|
24
|
1-1/2
|
1-7/8-12 SAE
|
|
28
|
1-3/4
|
2-1/4-12 SAE
|
|
32
|
2
|
2-1/2-12 SAE
|
|