"AN" (Army-Navy) Sizes were established by the Aerospace industry years ago and were designated O.D. of the rigid metal tube that each size fitting is used with.
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"AN" SIZES
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
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"NPT" THREAD SIZES: Some of the most popular adapter fittings shown in our on-line shop are AN to NPT adapters
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"NPT" SIZES
While many variations are offered, column four in the chart shows which AN size corresponds to each NPT size when inside diameters (flow dimensions) are considered.
All Earl’s SWIVEL-SEALTM hose ends are designed to provide little or no restrictions when used with the corresponding AN fitting size.
We also offer a number of Metric and British Standard Pipe threads to AN fitting adapters.
We carry the largest stock levels in the industry. For Defense Department Overnights & A.O.G. Orders, they are usually serviced same day with some exceptions. Cut off times are approximate for all types of orders, please read our shipping policies for processing guidelines.