AN-fittings measurement - A guide to the right size
Dimensions of AN fittings, hose and pipes are some of the most common questions and misconceptions that exist about the AN system. AN is measured in inches where AN1 in theory is 1/16", AN8 is then 1/2" and AN16 is thus 1". AN8 is not 10 or 8mm which is a common misconception. How to measure is also a common misunderstanding when there are different types of AN fittings, hose, pipes and key grips. And you get different values for all of these measurements. To make it clear, we have divided the information into different categories:
- AN-fitting measurements
- AN-hose measurements
- AN-pipe / tube measurements
- AN-key grip measurements
Do you measure outer diameter or inner diameter? Thread inside or outside diameter? We'll cover how to do this right here!
AN fittings are an abbreviation of Army-Navy and came during the Second World War when lighter and better tolerance fittings than ordinary hydraulic once was needed. AN fittings have become a kind of standard in the aftermarket, performance and hobby aviation.
1. AN-fitting measurements
AN fittings are simply explained as a JIC fitting in aluminum with higher tolerances. AN fitting size is measured over the thread.
AN-fitting male (outer diameter)
Below, the thread is presented in inches / metric dimensions in the thread / metric outer diameter.
AN4 = 7/16" -20 = ~9,1mm in threads = ~11,8mm OD
AN6 = 9/16" -18 = ~11,6mm in threads = ~14,2mm OD
AN8 = 3/4" -16 = ~16,6mm in threads = ~ 19,0mm OD
AN10 = 7/8" -14 = ~19,5mm in threads = ~22,3mm OD
AN12 = 1-1/16" -12 = ~23,8mm in threads = ~26,9mm OD
AN16 = 1-5/16" -12 = ~30,2mm in threads = ~33,3mm OD
AN20 = 1-5/8" -12 = ~38,2mm n threads = ~41,4mm OD
AN-fitting female (inside diameter)
Here, the thread is presented in inches / metric inner diameter.
AN4 = 7/16" -20 = ~9,9mm ID
AN6 = 9/16" -18 = ~12,9mm ID
AN8 = 3/4" -16 = ~17,5mm ID
AN10 = 7/8" -14 = ~20,6mm ID
AN12 = 1-1/16" -12 = ~24,9mm ID
AN16 = 1-5/16" -12 = ~31,2mm ID
AN20 = 1-5/8" -12 = ~39,1mm ID
AN-hose end inner diameter
An approximate internal dimension of AN hose ends is presented here. Note that the internal dimensions of hose ends and fittings may differ depending on the type, material manufacturer, etc. Therefore, these internal measurements should only be used as guidelines.
AN4 = ~3,7mm
AN6 = ~6,0mm
AN8 = ~8,6mm
AN10 = ~11,1mm
AN12 = ~14,3mm
AN16 = ~19mm
AN20 = ~25mm
Corresponding AN adapters generally have a 1 mm larger inner diameter. Should an adapter be reduced to a smaller thread, the inner diameter will also shrink.
2. AN-hose measurements
AN hose size is measured inside the hose = (inner diameter of the hose). Depending on hose type, the outer diameter of the hose will vary. The type of hose technology has also changed since the Second World War when these connections came so the actual dimensions of the AN hose can vary. It also differs between manufacturers sometimes. So be sure to use the right hose for your AN hose ends and AN-system!
Braided rubber hose measurement (-1950)
AN3 = 3/16" hose id = ~4,76mm
AN4 = 1/4" hose id = ~6,35mm
AN5 = 5/16" hose id = ~7,9mm
AN6 = 3/8" hose id = ~9,5mm
AN8 = 1/2" hose id = ~12,7mm
AN10 = 5/8" hose id = ~15,9mm
AN12 = 3/4" hose id = ~19,05mm
AN16 = 1" hose id = ~25,4mm
AN20 = 1-1/4" hose id = ~31,75mm
Braided rubber hose measurement (nowdays)
AN4 = 7/32" ~5,4mm
AN5 = 5/16" ~7,9mm
AN6 = 11/32 ~8,7mm
AN8 = 7/16" ~11,1mm
AN10 = 9/16" ~14,2mm
AN12 = 11/16" ~17,4mm
AN16 = 7/8" ~22,2mm
AN20 = 1-1/8" ~28,5mm
Braided PTFE hose measurement (nowdays)
AN4 = 3/16" ~4,8mm
AN6 = 21/64" ~8,1mm
AN8 = 27/64" ~10,7mm
AN10 = 33/64" ~13,0mm
AN12 = 41/64" ~16,3mm
AN16 = 7/8" ~22,2mm
3. AN-pipe / tube measurements
AN pipe size is measured on the pipe outer diameter. The thickness varies between manufacturers and therefore the inner dimension is different. But overall, an AN4 pipe has ~ 1.5mm wall thickness and an AN12 pipe ~ 2.5mm wall thickness.
AN4 = 1/4" pipe OD = ~6,35mm
AN5 = 5/16" pipe OD = ~7,9mm
AN6 = 3/8" pipe OD = ~9,5mm
AN8 = 1/2" pipe OD = ~12,7mm
AN10 = 5/8" pipe OD = ~15,9mm
AN12 = 3/4" pipe OD = ~19,05mm
4. AN-key grip measurements
The key grip on AN fittings is also measured in inches and since European sizes are metric (millimeters), an adjustable socket wrench or inch tools is recommended during assembly so you get the correct engagement. There are special tools just for AN fittings, but a standard adjustable wrench works great.
AN3 = 1/2" = ~12,7mm
AN4 = 9/16" = ~14,3mm
AN6 = 11/16" = ~17,48mm
AN8 = 7/8" = ~22,23mm
AN10 = 1" = ~25,4mm
AN12 = 1-1/4" = ~31,75mm
AN16 = 1-1/2" = ~38,1mm
AN20 = 1-13/16" = ~46,0mm
