AN hoses and fittings are often found installed on high performance and race cars. AN hoses are used for fuel, oil, coolant and hydraulic fluids. AN stands for Army-Navy as the specification was developed based on a standard for flexible fluid connections used during World War II. They are often used in aviation but like most high performance aviation equipment they eventually ended up on race cars and then street cars.
People use AN fittings because they look cool and provide a secure fitting that seals hoses better than traditional push on nipples and hose clamps. They form a serviceable connection that provides a reliable seal. AN fittings can also be used for leak free bulkhead pass throughs like those found on the outside of fuel cells.
AN Fitting Types
There are 4 common types of AN fittings connections. These relate to how the hose is connected, including:
Push on barbed fittings are for use with soft rubber hose or "sockeless" hose. Hose and fittings are easy to install: they simply push on with some heat and lubricant, and "lock" in place. The hose will not slide off the fitting easily because it compresses on the fitting as pressure increases.
PTFE Hose End, people also call it Teflon hose end. PTFE is chemically inert. It will not break down or deteriorate in service, and it has an unlimited shelf life because properties do not change with age or exposure to weather. PTFE hose can be used in aerospace, automotive, chemical and industrial applications.
AN Sizes
The AN sizing can be confusing at first but once you get used to it you can tell the size just by looking at the fitting. The AN size reference the Outer Diameter of hose in 1/16th of an inch increments. For example a -3 AN hose has an external diameter of 3/16th of an inch. Similarly -8 AN hoses are 8/16 = 1/2 inch in outer diameter.
The most common uses of AN hoses on race cars:
-3 AN fittings used for brake lines
-4 AN fuel hoses
-6 AN fuel or coolant hoses
-8 AN a very common size for coolant and oil
-10, -12 AN fittings are used on either coolant or vent hoses
AN Hose Types
PTFE fuel line can be used as fuel injection hose, turbo oil feed and boost line, transmission oil cooler line, EFI fuel line, carb fuel line, ls engine swap fuel line, fuel return line, vapor return line, vacuum line, fuel supply line and other high temperature high pressure
Double soft stainless steel braided hose
Inner layer: CPE synthetic rubber
The middle layer: 304 stainless steel wire mesh sleeve
The outer layer: High-quality stainless steel
Nylon&stainless steel braided hose
Inner layer: CPE synthetic rubber
The middle layer: 304 stainless steel wire mesh sleeve
The outer layer: High quality braided nylon
Push on fitting rubber fuel hose
Rubber hose is suitable for push-lock hose ends
AN Fitting Adapters
There are a variety of different adapters and fitting types that can be used to interface AN hardware with engine blocks, cylinder heads, radiators and oil coolers.
AN Tools
AN fittings are commonly made of aluminum and can be marred by standard wrenches. There are specific aluminum AN wrenches that are made of anodized aluminum to prevent damage to the surface of the fittings.