December '18

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36 THE SHOP DECEMBER 2018 D ash sizes, or -AN sizes, are com- monly believed to have originated in military applications, on aircraft, ships, tanks, etc., in order to create durable and reliable hydraulic, fuel and coolant plumbing. The tough, braided/reinforced hose, coupled with thread-on connections that were reliable in combat conditions, led early racers to buy military surplus hose, hose ends and fittings in the years following WWII and the Korean war. The racing community quickly latched onto this style of plumbing, resulting in common use in today's performance and racing markets. The term -AN (a common abbreviation for Army/Navy specification) sticks with us to this day. The reinforced hose/hose end assemblies are referred to as -AN assemblies (or simply AN assemblies, which means the same thing without the dash). The -AN hose sizing is based on single- and double-digit identification numbers. Common sizes for performance automotive applications include -3, -4, -6, -8, -10, -12, -16 and -20 (the larger the number, the larger the hose diameter). • -3 and -4 sizes are typically used for brake line applications, small oil lines, some small fuel line applications, pres- sure gauges and vacuum lines; • -6 size is typically applicable for fuel and oil plumbing; • -8 size is typically used for fuel, coolant and oil plumbing; • -10 size is typically used for oil, fuel or heater hose plumbing; • -12 size is typically used for coolant, large fuel delivery or dry-sump oil; • -16 size is typically used for coolant, dry-sump oil or large fuel delivery; • -20 size is typically used for coolant (radiator hose). The dash number refers to the hose's inside diameter, in increments of 1/16 of an inch. For example, a -10 size translates to 10/16-inch (5/8-inch) inside diameter. Think in terms of 1/16-inch increments. A -6 means that the inside diameter is 6/16 inches (or 3/8 inches) and so on. Not to make things confusing, but those 1/16-inch increments are nominal numbers that indicate the outside diameter (OD) of the hose end's internal metal tube (this tube slips into the hose). In reality, most AN hose makers actually make their hoses a bit on the tight-tolerance side, to the tune of about 1/32-inches smaller than the theo- retical nominal diameter size, which aids in hose sealing onto the hose end's tube. So, a -6 hose, which theoretically should have an inside diameter of 6/16 inches (3/8 or 12/32 inches), more than likely features an inside diameter of 11/32 inches. Nevertheless, using the 1/16-inch theory as your guide will help you to easily visu- alize what the inside diameter will be. -AN HOSE SIZING CHART SIZE NOMINAL I.D. ACTUAL I.D. OF THE HOSE 3 3/16" 1/8" 4 1/4" 7/32" 6 3/8" 11/32" 8 1/2" 7/16" 10 5/8" 9/16" 12 3/4" 11/16" 16 1" 7/8" 20 1-1/4" @1-1/8" NOTE: The above sizes are based on examples of Russell hose. Diameters may GET IT TOGETHER A basic understanding of –AN plumbing. By Mike Mavrigian -AN plumbing (hose, adapters and hose ends) provide excep- tionally reliable fluid connections. "Traditional" red/blue anodized hose ends remain popular today. Angle configurations are available for any routing. Silhouette view of -AN male threads, rang- ing from -3 to -20. (Photo courtesy Holley/ Earl's)

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