ORB Fitting -06 ORB | -08 AN

AN (Army-Navy) fitting sizing refers to a standardized system used to identify the size of aircraft and military fluid line components, including hoses, fittings, and connectors. These fittings are primarily used for fuel, hydraulic, and other fluid systems in aerospace, military, and high-performance automotive applications. The AN fitting system was developed by the U.S. military and is based on precise measurements and tolerances to ensure proper fluid flow and safety. Here’s a breakdown of how AN fitting sizing works:

1. Dash Number System

AN sizes are designated by a "dash number," which corresponds to the outer diameter of the fitting or hose in sixteenths of an inch. For example:

• AN-4: This refers to a fitting or hose with an outer diameter of 4/16", or 1/4 inch (0.250").
• AN-6: This refers to a fitting or hose with an outer diameter of 6/16", or 3/8 inch (0.375").
• AN-8: This refers to a fitting or hose with an outer diameter of 8/16", or 1/2 inch (0.500").

The dash number (e.g., AN-4, AN-6, AN-8, etc.) refers to the size of the hose or fitting in 1/16-inch increments.

2. Thread Size

AN fittings have specific thread types, often referred to as 30° flare fittings. The threads are typically MIL-Spec (Military Standard), which are compatible with certain flare type fittings. These threads are made to tight tolerances to ensure a leak-proof seal. For example:

• AN-4 fittings generally have a 7/16"-20 UNF thread (fine threads with 20 threads per inch).
• AN-6 fittings usually have a 9/16"-18 UNF thread.
• AN-8 fittings typically have a 3/4"-16 UNF thread.

3. Material and Construction

AN fittings are typically made from high-strength materials like aluminum, stainless steel, or brass, depending on the application. The construction of the fitting is designed to ensure maximum durability under extreme pressure and temperature conditions.

4. Flare Type

AN fittings use a 37° flare on the mating surfaces. This is different from other common flare angles like the 45° flare found in other fitting standards (such as JIC). The 37° flare ensures a tight seal and is critical in high-pressure systems.

5. Different Fitting Types

• Straight fittings: These are used to connect two hoses or pipes in a straight line.
• Elbows: These are used to change the direction of a hose or pipe, typically available in 45°, 90°, and 180° angles.
• Tees and crosses: These fittings allow for the branching of fluid flow into multiple directions.
• Bulkhead fittings: These are used to mount fittings through a wall or barrier.

6. Application

AN fittings are commonly used in aviation and motorsport industries, where they are ideal for high-performance fluid systems due to their durability, ease of use, and leak-proof sealing. They are often used in applications like:

• Fuel lines
• Hydraulic systems
• Brake lines
• Oil lines

Summary of AN Sizing:

• AN-4: 1/4 inch (0.250" OD)
• AN-6: 3/8 inch (0.375" OD)
• AN-8: 1/2 inch (0.500" OD)
• AN-10: 5/8 inch (0.625" OD)
• AN-12: 3/4 inch (0.750" OD), etc.

When selecting AN fittings, it's crucial to match the correct fitting size to the hose or component size to ensure proper fitment and leak-free operation.