Plumbing Fundamentals – AN Fittings and Hoses

AN connectors and tubes are frequently encountered in high-performance and race vehicles. Gas, petroleum products, cooling water, and hydraulic fluids are all carried using AN hoses. The acronym AN refers to Army-Navy, as its specification was inspired by World War II standards for flexible fluid interconnections. They are frequently used in aircraft, but as with most other high-performance aircraft equipment, they soon made their way onto racing vehicles and later street automobiles. To produce a metal-to-metal connection, AN employs a 37-degree flared joint.

People choose AN fittings because they have been visually appealing and provide a secure connection that closes pipes better than typical push-on and pipe clamps. They establish a durable seal and form a functional connection. AN connectors can sometimes be utilised to provide leak-free firewall pass-throughs, such as those seen on the exterior of fuel cell technology.

Types of AN Fittings

Three types of AN connectors are commonly used on racing cars or highly tuned automobiles. These are affiliated to how the pipe is attached and possess:

  • Crimping style
  • Hose ends that are reusable
  • Push-button lock

All of them may also be non-swivel or rotate, making installation handy.

Compression type fittings are often used in facilities that manufacture a large number of hoses since they demand a hydraulic press with particular dies to correctly crimp its collar onto the pipe ends. Because these types of equipment and dies are costly, they are rarely employed by individuals or small racing teams.

The Crimp type hose needed a different crimp collar to be recycled, however, when crimped properly, it is regarded as the strongest and most dependable fitting. Reusable pipe ends and push-lock are the two most typical varieties employed by private mechanics or minor race teams. This is because they can be installed and repaired with hand tools.

To keep the hose in position, the reusable pipe ends employ a two-part mechanism. They are often used either stainless metal or nylon woven hose. They are available in a range of diameters, elevations, and colours. They are noticeably heavier than push clamps, but they are said to offer a more robust hose clamping approach. The pipe end connectors are separated from the body by threads. After that, the braided tubing is placed into the connector. The connector is threaded over the nozzle during installation, pushing the hose internal diameter over the curve. To deal with pressure and avoid leaks, the curves and features hold the hose in position. To produce a full seal on the curved surface, the feminine nut end is screwed into the matching male fitting. Push-lock tubes are the simplest to construct since they are one-piece items with a barbed end. Push plugs are used with covered hoses because they lack a mechanism that keeps the braids from unravelling. The tube is seated after being pushed over the barbs. The barb could be used alone to secure the hose, or an extra clamp can be utilised.

AN Dimensions

The AN measurement might be perplexing at first, but after you are used to it, you can discern the sizes just by glancing at the fitting. The AN size refers to the hose’s outside diameter in 1/16th-inch increments. A -3 AN pipe, for reference, has an exterior dimension of 3/16th-inch.  Likewise, -8 AN hoses have an outside dimension of 8/16 = 1/2 inch.

The following are by far the most prevalent use for AN hoses in race cars:

For brake lines, -3 AN fittings are utilised.

Fuel hoses -4 AN

Hoses -6 AN for gasoline or coolant

-8 AN is a popular size for both coolant and lubricant.

Either in coolant or vent hoses, -10 and -12, AN connectors are utilised.

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