When working with A-N fittings and hose, sooner or later you'll come across terms that are pretty foreign. What you have is a bunch of racer-speak mixed with aircraft lingo. And unless you have a good handle on it, you'll never figure out what's going on. In order to wade through the murky waters, take a look at the following plumbing glossary. It's a quick way to walk the walk and talk the talk.

A-N Flare: The flare shape found inside an A-N fitting is 37 degrees. This is not the same as a SAE flare.

A-N: The term "A-N" stands for "Army-Navy". A-N "air corps" standards were established before WWII so that military hardware, sizes, specifications and configurations could be standardized. When plumbing a car, we use A-N numbers to determine a size. This is only part of the complete A-N ID number. Generally speaking, A-N numbers refer to outside diameters, in increments of 1/16th of an inch.

a d v e r t i s e m e n t

Click to visit our sponsor's website

Adapters: Almost all automotive fluid handling applications use pipe threads. Because of this, parts with pipe threads aren't compatible with the A-N fittings and adapters must be used. For the majority of A-N applications, adapters are manufactured from aluminum. Certain situations mandate steel adapters, but these are seldom used in hi-po automotive applications. Adapters are available in countless sizes and shapes.

Banjo: A "banjo" fitting is usually a hose end with a circular shape on one side. A special bolt with a series of holes machined in it (appropriately called a "banjo bolt") seals the fitting to the parent part. Banjo fittings are usually found on brake lines and are sometimes used on carburetor inlet fittings.

Barb Hose End: This is a simple system. Essentially, the hose is pushed over a series of annular "barbs" found on the hose end (or nipple). A simple hose clamp is installed just behind the last barb to hold the works in place. While simple and effective, don't expect a barb style hose end to work under extreme pressures.

a d v e r t i s e m e n t

Click to visit our sponsor's website

Bent Tube Hose End: This type of hose end uses a formed, bent tube to join the hose retention area and the threaded A-N end of the fitting. They provide the best flow characteristics of any hose end that must make a bend. Bent tube hose ends are available in 45°, 90°, 120°, 150° and 180° configurations.

Bulkhead Nuts: Bulkhead nuts are threaded in A-N sizes and are used to secure bulkhead fittings to (appropriately) a bulkhead or panel. See "Bulkhead".

Bulkheads: Bulkhead fittings are often used as through-panel connectors. These are double male end fittings with an extra set of A-N threads which allow the use of a "bulkhead nut" to hold the fitting in place.

Double Nipple Hose End: This is the common "cutter" hose end. It uses a double nipple which has two separate parts. In practice, the nipple tube slips inside the hose. But further up the assembly is another nipple or cutter. Without going into detail, the pair of nipples (one being a cutter) act as two separate seals on the hose end. This eliminates any blow-off, especially if modern lightweight hose is used in the system. If there is a knock on double nipple hose ends, it's the fact that it tends to chew up the hose during assembly (although you can't see it).

a d v e r t i s e m e n t

Click to visit our sponsor's website

Elbows: Elbow fittings are simply 90° versions of a flare union. Elbow fittings almost always have identical A-N threads on ether end.

Female Coupling: Also an adapter fitting, this design is the female version of a pipe nipple. Generally speaking, these adapters have identical thread sizes on both ends.

Flare Reducer: A flare reducer is similar to a flare union, but one side is smaller than the other (i.e.: one side might be -6 A-N while the other might be -8 A-N).

Flare Union: A flare union is the A-N equivalent of a pipe nipple. It features male A-N threads on both sides. And both sets of threads are identical.

Forged Hose End: "Forged" hose ends are designed with "angular" bends rather than gentle bends (as found in bent tube hose ends). They're primarily used in locations that have tight clearances. In most cases, forged hose ends are available with 45° and 90° bends. Use this hose end when a bent tube will not fit in a low clearance application.

Hard lines: Hard lines are just that -- hard. Typically, when plumbing a car, you'll run into some locations that require this form of line (i.e.: a brake line). In most cases, OEM hard lines will be plumbed with SAE flares. After market hard lines can be made with SAE flares or A-N flares.

Hose Barbs: These are the single nipple ends commonly found on brass fittings. The hose slips over the barb, then a hose clamp ties the works together.

Hose Ends: Hose ends are fittings which attach directly to the hose. They can be sophisticated "cutter designs" or more common configurations such as clamp-on assemblies. Hose ends are available in a wide range of shapes, sizes, bends, and end styles.

Hose: Hose usually refers to stainless steel braided flexible hose used when plumbing A-N components. it's sold in various types (neoprene lined, Teflon lined, etc.), and size is determined by the A-N number. Various grades of hose are available.

"O" Rings: "O" rings are used to seal straight thread ports and banjo fittings (both of which are machined to accept an "O" ring). Typically, "O" rings are manufactured from either synthetic rubber or Viton. Viton has more scuff resistance, offers a longer service life and has a higher temperature rating of 400° F.

Pipe Nipples: These are a subgroup of the adapter. They feature male pipe threads on both ends. Both ends can either be the same or have different thread sizes.

Pipe Thread Sealant With Teflon: Pipe thread sealant with Teflon has virtually replaced Teflon tape. It's far easier to use and is more effective. No, it isn't the same as household plumbing sealant. The sealant is anaerobic and is designed to completely fill the voids between mating threads. See "Teflon tape".

Pipe Thread: Pipe thread, tapered pipe thread or "National Tapered Pipe" thread sizes refer to the inside diameter of a piece of pipe that receives the male end. It's designed for an interference fit between the male and female threads (hence the taper which becomes larger as the two parts are tightened). Supposedly, this interference fit is engineered to stop leaks. Unfortunately, it doesn't work that way and some form of sealant is required (see Teflon tape). Most cars use some form of pipe thread on various "fluid handling" components.

Push-On Hose End: See "Barb Hose End".

SAE Flare: The shape of an American double flare is 45 degrees. It cannot seal against an A-N flare of 37 degrees.

a d v e r t i s e m e n t

Click to visit our sponsor's website

Single Nipple Hose End: Single nipple hose ends were primarily used with early type heavy-wall flexible hose. Generally speaking, this is much like heavy duty hydraulic hose, and by nature, it is heavy. Further to this, some single nipple hose end designs tend to blow off the end of the hose -- especially if modern, thin-wall hose is incorporated. Fortunately, contemporary, well designed single nipple hose ends are engineered to eliminate this phenomenon, and they've become one of the standards of the racing industry.

Stat-O-Seal: These are special sealing washers that have a synthetic rubber "O" ring mechanically locked to the washer ID. When tightened, the "O" ring is compressed, forcing the sealing surfaces around the thread shanks.

Swivel Seal: This is an Earl's trade mark. The patented Swivel Seal hose end is designed to swivel (or adjust radially) after it has been assembled. Other companies now offer similar hose ends which can be adjusted radially.

Teflon Hose: Teflon hose is commonly used in applications that mandate very high pressures. A good example of the use is in brake hose applications. Teflon lined hose is not as flexible as neoprene lined hose. Additionally, special fittings (designed for use with this hose type) are required.

Teflon Tape: Due to the nature of pipe threads (they taper), some sort of sealant is required. Before pipe thread sealant with Teflon was released, the only answer was Teflon tape. In use it is added to the male threads on a pipe fitting. As the fitting is tightened, the tape fills the voids on the mating threads, eliminating leaks. Teflon tape is not used to seal A-N threads. That's the job of the integral conical seal.