There are many terms that are unique to the hose industry. If you don’t understand what is being said, how do you know your customer will get what they want? The words “fitting” and “coupling” are often mixed up or used interchangeably; it is important to understand the difference.

What is a Fitting?

A fitting is a single connection between a hose and a threaded connection. A fitting stands alone, not in a set, and can have dozens of different thread configurations. It may also be threaded on both ends with different sizes and thread types. These are usually referred to as adapters.

What is a Coupling?

Couplings are a set of units that are used together. They can be sold separately or in sets. Some couplings have hose ends while others have threaded ends. They can have male, female, or universal ends when both connection ends are the same.

3 Types of Couplings

There are three main types of couplings: straight through, single valve, and double valve.

Straight Through - No Valve

A straight through coupling does not have a valve. It is used for high-volume transfer. Some examples from Dixon include cam & groove, Boss^® ground joints, Dix-Lock^®, E-series, and Air King^®. When connected to a mating part, the flow will not be diminished by a valve.

Single Valve

Primarily used in pneumatic applications, the valved coupler on the hose will shut off airflow when disconnected, and the unvalved plug will allow the air to vent out of the tool. This is why you can hear the sound of air releasing when you disconnect an air tool. Without using a single valve shut off, the tool might still be energized even though the hose is disconnected. For example, think of the danger a charged nail gun could present.

Double Valve

Double valve couplings are mainly used in hydraulic systems. Both sides have valves to stop the flow of oil when the coupling is disconnected. There are many different series of hydraulic quick disconnects designed for different services. Components such as body material, seal material, pressure rating, and flow can vary depending on which series you choose. Dixon dry disconnects are an example of double valve couplings.

Summary

Understanding hose industry terminology is important to ensure you have The Right Connection^®. Dixon manufactures and supplies a variety of fittings and couplings for applications across many industries. For more information, visit dixonvalve.com or call 877.963.4966.