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Air Line Fittings Explained

March 04, 2016

Air line fittings explained for air tools

Hi again,

Hope to shed a little light on the confusion surrounding the different types of air line fittings that are available on the market. I often ask customers what fittings they are using so we can supply the stapler/nailer with the correct fitting ready to go – often the reply is very confusing, they know what it looks like but cannot identify the type.

Let’s give it a go and try and give a little clarity.

Quick release couplings:

The quick release coupling is quite simply a means of quickly disconnecting an air line from air main or compressor and at the business end disconnect from air tool or equipment. The couplings have a shut off valve inside so when the male fitting is removed, the air flow is immediately shut down. The most common thread sizes are ¼” BSP and most of our tools have a ¼” BSP thread enabling the fitting of the male plug.

Schrader Coupling and Plug

Schrader Twistlok Standard Coupling

Schrader Twistlok Standard Coupling


This type of male plug is released by twisting the cap on the coupling and simultaneously twisting the hose to facilitate the disconnection.

PCL Standard Airflow Coupling and Plug

PCL Standard Airflow Coupling

PCL Standard Airflow Coupling

This type of male plug is simply disconnected by pulling back the collar on the coupling whilst holding the air line or tool connected to the male plug. Please note not holding the air line may cause the line to whip as the compressed air escapes. This type of Standard Coupling is a single action coupling designed for use in fixed applications such as compressor or air ring main.

PCL Standard Vertex Coupling

PCL Standard Vertex Coupling

PCL Standard Vertex Coupling

Used with the same male plug as above the Standard Vertex PCL coupling is a double action coupling which has been designed for use with trailing hoses. The protective shoulder is designed to stop the ingress of dirt and the accidental disconnection when lines are pulled along the ground or work bench.

PCL Standard Safety Coupling

PCL Standard Safeflow Safety Coupling

PCL Standard Safeflow Safety Coupling


This coupling prevents hoses from whipping when they are disconnected and are disconnected in a two stage process:

  1. Pull back the sleeve and the pressure will automatically vent via the body.
  2. Push the sleeve forward to the release the male plug


PCL Twin Standard Y Coupling

Twin Coupling PCL standard Y

Twin Y Coupling PCL standard

Used when you wish to split one line into two and is available with either Standard or Vertex Couplings.

Uni Hi Flow Coupling and Plug

Uni Hi Flo Connector with 1/4''' Male BSP Thread

Uni Hi Flo Connector with 1/4”’ Male BSP Thread

Another single action disconnection where the collar on the coupling is pulled back to release the male plug. This is the most common fitting we see on imported tools and air compressors.

Hose Tails

Brass BSPT Hose Tail

Hose Tails


Hose tails can be connected to couplings to enable fixing to air lines – tail sizes vary to fit different internal air line diameters.

There are many other types of fittings but I just wanted to cover the most popular fittings we come across and at least with a few images you may be able to identify what fittings you require. Hope this was of some assistance.

Read more on this subject by visiting Airlines and Quick Release Couplings Explained 

Hi Viz Airlines are here 

10 metre coil compressor airline here 

Compressors here

Compressor and airtool easy kits here  

Query here 

Until Next Time..... the very best of wishes

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