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Inflator hoses and their differences

One of the bestsellers in our Scuba Service Tools webshop is the "Inflator connector O-ring tool set" this tool set fits the most common inflator hose couplers.

But occasionally an email comes in saying that the tool doesn't fit in the inflator hose coupler.

Usually, after some explanation on how to use the tool it works out, but it also occurs that the customer tries to use the tool on a not-so-standard inflator coupler.

In this article, we would like to show you that there are many different types of couplers and nipples on the market.

To give you a bit of an impression, these are the four we found on the first page after a little searching on Google using the phrase "standard scuba inflator nipple". As you can see all 4 of them are different.

In the picture below you can see there are many differences in the (according to the market) standard nipples. This is the main reason that inflator hoses usually fit

But it is not always guaranteed that air will come out. That again depends on the type of Schrader valve in your hose.

Four different scuba inflator couplers
Scuba inflator couplers
Scuba inflator hose Schrader valve
Schrader valve


-Thread size

-Opening size

-Small holes


One of the main reasons for this is that they are not only used on Scuba inflators, but also on Drysuits, Lift bags, Decompression buoys, Full face masks, and more...

This is also the main reason that they have different airports. For example, a lift bag naturally requires much more air than a scuba regulator.

But also because, for example, a drysuit connector hose is designed very differently from a standard inflator hose (we will come back to this later in this blog).

Differences in application

As previously mentioned, scuba inflator couplers and nipples are used in many ways in the diving industry and are certainly not only found on the inflator of your BCD.

Below are some of the different applications for scuba inflator couplers.

An often-forgotten but certainly not unimportant point is that scuba gear has often had several owners. When an old set is replaced with a new one the used set is usually sold.

The new owner may like to dive with a different setup and so it can happen that hoses are moved or exchanged.

As a result, it often happens that scuba service centers are offered regulator sets with inflator hoses that are actually intended for a different purpose.

Scubapro AIR2, Aqualung Airscource, and the older Buddy Auto AIR

These are a second stage and an inflator in one and have been around for many years in the diving industry. At most scuba manufacturers you can find a type of this kind of regulator.

For example, Scubapro already came out with its 5th generation of the Scubapro AIR2.

Scubapro AIR2 coupler
Scubapro AIR2 connection

These regulators/inflators use a slightly different inflator coupler than the standard inflator coupler.

Both the coupler and its opening are a lot larger because this scuba regulator must be able to fill a BCD and supply air to the diver at the same time. There are Gradient adapters on the market that convert the large connection back to a standard inflator connection. We do not recommend using this adapter because it cannot suffice if an emergency occurs during a dive and a larger airflow is required.

Differences in inflator hose design

There are many inflator quick disconnect couplers on the market, the most common being the DIN, CEJN, and the larger AIR2/AIRSOUCE/BUDDY coupler (we will not consider the latter here).

The DIN coupler

There are many inflator quick disconnect couplers on the market, the most common being the DIN, CEJN, and the larger AIR2/AIRSOUCE/BUDDY coupler (we will not consider the latter here).

The DIN coupler is the most common of the 3 and is the simplest in design.

It functions by opening and closing a Schrader valve which is also its weakest link.

This Schrader valve stops working when it is not kept clean and too much corrosion is deposited. Also, replacing the wrong Schrader valve length during service is the main cause of BCD failure.

The CEJN coupler

The couplings of the CEJN brand have been used for years in hydraulics and pneumatics why this coupling is still not the standard in the diving industry is a question to us.

The big advantage over the DIN coupling is that it does not have a Schrader valve and is therefore less sensitive to corrosion and dirt. it is also excluded that a scuba technician accidentally installs the wrong size Schrader valve.

Remember that inflator hoses can also be used on drysuit valves, If you opt for a hose for a drysuit, remember that you make sure you have a hose coupler with a larger outer ring and preferably a CEJN coupler as you don't have to push the hose in before you pull the collar back with your clumsy neoprene or dry suit gloves.

Diving on Demand / Scuba Service Tools accepts no liability for the information given in this document.

Our documents are to provide a general understanding of SCUBA diving-related topics, and not to provide specific advice.

Most authorized dealers are able to perform warranty, repair, and service work on your equipment. Availability of sub-assemblies and components, repair parts, specialized tools, maintenance guides, and service manuals does not imply qualification to assemble and/or service scuba equipment. Improper service of dive equipment can lead to serious injury or death.


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