Sleeve Index System (SIS)

The Australian Standard AS 2902 specifies the Sleeve Index System. (You do not need to know the Standard number).

The fittings use a standard Whitworth screw thread, which means that the threads are the same size for each gas. The fittings are made non interchangeable by the presence of the sleeve.

IF YOU REMOVE THE SLEEVE THE CONNECTOR IS NO LONGER GAS SPECIFIC.

If you want to complain about a non standard fitting, you need to choose your words carefully. There is no legal requirement to comply with AS 2902. The TGA will approve products for use in Australia which do not comply with this standard, as long as they do not claim to be compliant.

New Zealand does not require compliance with AS 2902.

There are defined fittings for:
Oxygen
Nitrous Oxide
50/50 Oxygen / Nitrous Oxide mix
Medical Air
Variable Air/ Oxygen mixtures
Surgical Tool Air
Suction
Scavenging
Medical Carbon Dioxide
Oxygen / Carbon Dioxide Mixture
Oxygen / Helium mixtures)

It is NOT necessary to memorise this list!

Below is an SIS fitting supplied by a major company with the sleeve removed. The hose would fit any SIS outlet.

Non Interchangeable Screw Thread (NIST)

ISO standard 5359 defines the Non Interchangeable Screw Thead.

These are made non interchangeable by the size of the threaded connection. AS 2902 specifies that NIST should be used for gases with no SIS fitting defined.

As they are in the Australian Standard, you should know something about them, although if you normally use SIS fittings, you would not be examined in depth on this connector.

Diameter Indexed Safety System (DISS)

This is the American standard. The fittings are made gas specific by the diameter of the thread. You can find a description in Dorsch.

You would only be asked about DISS fittings if you nominate these connectors as being those used in your hospital.

Schrader Indexed Probe

The UK use the Schrader Indexed Probe, which is briefly mentioned in Al-Shaik & Stacey. Ward also references it in Chapter 1.

They are made gas specific by the collar. If the collar is removed the probe will fit any outlet.

The collar may be fitted with a notch, if the application requires a specific orientation such as a flowmeter. You can see one of these notches on the lowest connector shown here.

Quick connect indexed probes are specificly precluded from the Australian Standard because they can whip through the air when disconnected.

Other Connectors

Other countries may have their own specific standards, with yet more different fittings. Germany uses a DIN fitting, which you may see on some Dräger ventilators.

DIN Wall Connector

I was puzzled for years as to why Dräger had pictures of pistols next to some of the pressure gauges on their anaesthetic machines.

I finally figured things out when I saw the DIN wall connectors for low pressure gas assemblies.

(This is here for interest. German gas connectors are not examinable.)