Diameter-Index Safety system (DISS)

The Compressed Gas Association (CGA) developed the Diameter-Index Safety system (DISS) to establish a standard for non-interchangeable, removable connections for use with Medical Gases, Instrument Air, Vacuum (Suction), and WAGD (Waste Anesthetic Gas Disposal). Non-interchangeable indexing is achieved by a series of increasing and decreasing diameters in the components of the connections. These specific diameters act in key-like fashion, so that fittings within the gas service “family” will connect only with their own “family members.”