CGA V-5:2019

The Diameter Index Safety System defines noninterchangeable removable connections for use with medical gases at pressures of 200 psi (1380 kPa) or less. Removable, threaded connections are readily and commonly engaged or disengaged in routine use and service and are often found on regulators, resuscitation equipment, anesthesia equipment, therapy equipment, and other similar equipment.
The Diameter Index Safety System supplements but does not replace:
• any of the means for medical gas identification currently in use;
• the Pin Index Safety System;
• the existing threaded outlet standards for cylinder valves; or
• automatic quick coupler valves that also provide noninterchangeable connections for medical gases and suction equipment.
CGA does not designate where the Diameter Index Safety System should be applied.