This standard applies to: – Flow-metering devices which are connected and disconnected by the operator at terminal units of a medical gas pipeline system for measurement and delivery of medical gases. They can be connected either directly or by means of flexible connecting assemblies. – Flow-metering devices which are connected and disconnected by the operator at gas-specific connection points of devices such as pressure regulators. It applies only to flow-metering devices for the following medical gases: Oxygen; nitrous oxide; air for breathing; carbon dioxide; helium; xenon; specified mixtures of the gases listed above; oxygen/nitrous oxide mixture (50/50 % V/V). Electrical or electronic flow-metering devices are excluded from the scope of this standard.