This specification covers **breathing systems and components employed with anesthesia gas machines for humans.**

This specification considers the circle system as a whole and some of its components individually. A particular emphasis is placed upon **component arrangement in the circle absorber-type system,** and submits a system of standard description and notation.

The circle system is divided into four segments:

• Segment 1 - from patient to expiratory valve,
• Segment 2 - from expiratory valve to reservoir bag,
• Segment 3 - from reservoir bag to inspiratory valve, and
• Segment 4 - from inspiratory valve to patient.

Leakage of breathing system and resistance of breathing system shall be tested to meet the requirements prescribed.

The adjustable pressure-limiting valves, reservoir bag connectors and reservoir bags, carbon dioxide absorbers, unidirectional valves, and optional components shall meet the requirements prescribed.

1.1 This specification covers breathing systems and components employed with anesthesia gas machines for humans. This specification considers the circle system as a whole and some of its components individually. A particular emphasis is placed upon component arrangement in the circle absorber-type system, and submits a system of standard description and notation. Excluded are ventilators for use during anesthesia, Mapelson nonrebreathing type systems, as well as breathing systems and related components of dental analgesia machines. (For rationale, see Appendix X1.)

1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

1.3 This specification is arranged as follows:

• Scope
• Referenced Documents
• Terminology
• System Classification
• Graphic Notations
• Diagrammatic Rules
• Functional Segments of the Circle System
• Test Procedures-General
• Sterilization
• Systems
• Leakage of Breathing System
• Resistance of Breathing Systems
• Volume of Gas Not Delivered to Patient Due to Internal Compliance
• Monitoring Requirements
• Adjustable Pressure-Limiting (APL) Valves
• Reservoir Bags
• CO₂ Absorbers
• Unidirectional Valves
• Requirements
• Test Procedure
• Optional Components
• Breathing Tubes
• Fresh Gas Inlet and Fresh Gas Supply Tube or Hose
• Connectors
• Pressure Gauges
• Y-Piece and Breathing Tubes
• Information in Labeling
• Rationale