Scope 1.1 This Standard provides the minimum requirements, unless otherwise specified by the authority having jurisdiction, for the purity of compressed breathing air supplied to the service outlet and for breathing air systems required to produce, store, and distribute such air. 1.2 This Standard is limited to compressed breathing air and compressed breathing air systems used in the following applications: a) supplied-air respirators; b) supplied-air suits; c) self-contained breathing apparatus (SCBA) (open circuit); d) ambient air systems; and e) other applications for which qualified persons deem it appropriate to reference the compressed breathing air purity requirements described in this Standard, e.g., vortex tubes used for heating and cooling supplied-air suits. Notes: 1) Implementation of the requirements of this Standard within a respiratory protection program is addressed in CAN/CSA-Z94.4. 2) The manufacturer, the applicable testing agency, and the authority having jurisdiction should be consulted for quality requirements for breathing gas in closed-circuit SCBA. 3) For diving operations, refer to CSA Z275.2. 1.3 This Standard includes requirements applicable to the design, construction, commissioning, calibration, testing, operation, and maintenance of components for compressed breathing air systems. 1.4 In this Standard, "shall" is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the Standard; "should" is used to express a recommendation or that which is advised but not required; and "may" is used to express an option or that which is permissible within the limits of the Standard. Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate from the text explanatory or informative material. Notes to tables and figures are considered part of the table or figure and may be written as requirements. Annexes are designated normative (mandatory) or informative (non-mandatory) to define their application.