CSA B149.3:25

1 Scope 1.1 Inclusions This Code contains the requirements for fuel-burning appliances and equipment located downstream of the manual shut-off valve specified in Clause 6.18.2 of CSA B149.1. 1.2 Exclusions This Code does not apply to a) installations in marine pipeline terminals; b) gas where used as a feedstock in petroleum refineries or chemical plants; c) gas designated for storage or handling, or both, at propane gas bulk plants; d) gas where used for natural gas for vehicles; e) a new appliance that is certified to an approved Standard; f) a manually operated appliance with an input not exceeding 20 000 Btu/h (6 kW) used for industrial applications; g) other fuels not covered in this Code and used in combination with gas; and h) a certified appliance when changing the fuel type with a certified conversion kit for the appliance. 1.3 Application Requirements contained in this Code apply only to that portion of an appliance using gas as defined in Clause 1.6, atmosphere gas, and reaction gas. 1.4 Types of appliances and controls The requirements contained in this Code apply to a) an appliance that is not certified to an approved Standard; b) a previously certified or previously field-approved appliance where the certification or approval has been voided due to a modification of the appliance installation or control system; and c) programmable logic controllers or microprocessor-based controls used for flame safety and fuel-air ratio control. 1.5 Hierarchy For an appliance for which there is an approved standard, the requirements in this Code may replace or supplement the requirements in an approved standard to achieve a field approval under this Code, with the permission of the authority having jurisdiction (AHJ). 1.6 Gas type When the term “gas” is used, the requirements of this Code include, and apply equally to, any of the following gases or mixtures of them: natural gas, manufactured gas, propane, propane air, propylene, butane (normal butane or isobutane) butylene, hydrogen and hydrogen – natural gas blends. 1.7 Biogas When using biogas, this Code is to be used in conjunction with CSA/ANSI B149.6. 1.8 Units of measurement The values given in US customary units are the units of record for the purposes of this Code. The values given in parentheses are for information and comparison only. 1.9 Terminology In this Code, “shall” is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the Code; “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 Code. 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.