What is a CRN?

CRN stands for Canadian Registration Number.  Unless exempt, all pressure equipment must be registered with a CRN before use in Canada.  It's the law here. Literally hundreds of thousands of them exist, and they only exist in Canada. Their assignment, nomenclature, use, and requirements are referenced in CSA B51, a the Canadian Pressure Vessel and Pressure Piping Code, that is enacted into law by pressure equipment legislation in all Canadian jurisdictions.  They are sequentially assigned in Canada by provincial regulatory jurisdictions. They are used to identify and organize distinct pressure equipment design concepts in a manner that permits all Canadian jurisdictions to identify and distinguish the designs apart from each other, pursuant to assigning responsibility for the use of pressure equipment in Canada. They are not the same as a certification marking such as CSA, UL, ETL, etc. which are issued by quality assurance companies and agencies.  CRNs are issued by jurisdictional pressure equipment regulators.  They relate to the acceptance of design concepts, and though those concepts must meet some testing specified after the conept is built, the test results of those conceptual tests are not necessarily always known before the CRN is issued.   Conversely, certification marks indicate that physical equipment has passed phsical testing requirements and has thereby met published standards.