JJF 2033-2023 "Specification for calibrating orifice Flow rate meters" applies to the calibrating of orifice Flow rate meters. This specification refers to a number of related documents, including differential pressure Flow rate meters, general Measurement terms and definitions, Flow rate Measurement terms and definitions, etc. The specification describes in detail the measurement uncertainty assessment and representation methods, and covers the specific requirements and principles for the measurement of full tube Fluid Flow rate by differential pressure devices for circular section pipelines. In addition, it also includes the technical requirements and detection methods of orifice flow rate meters in the fields of environment air particulate matter (PM) sampling and total suspended particulate (TSP) sampling. For referenced documents, only the specified date version is applicable, and the undated referenced documents are subject to the latest version.