This part of EN ISO 5167 specifies the geometry and method of use (installation and operating conditions) of nozzles and Venturi nozzles when they are inserted in a conduit running full to determine the flow-rate of the fluid flowing in the conduit. This part of EN ISO 5167 also provides background information for calculating the flowrate and is applicable in conjunction with the requirements given in ISO 5167-1. This part of EN ISO 5167 is applicable to nozzles and Venturi nozzles in which the flow remains subsonic throughout the measuring section and where the fluid can be considered as single-phase and which can only be used within specified limits of pipe size and Reynolds number. It is not applicable to the measurement of pulsating flow. It does not cover the use of nozzles and Venturi nozzles in pipe sizes less than 50 mm or more than 630 mm, or for pipes where the Reynolds numbers are below 10000. This part of EN ISO 5167 deals with: a) two types of standard nozzles: 1) the ISA 1932 nozzle; 2) the long radius nozzle; b) the Venturi nozzle. The two types of standard nozzle are fundamentally different and are described separately in this part of EN ISO 5167. The Venturi nozzle has the same upstream face as the ISA 1932 nozzle, but has a divergent section and, therefore, a different location for the downstream pressure tappings, and is described separately. This design has a lower pressure loss than a similar nozzle.