ISO 5167-3:2003规定了喷嘴和文丘里喷嘴在将其插入导管中时的几何形状和使用方法（安装和操作条件），以确定在导管中流动的流体的流量。 ISO 5167-3:2003还提供计算流量的背景信息，并结合ISO 5167-1中给出的要求适用。 ISO 5167-3:2003适用于喷嘴和文丘里喷嘴，其中流体在整个测量部分保持亚音速，流体可以被认为是单相。此外，每个设备只能在规定的管道尺寸和雷诺数范围内使用。它不适用于脉动流量的测量。它不包括使用管径小于50 mm或超过630 mm的管道喷嘴和文丘里喷嘴，或者雷诺数低于10 000。 ISO 5167-3:2003涉及两种类型的标准喷嘴，ISA 1932喷嘴和长半径喷嘴，以及文丘里喷嘴。 两种类型的标准喷嘴基本不同，并在ISO 5167-3:2003中单独描述。文丘里喷嘴具有与ISA 1932喷嘴相同的上游面，但是具有发散部分，因此具有不同的位置用于下拉

ISO 5167-3:2003 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. ISO 5167-3:2003 also provides background information for calculating the flow-rate and is applicable in conjunction with the requirements given in ISO 5167-1. ISO 5167-3:2003 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. In addition, each of the devices 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 pipe Reynolds numbers below 10 000. ISO 5167-3:2003 deals with two types of standard nozzles, the ISA 1932 nozzle and the long radius nozzle, as well as the Venturi nozzle. The two types of standard nozzle are fundamentally different and are described separately in ISO 5167-3:2003. 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. For both of these nozzles and for the Venturi nozzle direct calibration experiments have been made, sufficient in number, spread and quality to enable coherent systems of application to be based on their results and coefficients to be given with certain predictable limits of uncertainty.