Differential Pressure Devices in accordance with ISO and other standards
The measurement of flow rate with the aid of differential pressure devices in accordance with ISO 5167 represents the only globally standardised procedure which defines calculating the uncertainty of the measurement. This measuring procedure has proven itself over many years and is applicable for all common media.
The design forms can be divided into orifice plates, nozzles and Venturi tubes.
The method is not subject to any limitations in respect of pressure, temperature or nominal diameter. Differential pressure devices are employed especially for the measurement of vapours. With the selection of suitable materials and the suitable differential pressure device, nearly every application is possible. Thanks to the improvement of the differential pressure transmitter, today a significantly higher turndown is also possible. Furthermore, the replacement of electrical components without interrupting the flow of the medium (no operating downtime) and the relatively low purchase costs are additional advantages of this form of flow measurement, even with larger nominal diameters. Flow restrictors or multi-hole orifice plates are designed in accordance with ISO 5167 and serve for the reduction of pressure in pipelines.