| Zugriffsnummer | 34375 |
| Dokumenttyp | Konferenzartikel |
| Sprache | Englisch |
| Titel | A new calibration method for ultrasonic clamp-on flowmeters |
| Autor(in); Institution |
Funck, Bernhard; Flexim GmbH, GERMANY
Panicke, Mathias; Flexim GmbH, GERMANY
Kublay, Erkan; 1.5, Flüssigkeiten, PTB-Braunschweig
Engel, Rainer; 1.5, Flüssigkeiten, PTB-Braunschweig
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| Quelle/Jahr | International Flow Measurement Conference 2015 - Advances and Developments in Industrial Flow Measurement:(2015), 19 S. |
| URL | |
| Konferenzangaben | International Flow Measurement Conference 2015: Advances and Developments in Industrial Flow Measurement, Coventry, 01-02, July, 2015, UK |
| Freie Schlagworte | Ultrasonic flow meter ; Clamp-on flow meter ; Calibration ; Laser-Doppler Anemometry ; Fluid mechanic calibration factor |
| Zusammenfassung | Ultrasonic clamp-on flowmeters measure non-invasively. The transducers are installed on the outside of the pipe at the measurement location in the field. Therefore, a factory calibration of a clamp-on flowmeter cannot include a meter body. Conventionally, when a calibration for a clamp-on flowmeter is required, it is per-formed at a calibration facility designed for invasive flowmeters. This means that the pipe and the flow profile conditions of the calibration facility are part of the calibration although the pipe is not delivered with the flow meter into the field. This is a valid method if the flow conditions can be assumed to be ideal and the uncertainty in the pipe geometry can be assumed negligible. While the pipe geometry in a flow lab usually is known very accurately, it is very difficult to provide ideal flow conditions. Therefore it is desirable to find a method that allows for calibrating a Clamp-on flow meter independently of the pipe and the flow profile which are not part of the meter that is delivered to the measurement location. The aim of this project is to investigate the transferability of such a new calibration technology into the field. The meter formula of an ultrasonic flowmeter includes an acoustic calibration factor, a fluid mechanic calibration factor for the flow profile influence and a geometric calibration factor which is identical to the inner cross sectional area of the pipe. Whereas the acoustic calibration factor is part of the flowmeter, the other two factors belong to the measurement location in the field. The new calibration method determines the acoustic calibration factor directly and, thereby, enables the calibration of the clamp-on flow meter independently of the pipe. It also enables to replace or recalibrate transducers at any time after the initial installation without the need to recalibrate the meter. This paper covers the results of research cooperation, over three years, between the Physikalisch-Technische Bundesanstalt (PTB) and Flexim GmbH (FLX). The aim of this cooperation was to investigate the transferability of the new calibration technology for ultrasonic clamp-on flowmeters into the field. Quantifying the transferability requires providing field conditions in a flow lab while keeping the uncertainty of the flow profile influences and the pipe geometry substantially lower than the uncertainty of the acoustic calibration factor. Such conditions can be provided by the hydrodynamic test field (HTF) of PTB in Braunschweig. The HTF is the German national standard of the volume and flow-rate measurements of liquids. It is operated with the fluid "water" in a flowrate range from 0.3 m3/h to 2100 m3/h and with an expanded relative measurement uncertainty of 0.02 %. The investigations were conducted on three pipes with 50mm, 100mm and 300mm nominal pipe diameter. The fluid mechanic calibration factor, in this project, was determined from the flow profile measured by means of a Laser Doppler anemometer (LDA). |
