The metrology takes an essential place in today’s industrialised world. Measuring in real time the exact flows consumed by different processes is critical. Whether measuring gas, water, fuel etc., even the slightest measurement error could have a negative impact on safety, quality and the financial equilibrium of the entire production chain or even the viability of a technical project. Therefore, it is crucial to use accurate and reliable fluid measurement instruments along with adequate calibration methods. The combination of clients’ needs and the type of calibrated device constitutes a set of constraints which guides the choice of the calibration method to be used.
Trescal is a global major player in industrial metrology. The flow laboratory of Trescal/Cherbourg is one of the four most important accredited laboratories in France.
The company is involved in the flow measuring business through the calibration of volumetric and mass flow meters used in many sectors, such as aeronautics for fuel supply flows, nuclear for cooling circuit flows or sealing of buildings, the food industry for the precise measurement of culinary recipes, pharmaceutical industry for measuring the quantities of molecules to be mixed or even in electronics for the production of printed circuit boards.
Fundamental calibration method
The Liquid Flow laboratory of Trescal Cherbourg is accredited by COFRAC since 1993. The accreditation covers volume flow over the range from 10 l/h to 35000 l/h following the method by Gauging issued from an international standard “Method by collection the liquid in a volumetric tank ” reference ISO 8316; achieving uncertainties of 1.1 x 10-3 to 9.0 x 10-4 of the flow rate.
For clients who need very low calibration uncertainties, this method is ideal; however, to achieve that, more time is required. The time for one flow measurement point may vary between 4 to 48 hours depending on the flow rate.
The advantage of this calibration system is that there is great flexibility on its setting up, allowing connections with maximum diameter of 50 mm.
- Variable section
Development and client’s needs:
Time, Quality and Price are often the main concern for both Trescal and its clients. The calibration time costs money, in some cases it seems that the calibration price has a higher cost than the price of the calibrated device itself. After an analysis of the clients’ needs, we found that the required tolerance is approximately 1,0.%Qv of the flow rate. To better meet the expectations of our clients’, the growing demands and high utilisation of our liquid flow laboratory, TRESCAL has developed an alternative method with slightly increased uncertainty of calibration. This method is very cost effective, valid and has been operational since March-2019. It has considerably increased our efficiency and productivity with typically 75% time savings and meets customer expectations and deadlines.
The Alternative Calibration method: by comparison to Coriolis flowmeters
The alternative method is based on comparing the clients device to a reference flowmeter. Two Coriolis flowmeters were selected as reference standards because of their good stability and repeatability. They covers the range from 10 l/h to 35000 l/h. These reference standards are calibrated using the fundamental method in the laboratory. This alternative method offers uncertainties of 3.0 x 10-3 to 4.5 x 10-3 of the flow rate which is circa of 3 times greater than the uncertainty of the fundamental method, although with the advantage of reducing significantly the calibration time (100 sec/point) being 3 to 6 times faster.
- Following numerous requests from our clients, we intend to extend the accreditation in mass flow.
- As the alternative method meets more than 30% of our clients’ requirements for accredited calibration, our goal is to apply the accreditation using the direct comparison of Coriolis flow meters from 10 l/h to 35,000 l/h in the first half of 2020. This approach will improve our productivity significantly.
- Roll out this new alternative method in the customer sites.