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Abstract

Manufacturers of fans and ventilators use special fan test rigs during research and development and as end-of-line test benches for the production facilities. There are many kinds of constructions available, which are harmonized by standards like DIN EN 5801 and AMCA. Nevertheless, have you ever asked yourself the critical question: Can we believe the results? How valid are the measured values actually? Are the results of our different test equipment at different locations comparable?
The only thing that can give you security is a so-called transfer standard.
We provide an overview of the calibration pyramid: from the fan itself, over the working standard fan test rig, the transfer standards and primary standards up to the SI units of length and time. To ensure security about your data, complete traceability back to the SI units is essential. The transfer standard can be used by a calibration laboratory or by a manufacturer himself. The transfer standard is connected to the fan test rig and does not calibrate the fan, but the test rig. It closes the gap between working standard and primary standard in order to achieve full traceability.
We show all the criteria that must be met by a volume flow measurement system in order to work as a good transfer standard. In a concrete example project, we present a transfer standard covering a flow rate from 4 to 40 000 m³/h, which serves as a basis for the worldwide comparison of test stands of a well-know fan manufacturer both for test stands in blowing and suction operation. In order to cover a measurement range of 1:10 000, we have combined different measurement sections in one flow measurement system. Depending on the flow range that it to be covered by the transfer standard, different types of measurement sections can be advantageous. We take an overview of the advantages and disadvantages of different measuring sections. In addition, we focus on the measurement accuracy, the calibration process of the transfer standard itself and the calibration process of the test equipment with the transfer standard, as well as the ease of use and mobility of the system.