The calibration facility in Suzhou, China, is setting new standards: It can even calibrate flowmeters with very high nominal widths – fully automated and with the highest precision. The certificates are valid worldwide.
The gray stainless steel pipe is taller than a human and almost spans the entire length of the 76-meter-long hall. One of the pipeline’s segments is blue: it’s an electromagnetic flowmeter with a large nominal width that is currently undergoing calibration. A steady, gentle whirr can be heard; now and again an employee looks at a display to check that everything is in order. Suzhou is one of Endress+Hauser’s international production sites. Magmeters of the Proline Promag type with large nominal diameters are manufactured to customer specification at the new plant – the third in Suzhou. Afterwards, they are immediately calibrated and adjusted so that they will later provide precise measured values for the customer.
Endress+Hauser guarantees a maximum deviation of 0.2 percent from the measured value. The calibration facility itself works three times as precisely: “At 0.666 percent, the uncertainty in measurement corresponds to a glass of champagne in a full bathtub,” says Project Manager Jürg Gfeller. He managed and accompanied the construction and start-up of the Suzhou calibration facility for Endress+Hauser Flowtec, the Group’s competence center for flow measurement technology. The mechanical engineer was present on site for over 200 days. It’s no coincidence that the new facility is in China. The country is rapidly developing its water supply, which creates high demand for flow measurement devices with large nominal diameters. Endress+Hauser has successfully established itself in this growth market over recent years with its high-precision flow measurement technology.
The new calibration facility has a total of four measurement sections, three of which are designed for fixed nominal widths (DN) of 1,400, 1,600 and 1,800 millimeters. The fourth can be modified to between DN 2,000 and DN 2,400. Even a nominal width of 3,000 is set to be implemented by the end of 2018 – a new record in Endress+Hauser’s production network; until now, DN 2,400 in the facility in Cernay, France, was the maximum. Before its official start-up, the new facility was given JSMI approval by the relevant Chinese authorities; meanwhile an accreditation in accordance with the international standard ISO 17025 has been applied for from the national CNAS accreditation service. Flowmeters that aren’t destined for the Chinese market can therefore also be calibrated in Suzhou and employed all over the world. “Our customers can be certain that their measurement devices are globally compliant, no matter where they were produced,” emphasizes Jürg Gfeller.
One of the special features of the Suzhou plant is its construction as a closed system. The water is circulated by pumps at a constant pressure, flowing through the test piece and the reference instruments, referred to as masters. “This setup allows us to run measurements for any length of time. We can therefore guarantee stable, reproducible conditions,” says Jürg Gfeller, describing the concept’s main advantages. Fourteen Coriolis instruments of the Promass X type serve as the calibration standard. These are connected depending on the flow. Due to the high-precision Coriolis principle, its measurement inaccuracy is at least four times lower than that of the electromagnetic test pieces.
Metrological traceability is an important requirement for the global validity of the calibration results. This principle applies to all Endress+Hauser’s flow calibration plants around the world. It stipulates that every measurement device was calibrated at a precise facility, which was calibrated at an even more precise facility, and so on – up until international standards such as the primary kilogram in Paris as the ultimate reference.The Coriolis masters in Suzhou are therefore accordingly calibrated individually at regular intervals. This is done by calibrating the measured values with a scale, which is in turn calibrated using calibrated weights which are audited by an accredited laboratory in China every two years. “The calibration of the test pieces as well as the traceability leading up to the standard weights is fully automated,” says Jürg Gfeller. “This can be found in no other calibration facility in the world.”