Automated Calibration Test Stand for Volume Flowmeters
Following the conception of Aquametro one of the most modern automated series oil calibration test stands in Europe was developed. The precision test stand (working standard for oval wheel meters 0.06%, control containers 0.0125%) is used for the calibration and gauging of Volume Flowmeters. The plant was implemented by Bopp&Reuther Messtechnik GmbH (Plant Systems) and ICS GmbH (Automation and Control Software).
Target of the new investment was to provide automated calibration test stands for up to 10 test objects of each operation for a very wide flow range. To enbale testing of test objects with nominal ranges of DN15 to DN50 with a flowrate of 10 to 30.000 l/h four master meters of different measuring ranges were used which were selected automatically depending on the type of the test objects. A particularly fast and accurate impulse entry is achieved by using the double stopwatch method according to ISO 7278/3. In addition, the pressure and temperature of the test oil are measured in the test section.
Oval Wheel Meters by Bopp&Reuther are used as masters. The automation is implemented using a WindowsNT-PC with an integrated MSR-Card made by Sorcus. ICS GmbH individually adapted and developed the Automation and the configurable control software along the test bench requirements.
Following a very short start-up procedure which was, above all, based on smooth co-operation between Aquametro and their suppliers, the test bench has been in operation since July 2001 and meets all requirements. Very delightful is the high acceptance of the control software by the operating personnel.
Bopp & Reuther Oval Wheel Meters with high-resolution pulse pick-ups are used as masters. In order to cover a large measuring range with high accuracy, four masters with different nominal size are used in parallel. Over valves the test medium is led by the master most suitable in each case. Pressure and temperature of the test oil are measured at the master.
In the calibration of the masters calibration tanks are used as control substandards. The master calibration is executed semi-automatically.
The test runs were designed in such a flexible manner that permanent or in-process measurements were performed depending on the device type and situation.
The handling of the automation procedures and the control of the measurement is executed via a script-controlled automation manager. The script procedures define the control in detail. This methodology has the advantage that modifications are possible in the automation process without modifying the test stand software.
The test results are filed to an ACCESS-database thus ensuring continuous recording of the device properties. The design of the logs can be adapted to national and even to customized requirements by using a commerical report generator.
In the implementation of the operator routine special attention was paid to creating an ergonomic user interface. The overview provides the operator with complete information about the current status of the automatic test:
A zoom allows to display indivual values on request so that they can also be read from a larger distance.
The test results are displayed summarized in a graph or table to attain an efficient working method:
With electronic counters able to communicate the characteristic at the end of the check is stored immediately into the counters.