Application Corner: Flowmeter billing errors, part 2

In a previous Application Corner column, a legal case with potentially large steam billing errors due to potential measurement errors associated with the boiler steam flowmeters was discussed. Interestingly, did you know that the flowmeters had not been calibrated during the previous seven years? Why, you might ask? The primary reason was that plant personnel started to refuse to work with instruments that contained mercury, like these flowmeters, approximately seven years prior.

The lack of calibration during a long period of time caused the steam provider to claim that the steam flowmeters were not accurate. By the time the steam purchaser hired me as their flow measurement expert, at least two engineers (who worked for the steam provider) had already spent months performing a plant-wide steam study encompassing hundreds of pieces of equipment to back-calculate the amount of steam produced by the boilers. My objective was to assess the accuracy of these high-pressure, high-temperature steam flowmeters that had not been examined internally since installation 50 years prior and that had not been calibrated for seven years.

The academic approach to this problem would be to inspect the flowmeter internals and calibrate the flow transmitter. This was not possible because the flowmeters could not be taken out of service and the plant refused to calibrate flow transmitters containing mercury.

The next best approach was to compare these flow measurements with other plant data. However, legal restrictions limited the information that could be requested and reasonably obtained.  

David W. Spitzer is a principal at Spitzer and Boyes, LLC, which offers engineering, focused market research, writing/editing white papers, strategic marketing consulting, distribution consulting, seminars and expert witness services for manufacturing and automation companies. Spitzer has written more than 400 technical articles and 10 books about flow measurement, instrumentation and process control. He can be reached at 845-623-1830 or via spitzerandboyes.com.