A review of the impact of component variation in the manufacturing process on variable area (VA) flowmeter performance

Abstract

The quality of an instrument, and thus its ultimate accuracy, will clearly be critically affected by the nature of the manufacturing process. Following a brief description of the variable area (VA) meter, the production process of one manufacturer is examined. The manufacture of the float, tube, scale, the calibration of the instruments, and the computer systems for logging the production progress of each instrument are briefly considered. The equation of the VA meter can be analysed to determine the effect of component variation on the meter's accuracy, and the details of this calculation are given in Appendix A. The values used for variation have been estimated to reflect the likely situation in the industry. The most common problems and the possible areas for future work on the development of these valuable instruments are reviewed. Finally, more general lessons have been drawn for instrument manufacture from this example.