38-11

M. P. HINTERREITER, Enhanced Density Intern / Student at Univ of Colo at Denver, Micro Motion, Inc., 7070 Winchester Cir, Boulder, CO 80301 and R. V. Kovacs, Software Engineering, Micro Motion, Inc.

Measuring Alcohol Concentration is an exact science. Many companies, organizations, and governments depend on precise measurements for process control (recipes) or taxation purposes. Using a Coriolis multiple variable sensor: which measures mass flow, density, and temperature, it is now possible to measure gross flow, net alcohol flow, and alcohol concentration in an inline continuous process. The Organisation Internationale De Metrologie Legale (OIML) tables were utilized as a baseline set of acceptable data. This data set includes alcohol volumetric concentration as well as 7 other tables of concentration data, and the coefficients and equations for calculating some of the tabular data. It takes significant processing time to calculate the entire range of alcohol concentration in the OIML tables, a smaller user defined range can be calculated with a much simpler algorithm. Given a range of density, concentration, and temperature points, a 4th order linear regression is performed in two directions over the data to calculate a density at reference temperature curve. Performing another 4th order linear regression over the density at reference temperature the data is converted to volumetric concentration. The user data range is then calculated using the derived coefficients and polynomial expansion. This data created from the reduced set of coefficients is compared against the original equations to calculate the mathematical residuals. 3-sigma sensor accuracy is then determined by the combination of density measurement, temperature measurement, and mathematical residual errors. Entering the data into the sensor’s computer allows a final verification; the coefficients are recalculated to a single precision floating point (7 digits), and the concentration calculation is performed in the sensor. After verification the unit is ready for use measuring the % Volume of Alcohol in a given application with known accuracy. Testing results from numerous sites around the world and field performance data is presented.