A method for using ‘hot film’ anemometers to determine circulation velocities within vacuum pans has been refined and tested on a number of pans during trials performed over the 2001 season. The anemometers have been used to characterise circulation velocity profiles that can be used to validate computer models and illustrate the differences among pan geometries. The method has also been used to show the effects of adding pan boiling aids and to examine the effect of changing operating parameters. The method has been shown to be effective in producing reproducible velocity profiles within vacuum pans. The values for circulation velocities obtained are considered reasonable and there are promising indications of the ability to use this technique as a qualitative tool to investigate the causes of poor circulation and the effects of varying
operating parameters.