The StackFlow II utilises an advanced Electrodynamic cross correlation technique to accurately determine particle and hence stack velocity. The instrument accurately measures the electrical signal induced by particles passing a sensor rod. This signal is cross correlated with the signal derived from a second downstream rod to determine the transit time of the particles. The velocity is simultaneously calculated since the geometric spacing of the sensor rods is known.

Unlike most other velocity techniques the response of the instrument is not impaired by the presence of particles. This means the StackFlow II can provide robustoperation in particle laden and aggressive applications. The instruments pre-set calibration is sufficient for most stacks less than 4m in diameter*.

Site calibration (for example against a pitot traverse) is only required in stacks with non-uniform velocity profiles.

*Assumes relatively homogenous flow.