Speed governing Proportional control

Proportional-action governor is a governor with inherent regulation and a continuous hnear relation between the input (speed change) and the output of the final control element, the governing valve. 

Either the rate of diffusion to the surface or the speed of the surface reaction governs the rate of removal of the gas from the air stream, depending on which is the slower process. If k is dependent on flow rate, then diffusion is the rate-governing step. From Table XII it is evident that k is proportional to L. Therefore, one can assume that mass transfer is the rate-controlling step and the surface reaction is much faster than the diffusion process. 

Analyte/matrix considerations and sample types Since both the transport of analytes from the matrix to the bulk fluid (removal) and the transport of analytes from the extraction cell to the collection device (elution) govern the extraction process, but to different extents for different analyte/matrix combinations, attempts have been made to classify samples. Two extreme groups of sample types can be identified based on flow rate studies those were the analytes are recovered at a rate proportional to the fluid flow through the extraction cell, and those completely unaffected by the flow rate. In the former group of samples, the elution of the analytes is controlling the extraction speed, while in the latter group of samples, analyte removal is limiting the overall extraction procedure. 

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