A model of the flow characterlstlcs of a simple smgle-lme flow-mJectlon mamfold 1s described and evaluated for the effects of various operating condltlons on peak parameters, m particular peak height The model 1s based on the mechamsm for dispersion of dlffislon across concentration grachents generated by lammar flow m a closed circular pipe The flow conduit 1s considered to be drvlded mto a number of segments both racbally and longitudmally The number of the segments m both dlmenslons IS calculated from an empnIcally derived relatlonstup from the mltlal input parameters of length, internal diameter, sample volume, detector volume and flow-rate An lteratwe procedure assigns whole number values to the number of segments Both normal and reverse procedures can be modelled Diffusion IS modelled by averaging the concentration of any one segment over those with which It has a common boundary and flow by transport of a proportion of the contents of a segment according to a parabohc velocity prohle The performance of the model was evaluated from the predicted peak heights for manifolds m which Injector volume, flow-rate and tube length were varied The predicted effect of changmg the volume of the detector was examined The model Indicates that detector volume has little effect on peak shape unless the mjected volume 1s less than the detector volume Keywords Flow system, Peak height predlctlon, Sample transport