Whenever finned—tubed cooling bundles are arranged in parallel, as shown in figure 5-2, a potential exists for poor cooling due to gas maldistribution. A low gas outlet temperature from an individual bundle is indicative of lack of gas flow through that bundle. To correct this situation, measure the total pressure drop across the coolers. Next, install restriction orifices in the inlet of each bundle, with openings calculated to double the observed pressure drop. This should bring the outlet temperatures from each bundle reasonably close together. If not, take the tube bundle with the low gas outlet temperature off-line for hydro-blasting of the tube side.