Fuel Gas Scrubber is part of the Gas Sweetening unit which functions to separate the heavy fraction (liquid) that is contained in the hydrocarbon mixture gas. The efficiency of the scrubber unit's performance in separating the liquid content carried by the gas stream cannot reach 90% if the particle size (liquid) separated is less than 25 µm. Currently, the deviation of the liquid content contained in the top product of the Fuel Gas Scrubber cannot be detected in real-time. Therefore, a method is needed to model the gas impurities produced by the Fuel Gas Scrubber through the correlation of process variables. Mathematical models are used to verify the most influential process variables through statistical correlation tests. Top product quality mathematical model with verified parameter correlation, used to verify process loop of Fuel Gas Scrubber based on Piping and Instrument Diagram Process. From the experiments that have been carried out, the Ordinary Least Square method is the most capable method to producing a good estimator value. The average error of the model obtained is 4.42%. In addition, this model can be used as a guide to improving the performance of the Fuel Gas Scrubber 141-V-01, by making improvements to the four process loop parameters that have the most significant effect on the top product quality, namely, level indicator, pressure indicator, pressure transmitter, and level transmitter.