The fan pump propels the dilute slurry of papermaking furnish towards the headbox of a paper machine. The pumps are designed in such a way as to minimize pulsation, since the goal is to keep the basis weight constant over time and avoid “barring”. Thick stock, often having a consistency of about 3 to 5% is diluted with white water at the inlet of the fan pump. The consistency of thin-stock furnish coming out of the fan pump is typically between 0.3% and 1% solids. Papermakers often add chemicals such as fillers, acid, or base before the fan pump so that they can take advantage of the mixing action.Fan pumps are typically located in the basement underneath the forming section of the paper machine. Some paper machines employ two separate fan pumps so that it is possible to optimize the performance of hydrocyclone cleaners, with or without subsequent deaerating equipment.