As a dedusting equipment, Bag Filter 432-BF1 was designed in such a way to process dust derrived from the raw meal transport process in kiln feeding area in order not to cause air polution and not disturb the work of the equipment that is directly related to the process flow. PT Holcim Indonesia Cilacap Plant targets low polution, so bag filter must work by optimum. Differential pressure (DP) is a parameter that acts as an indicator of the performance of bag filter itself. The value of the differential pressure which is more than 150 mmH2O indicates an abnormal condition of the bag filter. Weekly inspection of Maintenance Department from 2016 to 2018 shows that the differential pressure of Bag Filter 432-BF1 is more than 150 mmH2O. In the latest two years, Bag Filter 432-BF1 has trouble in its operation. The filter bags cannot perfectly collect the dust particles because of the coating of dust particles in a specific quantity that is not falling off during the purging system. That remaining dust particles disturb the effectiveness of the purging system. This phenomenon occurs because the existing purging pipes are not big enough to flow the total purging air that is needed during the purging process. This can be said that there is deviation between the actual purging flow and the purging flow based on the manual book. The purging shot is spreaded in all directions since there is no dirrectional tube. The modification which is going to be done is replacing the purging pipes which are already installed with the new ones that have bigger diameter and adding directional tubes. Larger purging pipes are expected to aim more flow to filter cage, and the directional tubes are expected to make the purging shot is directed to filter cage. By carrying out this modification, the trouble of coating that often happens on bag filter 432-BF1 can be solved.