Automated Weighing of PM Filters: Impact of Equilibration Duration

Abstract

This study aims to present results from the repeated measurements of unloaded PM filter mass using the robotic weighing system RB 2.4Y.F, (Radwag, Poland) and to select the most appropriate equilibration time.The criteria for filter equilibration used in this study followed the PN-EN 12341:2024 standard.For that purpose filters of different types (quartz-QF, glass-GF, nylon-N, Teflon-PTFE, and polycarbonate-PC) were equilibrated in a controlled atmosphere, and weighed in replicates for nearly two weeks in the case of quartz fibre filters and for over a month in case of other filters to check the effect of conditioning time on filters mass deviations.This study aimed to compare mass deviations among filters along with increasing conditioning time and, consequently, determine the choice among acceptable filters based on mass stabilization criteria.As a standard, 9 successive filter weighing cycles were performed, except for quartz filters for which 3 weighing cycles were carried out.Based on the obtained results, the average mass of the unloaded quartz filters remains stable throughout the conditioning time while maintaining constant relative humidity (50 5%) and air temperature (20 1C).Similar results were observed in the case of glass fibre filters.The weight of Teflon and polycarbonate filters stabilized much longer (in the 4th and 6th weighing cycles, respectively), and it was higher by more than 1 mg than the initial weighing.The reason for the longer stabilization time compared to quartz or glass fibre filters was most likely the absorption of electrostatic charges on the surface of Teflon and polycarbonate filters, caused by the ineffective operation of the deionization gate.