Anti-contamination calibration method for ultra-fine dry chemical agent: Achieving wide measurement range and high measurement accuracy

Achieving real-time measurements of ultra-fine dry chemical agents (UDCA) is extremely challenging, with their complex composition, high injection concentrations, and susceptibility to contamination. In this study, a high-concentration particulate matter measurement method was proposed based on the extinction principle to reduce the powder contamination effect during calibrations. Through theoretical analysis and experimental verification, a functional relationship was established. Calibration experiments were conducted using sodium bicarbonate (SBA) and potassium bicarbonate (PBA) UDCAs, which are the most representative. The results showed that the measurement ranges of SBA and PBA reached 227.15 g/m3 and 122.55 g/m3, respectively. Compared with the uncorrected calibration method, the maximum indicated errors of SBA and PBA with the powder contamination effect corrected were reduced from 11.25% and 22.68% to 5.98% and 9.21%. This method provides a strategy for measuring high concentration powder, especially for achieving the measurement of UDCA in aircraft engine compartments.