Prediction of Filter Performances against Organic Vapours: Statistical Analysis of Breakthrough Times as a Basis for a Simple Prediction Model

The prediction of the protection efficiency of NBC-respiratory filters against organic vapours is often very difficult, especially when strong physical interactions or chemisorption processes are invoved. The presented statistical analysis is an attempt to develop a simple, but reliable, prediction model for breakthrough times. In over 70 experiments run under conditions of the EN 141 guidelines the breakthrough times of 39 organic compounds including alkanes, cyclo-alkanes, alkenes, alcohols, ketones and carboxylic acids have been measured for a given filter type. A linear regression model is then postulated to relate the breakthrough time to the adsorptive properties. For the model, each adsorptive molecule has been considered to be composed of a chemical functional group and a chain radical, resulting in a two dimensional structural code. The number of carbon atoms in the radical-chain and physical properties has been considered as an additional model parameter. General Linear Model (GLM) analysis was run to estimate model performances. We found out, that a simple linear model with only four regressors (two dimensional structural code, number of C atoms in the radical-chain and the saturation pressure) yields satisfactory breakthrough time predictions. Therefore, this study shows that, for a given filter type and well defined testing conditions, satisfactory predictions of breakthrough times of organic vapours are feasible.