Non-destructive method for determining the residual holding capacity of an adsorbent filter and associated test bench

A non-destructive method for determining the residual filtration capacity of an adsorbent filter of a given type, the adsorbent filter being apt to adsorb a target gas, characterized in that the method comprises the following steps:

• (a) selecting a probe gas and a carrier gas apt to cross through an adsorbent filter of the given type, unsaturated with target gas without remaining trapped therein, the probe gas having an adsorption isotherm such that at a partial pressure of 0.1 atmosphere of the probe gas, the adsorption isotherm has an adsorption capacity of less than 100 μmol of probe gas per gram of adsorbent, the probe gas being intended for being mixed with the carrier gas, for being injected into the adsorbent filter of the given type,
• (b) at a given operating temperature, pressure and hygrometry, selecting parameters for the injection of probe gas and carrier gas into an adsorbent filter of the given type, the injection parameters comprising, for the probe gas and the carrier gas, a given period and a flow-rate over time curve, the concentration of the probe gas in the carrier gas including at least one sudden variation during the injection period, each sudden variation in the concentration of the probe gas with regard to the injection parameters of the probe gas being characterized by an absolute value of the time derivative of the concentration of the probe gas, which exceeds 100 ppmv/s,
• for an adsorbent filter of the given type, called reference filter,
• (c) injecting, at the given operating temperature, pressure and hygrometry, the probe gas and the carrier gas into the reference filter according to the injection parameters of the step (b) and measuring the change over time in the concentration of the probe gas, downstream of the reference filter for known increasing amounts of target gas adsorbed by the reference filter, the latter of such quantities corresponding to the breakdown of the reference filter, and deducing the filtration capacity ma of the reference filter,
• for an adsorbent filter of the given type for which the residual filtration capacity is to be determined, called filter under test,
• (d) injecting, at the given operating temperature, pressure and hygrometry, the probe gas and the carrier gas into the filter under test according to the injection parameters of the step (b) and measuring the change over time in the concentration of the probe gas;
• downstream of the filter under test,
• (e) comparing the change over time of the concentration of the probe gas for the filter under test and for the reference filter, for determining a saturation value of the filter under test τsft, and
• (f) deducing the residual filtration capacity of the filter under test by the following calculation:
• residual filtration capacity=(1−τsft)*ma.