Does ageing influence the gas capacity of a canister?
About TNO Independent research organisation Located in The Netherlands 5000 people Turn over 570 M 5 core areas Defence, Security and Safety BU Chemical and Biological Protection Research group Threat and Protection
The question Dutch Ministry of Defense Over 200 K canisters on stock LOT ends Can we still use them? Does artificial ageing represent actual storage? What causes a decrease in capacity, if any?
Measurement program Measure breakthrough time of new canisters and carbons Store carbon and canisters under various conditions OR perform artificial ageing procedure Measure breakthrough time again to identify a possible decrease in adsorption capacity CBRN canisters: ClCN and chloropicrin (CCl 3 NO 2 ) ABEK canisters: SO 2 and NH 3 Chemisorption (ClCN, SO 2, NH 3 ) and physisorption (chloropicrin) Requirements according to NATO and European standards
Test equipment air toxic component detector RH / T air exhaust m ix canister or carbon flow meter water
Breakthrough time critical conc. effluent conc. breakthrough time time (min) The longer the breakthrough time, the larger the gas adsorption capacity of the canister or carbon bed
Storage conditions hot-cold outside inside alternating 1 month at -30ºC, 1 month at +40ºC outside air temperature, between -10ºC and +30ºC room temperature of (25 ± 5)ºC Samples were stored in their original packaging
Storage effect on CBRN canister: chloropicrin breakthrough time (min) 50 40 30 20 10 Storage conditions hot-cold outside inside 0 0 6 12 18 24 30 36 storage (months)
Storage effect on CBRN canister: chlorocyan breakthrough time (min) 40 30 20 10 Storage conditions hot-cold outside inside 0 0 6 12 18 24 30 36 storage (months)
Storage effect on ABEK2 canister: NH 3 breakthrough time (min) 100 90 80 70 60 50 40 30 20 10 0 0 12 24 36 48 60 storage (months) Storage conditions hot-cold outside inside
Storage effect on ABEK2 canister: SO 2 breakthrough time (min) 40 30 20 10 Storage conditions hot-cold outside inside 0 0 12 24 36 48 60 72 storage (months)
Artificial ageing Only known for CBRN canisters Several different methods (NATO, US/UK standards) Most of them: equilibrate the carbon at 80% RH store open to the air at elevated T and 80% RH measure ClCN breakthrough time Criterion to pass test is either a required minimum value or 50-80% of the required unaged value
Artificial ageing effect on CBRN carbon: chlorocyan breakthrough time (min) 25 20 15 10 5 Conditioning at 90 ºC / 80% RH 45 ºC / 80% RH 23 ºC / 80% RH 0 0 2 4 6 8 10 conditioning time (days)
Artificial ageing effect on CBRN carbon: chloropicrin breakthrough time (min) 35 30 25 20 15 10 5 Conditioning at 90 ºC / 80% RH 45 ºC / 80% RH 23 ºC / 80% RH 0 0 2 4 6 8 10 conditioning time (days)
Surface structure of impregnated activated carbon Two carbon rods x70 Fracture surface of carbon rod x120 Experiments performed by A. H. J. van den Berg and M. A. Smithers, CMA lab, MESA+ Institute, University of Twente, Enschede
Clustering of metal salts within activated carbon Fracture surface of activated carbon rod impregnated with metal salts x2000 x15000 Experiments performed by A. H. J. van den Berg and M. A. Smithers, CMA lab, MESA+ Institute, University of Twente, Enschede
Surface composition of an impregnated activated carbon Atom % of elements at rod fracture C 60-80 O 15-25 Cu 2-5 Cr 2-4 Mg ~1 K ~1 N 1-1.5 S ~0.1 Ca ~1 CuO, Cu(OH) 2, CuCO 3, Cu 2 CO 3 (OH) 2, CuCrO 4 CrO 3, Cr 2 O 3, CrO 2, CrCuO 2, Cr(OH)O, Cr(OH) 3, CrO x MgO, Mg(OH) 2 Experiments performed by A. H. J. van den Berg and M. A. Smithers, CMA lab, MESA+ Institute, University of Twente, Enschede
Conclusions Ageing up to 3 years hardly influences the gas capacity of a canister Follow-up experiments will be performed The canisters and carbons tested can still be used by the Dutch MoD Artificial ageing might represent actual storage More research is needed The surface structure of aged carbon is similar to that of new carbon
Thank you for your attention! Questions? SUGGESTIONS? remarks? CRITICS? ANYTHING NOT CLEAR?