We are beginning to plan a set of lab based experiments with our three current hydrogen sulfide sensing projects: the photographic paper assay, the copper pipe recently described by TXsharon and the digital sensor:
Notes for our experiment set up:
Factors for consideration:
Any reactive metal in the testing container or in the gas circulation system will absorb some of the H2S as the H2S will react with the metal. Therefore it is important to limit the amount of metal exposure--hence the use of a perspex box in Horwell et. al. We will need a gauge in the experimental set up to ensure the correct internal concentration.
H2S is hazardous and smelly so we need to ensure there are no leaks and we will know quickly if there are leaks.
To compress the air we can borrow an air compressor from Roy, it makes noise as it is compressing--so we will need to alert others in the area before we begin an experiment.
The system will need to be stable enough to run for multiple days, so we need to ensure continual power to everything, quantity of gases before hand etc...
A canister of mixed H2S gas may cost $1000. However one canister at 1000 ppm will probably be sufficient for all of our experiments.
Running the resulting gas through a charcoal filter will absorb the excess h2s and remove smell.
Multiple days of continuous exposure may not adequately represent field conditions for gas patch exposures. We should gather data on current gas patch exposures such as when/where does the smell occur and how long does it last? Record temperature/humidity. Then we could model our experimental design on those exposure conditions. Perhaps we might want to try blasting the strips with short bursts of high concentrations? Rather than long continuous exposures?
We should look in to concentration of H2S that can be expected to be found in sour gas.
Should we use purified air? Roy felt since we know there is little to no H2S in air as the noses are so sensitive to it, there is no need to use purified air as Horwell et. al. did.