Time for sulfurs!
The Standard Test Method for Sulfur Compounds in Light Petroleum Liquids by Gas Chromatography and Sulfur Selective Detection (ASTM D5623), which we commonly refer to as a speciated sulfur analysis, necessitates an additional detector equipped in the GC (flame photometric) and can, theoretically, resolve any sulfurs in the gas (the ones @GasGuy-QEG listed above are those of greatest concern).
Generally, if sulfurs are tested at all, it’s done via a total sulfur sulfur analysis (ASTM D6667). For our remediation methods, we need to see exactly which sulfurs and at which concentrations they may be present. We also enjoy having the ability to distinguish sulfurs to determine whether the truck was properly cleaned between loads as we require. (E.g. If we tested a load of high purity propane and found it to have hydrogen sulfide present, we would suspect it to be contamination from a prior load of y-grade product and be able to refuse delivery based on such analysis). However, a total sulfur analysis should be sufficient if remediation is not needed.
A sniff test may be sufficient to verify such an analysis but I think what we’re trying to get at here is the threshold level for what is acceptable for this application. Given that these sulfurs have varying, but all low, odor thresholds (list below) and considering that there is a potential for those odorous sulfurs to be concentrated in our customer’s final product, I would think that threshold should be extremely low, if not 0.000 ppmw. And I would certainly think we can safely assume that sulfur testing is warranted regardless of whether there’s a detectable odor in the gas.
Various sulfur odor thresholds (in ppmv):
Hydrogen sulfide, 0.00047
Dimethyl sulfide, 0.0010
Ethyl mercaptan, 0.0010
Sulfur dichloride, 0.0010
Benzyl sulfide, 0.0021
Methyl mercaptan, 0.0021
Hydrogen sulfide, 0.0047
Diphenyl sulfide, 0.0047
Carbon disulfide, 0.21
Sulfur dioxide, 0.47
Any input from extractors on what an acceptable level, if any, may be for sulfurs?