pescador775
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I did some calcs but all my assumptions are hypothetical. FWIW, I suggest that a tank which is being filled from a common compressor be cleaned at a time between 25-100 fills, eg, for purposes of PP mixing.
Assuming that one milligram oil/hydrocarbon is deposited in the tank per fill and assuming that the threshold of safety is one drop (25 mg) of oil/hydrocarbon, the limit of safety is 25 fills. Thus, clean the tank after 25 fills.
I don't know if this is supportable by any studies or experiment but anecdotal evidence suggests that it is conservative. Lots of guys have PP filled and topped off with common compressors using the PO and similar filters which some people like to hate. Mostly, these are the shamans of the diving community who incant spells while waving invoices for $1500 filter canisters.
The 25 mg oil would likely be accompanied by 20 X that much water and the presence of water which does not support combustion particularly well should extend the proposed cleaning cycle up to 100 fills or thereabouts.
Although Grade E has an allowable limit of 5mg/m3 oil I believe this is obsolete. When the moisture limit spec'ed under grade E was dropped the oil limit was not. This ignores the fact that methods currently used to reduce moisture to 24 ppm (v) also scrub oil more efficiently.
Assuming that one milligram oil/hydrocarbon is deposited in the tank per fill and assuming that the threshold of safety is one drop (25 mg) of oil/hydrocarbon, the limit of safety is 25 fills. Thus, clean the tank after 25 fills.
I don't know if this is supportable by any studies or experiment but anecdotal evidence suggests that it is conservative. Lots of guys have PP filled and topped off with common compressors using the PO and similar filters which some people like to hate. Mostly, these are the shamans of the diving community who incant spells while waving invoices for $1500 filter canisters.
The 25 mg oil would likely be accompanied by 20 X that much water and the presence of water which does not support combustion particularly well should extend the proposed cleaning cycle up to 100 fills or thereabouts.
Although Grade E has an allowable limit of 5mg/m3 oil I believe this is obsolete. When the moisture limit spec'ed under grade E was dropped the oil limit was not. This ignores the fact that methods currently used to reduce moisture to 24 ppm (v) also scrub oil more efficiently.