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Is anyone aware of a sizing criteria/procedure for vents in tanks/vessels that handles fine powders?

I am currently reviewing one vendor's proposal for a given conditioning package aimed to inject certain chemical aqueous solution into the main process.

The chemical (fine powder form) comes in bags that are emptied via manholes into one mixing vessel in which water is subsequently ingressed in order to prepare the solution. The vendor drawings shows this vessel's vents ("goose-neck"-type) to be 1" in diameter. I am concerned about long term clogging of such small vents due to progressive accumulation/compaction of powder fines in them (the fact that the vents are open to atmosphere and that water condensation will occur at times -minimum ambient temperature= 15 degrees C- makes the concern stronger).

I have checked vents size against results obtained from equations in the API 2000 RP. Although on these grounds the vents seem to be of adequate size the long-term clogging concern remains as the impact of fine powders is not especifically addressed by API.

From the back of my mind, I remember once reading somewhere about specific guidelines for sizing vents on powder services. Yet memory fails to bring further details.

Is anyone aware of a specific sizing criteria/procedure applicable to vents in powder services?

Thanks for everything.