Vent Requirements
Vent Requirements
(OP)
Do dust collectors located outside of buildings require vent protection per NFPA 68? If so, what paragraph in the NFPA 68 Standard references this requirement? Thank you!
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RE: Vent Requirements
RE: Vent Requirements
Thanks for your response. I have the same understanding from the NFPA Standard.
Does the owner accept the risk or the AHJ? It seems to me that the AHJ would never accept any risk for loss of equipment or any possible safety risk.
Do you have any feel for industry standards on explosion venting (such as Kst or Pmax values) on dust collectors or material separators located outdoors?
Would silo's having combustible dust fall under this risk option also?
Thanks for any help.
RE: Vent Requirements
RE: Vent Requirements
I've vented silos, and the more elongation the worse it becomes. I've also proven to maintain less than the LEL, proven and the owner accept the risk.
All conditions and dust/particle size differ. There is no cut and dry.
Combustible dust is getting a LOT of attention currently, and I would NOT cut corners.
RE: Vent Requirements
NFPA says, all combustible dust enclosures should be located outdoors. If they are indoors they should have vent protection as per the standard. It "NFPA" does not say combustible dust enclosures outdoors need venting as well.
The materials can vary but the ranges for Kst are between 100 and 210 bar m/sec.
Is the required venting area equation and calculation in NFPA 68 2007 different then the required area for venting that may have been made by the previous NFPA 68 edition?
Good point on the EPA requirements. I have them covered.
RE: Vent Requirements
You will most likely take the complete roof as in a API 650 application of "frangible roof seam", but with your much smaller diameter angle rings/welds must be reduced in size.
There was a very good study, write-up, and computer application written by a group from a Oklahoma University on frangible roofs of tanks less than 50-feet in diameter out on the 'net. I think it was called "saferoof".
I've also taken the upper portion of the cylindrical shell and placed multiple vents around the circumference above the maximum level. This was when I had excess weight on top.
RE: Vent Requirements
RE: Vent Requirements
Would it be fair to compare the new calcualted vent area vs an existing vent area that may have been installed many years ago?
Thanks!
RE: Vent Requirements
You are NOT required to resize the vent on older installations until an equipment change, process or explosivity change requires it (I think I am correct here, because the older methods were more conservative). There are required changes in documentation, procedures, etc.
The client I work for has 30+ explosion vented collectors, bins, etc. Its been decided to bring them all up to current standards as the old documentation is sketchy and with the growing emphasis on dust, we want all our ducks in a row.
RE: Vent Requirements
Good chat and I appreciate the help.