We pull digested sludge out of anaerobic digesters and pump it into wells. The piping goes through a building that is about 400' away from the digesters. That building was classified by the engineering firm and approved by the county as unclassified. A worker asked me today why it isnt a classfied area. If a pipe broke in the bulding there would be digested sludge on the floor and some methane would most likely be present until valves were closed and the floor cleaned. There are drains and there is ventilation of 12 air changes per hour in the building. Any one have a good answer?
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Sludge piping in building = classified area? 2
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stookeyfpe
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The mere fact that a pipe that contains a constituent that dictates hazardous (classified) location electrical service does not always dictate area classification.
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Even a pipe full of only natural gas does not create a hazardous area. Pipes are not expected to leak, much less rupture. We don't classify areas based on catastrophic failure, or every boiler room would require explosion proof stuff. For a sewage pipe, or even a pressure pipe with hydrogen or gasoline in it, rupture is a catastrophic event.
Typically, a Zone 0 hazard exists when an explosive atmosphere is expected more than 1000 hours per year, and Zone 1 if over 10 hours per year. Both Zone 1 and Zone 2 are considered Division 1 in the US system.
Zone 2 (Div 2) is when an explosive atmosphere is expected to be present only during an upset or during maintenance -- less than 10 hours per year is the number the US Coast Guard arrived at long ago. (see attached). We don't expect a pipe to leak at all. A catastrophe is very infrequent -- decades?
If you routinely take the pipe joints apart for maintenance, or if there are valves in it with leaky packing, you might classify some area around the emitters -- but just a plain pipe running through an area, no. That's unclassified, non-hazardous
Get a copy of ANSI/ISA 12, classification of areas is explained very well in section 12.10. If memory serves, the concept of piping that just runs through an area is covered in there.
Best to you,
Goober Dave
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Typically, a Zone 0 hazard exists when an explosive atmosphere is expected more than 1000 hours per year, and Zone 1 if over 10 hours per year. Both Zone 1 and Zone 2 are considered Division 1 in the US system.
Zone 2 (Div 2) is when an explosive atmosphere is expected to be present only during an upset or during maintenance -- less than 10 hours per year is the number the US Coast Guard arrived at long ago. (see attached). We don't expect a pipe to leak at all. A catastrophe is very infrequent -- decades?
If you routinely take the pipe joints apart for maintenance, or if there are valves in it with leaky packing, you might classify some area around the emitters -- but just a plain pipe running through an area, no. That's unclassified, non-hazardous
Get a copy of ANSI/ISA 12, classification of areas is explained very well in section 12.10. If memory serves, the concept of piping that just runs through an area is covered in there.
Best to you,
Goober Dave
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