What class and division above water on a primary clarifier?

What class and division above water on a primary clarifier?

• A. Class 1 Division 2
• B. Class 1 Division 1
• C. Class 2 Division 2
• D. Class 3 Division 1

Answer: (A)

In hazardous location terms, gases and vapors are protected under Class I. Division 1 means the flammable atmosphere is present during normal operation, while Division 2 means the hazard is only present under abnormal conditions. Above the water on a primary clarifier, flammable gases such as methane or hydrogen sulfide can be released from the wastewater, but they aren’t expected to be present all the time during normal operation. So this location is designated as Class I Division 2, reflecting a hazard that may occur under abnormal conditions rather than continuously. This is why equipment there is chosen to be rated for Class I Division 2 environments. The other classifications don’t fit: Class II would cover dust, which isn’t the primary concern above water in a clarifier, and Class III covers fibers, which isn’t applicable here.

In hazardous location terms, gases and vapors are protected under Class I. Division 1 means the flammable atmosphere is present during normal operation, while Division 2 means the hazard is only present under abnormal conditions. Above the water on a primary clarifier, flammable gases such as methane or hydrogen sulfide can be released from the wastewater, but they aren’t expected to be present all the time during normal operation. So this location is designated as Class I Division 2, reflecting a hazard that may occur under abnormal conditions rather than continuously. This is why equipment there is chosen to be rated for Class I Division 2 environments. The other classifications don’t fit: Class II would cover dust, which isn’t the primary concern above water in a clarifier, and Class III covers fibers, which isn’t applicable here.