What class and division are applied above water on a primary clarifier?

In hazardous location classifications, Class 1 refers to locations where flammable gases or vapors are present. Within Class 1, Division 2 locations are those where explosive concentrations of gases or vapors are not normally present in the air but may accidentally exist.

In the context of a primary clarifier, which is typically found in wastewater treatment processes, there may be a potential for flammable or explosive gases, such as methane, especially in the areas just above the water surface. However, these gases are generally not present in a continuous manner; they may only be present during specific activities or incidents. Therefore, the area above water in a primary clarifier is classified as Class 1 Division 2, reflecting a moderate risk of gas presence that does not meet the criteria for continuous exposure.

This classification is crucial for selecting appropriate equipment and ensuring safety measures are implemented. Equipment installed in a Class 1 Division 1 location would need to be designed for environments with continuous exposure to flammable gases, which would be unnecessarily stringent and more costly for the expected conditions in a primary clarifier.