What class must a type 3 operating storage tank level indicator servo compartment be approved for?

A type 3 operating storage tank level indicator servo compartment must be approved for Division 1, Group D. This requirement is linked to the potential hazards in locations where flammable gases or vapors may be present. In the case of Group D, it pertains specifically to locations that may have flammable gases such as propane or butane.

Thus, the selection of Division 1, Group D for the level indicator servo compartment ensures that the equipment is capable of operating safely in environments where ignitable concentrations of vapors can occur continuously or frequently due to the storage material's nature. This classification is important for preventing potential ignition sources in flammable atmospheres, thus ensuring overall safety and compliance with hazardous location standards.

The other classifications listed (Division 1, Group C and Division 2, groups C and D) do not align with the requirements for a type 3 operating storage tank level indicator servo compartment, as they either refer to different types of hazardous materials or different operational scenarios.