For Class 2 locations, the temperature mark must be less than what?

In Class 2 locations, which involve dust hazards, the temperature mark must be less than the ignition temperature of the dust present. Understanding the ignition temperature is crucial because it is the minimum temperature at which a dust cloud will ignite when exposed to an ignition source. If the temperature mark exceeds the ignition temperature, there is a significant risk of explosion or fire when the dust accumulates and is suspended in the air.

The other options do not accurately reflect this safety requirement. The flash point relates to the temperature at which a substance can vaporize to form an ignitable mixture in air under certain conditions, but it is more relevant for Class 1 locations dealing with flammable gases and vapors. Boiling point and melting point are also not pertinent in the context of assessing safety in Class 2 locations as they don't address the ignition potential of dust specifically. Thus, maintaining a temperature mark below the ignition temperature is essential for ensuring safety in environments where combustible dust may be present.