What damage can occur to an immersion element if it is not immersed in water?

When an immersion element is not submerged in water, it can experience overheating due to high watt density. This occurs because the element generates heat, but without water to absorb and dissipate that heat, the temperature of the element continues to rise. As a result, excessive temperatures can lead to the melting of the element, damaging it beyond repair. This is a crucial aspect of proper equipment maintenance and operation; immersion elements rely on being in contact with water to function correctly and safely.

The other options do not accurately describe what happens to an immersion element when it is not properly immersed. For instance, it does not function more efficiently without water; in fact, the opposite is true. While it could potentially develop rust over time, that is not an immediate consequence of being unimmersed, as rusting typically requires moisture over an extended period. Lastly, while cracking can happen to various materials under certain conditions, it is the extreme heating issue directly leading to melting that is the more immediate and severe concern for an immersion element.