fragment or sentence

It is a sentence fagment. sentence is a group of words containing a subject and predicate. A sentence fragment fails to be a sentence in the sense that it cannot stand by itself, it does not contain even one independent clause.

Thanks, Contrex, for the fast reply.

The device moves like flame; hence, the name.

If I use a semi-colon after 'flame', does it solve the problem? If not, please rephrase it for me.

I would like to repeat that I appreciate your guidance very much.

Best wishes

Comma after "flame", definitely nothing after "hence".

The device moves like flame, hence the name.

Many thanks, Contrex.