Is this a frequent operation? Is this operation indoors or outdoors? If indoors, what is the ventilation method and rate? Is the ?1-gallon container? of ethanol the only container involved with flammable materials? What other quantities are stored nearby? I could probably think of a few more questions and still not be able to answer definitively.
The general Standard is NFPA 30.
Like getting a qualified electrician to install the job, you need a qualified person who knows and understands the full process to classify it. It would probably be minimal, possibly none at all, but without a solid understanding of the entire operating process, it is impossible to answer definitively.