chill, fat chance that his flask will explode. 2 factors, combination of hard vacuum and thin wall do that, one factor seldom produce implosion... By the way, one should allways wear protection while working in bthe lab, for eyez, hands and a lab-coat. If the flask is in the fume hood it can't relly cause no harm even if it blows. Fuck, there are more damgerous things in the lab to worry about.
"Turn on, Tune in and Drop Out"