Abstract: Employees #1 and #2 were in the wash bay of a trucking facility draining water from the bottom of a 1,400-gallon truck tank of butane BG mix into the floor drain. Employee #3 had stopped to talk with them. The water and butane mixture traveled via a drain pit from the back of the truck to the front of the truck. The vapors from the butane accumulated and reached the pilot light of a Hotsy, approximately 3.5 feet above the floor in a closet at the front of the wash bay. The pilot light ignited the butane vapors into a fireball. Flames engulfed the entire wash bay and shot 30 feet out the back door. Employees #1 and #2 sustained serious burns on their backs, arms, legs, and hands. Employee #3 suffered from burns primarily on his hands. All three workers were hospitalized for treatment of their injuries. Further investigation revealed that Employees #1 and #2 had misjudged the amount of butane mix coming off with the water.