Abstract: AT APPROXIMATLY 8:50 AM ON THE MORNING OF FEBRUARY 27, 1986, AN EMPLOYEE OF A PLUMBING COMPANY INVOLVED IN A CONSTRUCTION OPERATION WAS PURGING NATURAL GAS LINES LEADING TO ABOVE GROUND GAS-FIRED SPACE HEATERS. THE EMPLOYEE WAS BELIEVED TO HAVE PURGED FOUR OTHER HEATERS IN THE BUILDING PRIOR TO THE ONE IN THE COACHS' LOCKER ROOM. THE EMPLOYEE ATTEMPTED TO PURGE AND FIRE UP THE HEATER, USING THE THERMOSTAT. IT WOULD NOT START. HE THEN ATTEMPTED TO LIGHT THE HEATER WITH A MATCH. THAT METHOD ALSO FAILED. HE THEN UNCOUPLED THE GAS UNION AT THE SPACE HEATER AND PURGED THE SYSTEM FOR FIVE MINUTES. HE RECONNECTED THE UNION AND SET THE THERMOSTAT TO 80 DEGREES. THE SYSTEM FUNCTIONED AS DESIGNED. THE HEATER AND THE GAS-CONTAMINATED ATMOSPHERE IN THE ROOM BOTH IGNITED. AN EXPLOSION RESULTED, CAUSING EXTENSIVE DAMAGE TO THE BUILDING AND SERIOUS INJURY TO FOUR OF THE NINE PEOPLE INJURED.