Using a hotplate with flammable liquid Table 10-3 Department: Chemistry Description of Operation: Use of stirring hotplate with flammable liquid By: Review Team Date: What if? Answer Probability Consequences Recommendations Use on unventilated benchtop Flammable vapors could accumulate and reach source of ignition fire High Extensive damage/downtime and costs Use in fume hood Overexposure to toxic vapors High Adverse health effects Use in fume hood Mechanical failure of fume hood exhaust fan Lack of exhaust but vapors still accumulate and ignition sources still present Moderate Adverse health effects Interlock hotplate power to exhaust monitor Fire Moderate Damage Use explosion proof hotplate Power failure during use (see also loss of heat and loss of stirring below) Lack of exhaust, vapors may accumulate but at lesser magnitude, potential fire Very high Damage/health effects Connect exhaust fan to emergency power Reaction becomes unstable Very high Failed experiment, exposure to unknown products Conduct a review of all possible reactions and outcomes Hotplate malfunction, electrical arcing (switch/ thermostat) Possible fire in hotplate and ignition of solvent vapors Moderate Equipment damage/personnel injuries Check electrical connections (plugs and wires); pretest hotplate before starting; use explosion proof hotplate Hotplate malfunction, supplies too much heat Heat material above flash point Moderate Fire, damage, personnel injuries Interlock hotplate to temperature feedback loop Reaction becomes unstable Moderate Personnel injuries Do not leave reaction unattended; check temperature of reaction at regular intervals Unintended reaction occurs Moderate Hazardous byproducts Conduct a review of all possible reactions and outcomes Hotplate malfunction; supplies too little heat; if no heat, see loss of power above Reaction unsuccessful Moderate Lost time and materials Interlock hotplate to temperature feedback loop Reactants degrade/ evaporate Moderate Lost time and materials; hazardous byproducts Do not leave reaction unattended; check temperature of reaction at regular intervals Loss of Stirring Superheating of portion of flask contents Very high Vessel fails/fire Interlock hotplate to temperature feedback loop Unintended reaction occurs High Hazardous byproducts Conduct a review of all possible reactions and outcomes Reaction unsuccessful High Lost time and materials Do not leave reaction unattended; check temperature and stirring of reaction at regular intervals
Spill from container being heated Flash fire High Fire/damage/ personnel injuries Do not handle hot vessel Reaction unsuccessful High Lost time and materials Do not leave reaction unattended Heating period is too long Open container boils dry High Failed reaction Connect hotplate to timer and temperature feedback loop Vessel breaks High Vessel fails/fire See above Reaction unsuccessful High Lost time and materials Do not leave reaction unattended Heat period is too short Unreacted starting material High Hazardous byproducts Connect hotplate to timer and temperature feedback loop Unstable products High Personnel injuries Conduct a review of all possible reactions and outcomes Reaction unsuccessful High Lost time and materials Do not leave reaction unattended Container breaks Flash fire High Fire/damage/ personnel injuries Check container for signs of prior damage or use new container Residual process gas in equipment when opened Vessel breaks High Fire/Damage/ personnel injuries Do not use a closed container; use container with a pressure relief device Vessel cannot be opened High Lost time and materials See above Unintended reaction occurs High Hazardous byproducts Conduct a review of all possible reactions and outcomes This file is excerpted from “Identifying and Evaluating Hazards in Research Laboratories: Guidelines developed by the Hazard Identification and Evaluation Task Force of the American Chemical Society’s Committee on Chemical Safety”. © Copyright 2015 American Chemical Society