The Bureau of Mines conducted a study to develop a standard fire test for 5-gal containers used for storing combustible fluids in underground coal mines. A standard test method was developed that evaluates the performance of the container in a 4-min tray fire. Bureau investigators used the standard test method to evaluate several types of closed 5-gal plastic and metal cans in outdoor tests. Each can tested contained 1 gal of non-fire-resistant (nfr) hydraulic oil. A container failed the test if it lost its contents in any of seven trials. Contents spilled either as a result of thermal rupture or melting. Fewer than 10 pct of the metal containers failed this criterion, but all the plastic containers failed. The metal container failures were usually due to tipping over during pressure relief, which spilled the nfr oil. Replacing the nfr oil in the container with kerosene resulted in failure of more than 30 pct of the metal containers. The standard tests and preliminary tests showed that plastic containers are not equivalent to metal containers in their ability to contain combustibles such as lubricants and greases in a fire. For solvents and lubricants more volatile than nfr hydraulic oil, approved metal safety containers are recommended.