Electrical connections within the refrigerator can be an ignition source for flammable vapors. In fact, it’s been reported that there are nearly a dozen sources of ignition in a standard household refrigerator.
The motor under the refrigerator is also a potential ignition source. Explosion-proof refrigerators have their motor and compressor assemblies encased in an enclosure to prevent ignition. In addition, the refrigerator is wired with explosion-proof connections to the receptacle.
If the door has a latch mechanism instead of a magnetic closure, pressure built up in an explosion will blow the door off and cause more serious damage.
Every year, two or three refrigerators explode because of improper storage. Make sure your refrigerators are correct for your application.
Source: Kaufman, James A., Laboratory Safety Guidelines - Expanded Edition, The Laboratory Safety Institute, www.labsafetyinstitute.org.