Recently HSEO received an enquiry about using under-bench domestic refrigerators for storage of chemical samples. We revisited the issue and came to the following conclusion: refrigerators shall not be used to store containers/reagent bottles/sample vials which will release flammable vapor, unless they are spark-free and meet the following safety specifications:

1. Must not be of the frost-free or auto-defrost type.
2. Must have the internal light source removed or replaced with a spark-free type.
3. Must have the thermostat and compressor positioned outside, instead of inside, the storage space of the refrigerator.

Improper use of domestic refrigerator for storage of containers/reagent bottles/sample vials emitting flammable vapor may pose a significant risk of explosion. The following is an example of such an explosion of a domestic refrigerator at the University of Vermont in year 2000 (http://esf.uvm.edu/uvmsafety/labsafety/chemsafety/colpix/colpictures.html).

Even though there may be domestic refrigerators, with no interior electric parts, appear to fulfill the above specifications, the supplier must provide certificates to prove they are spark–free, otherwise the user will have to bear full liability when there is a mishap involving storage of flammable and volatile substances in such refrigerators.

On the other hand, domestic refrigerators can be used to store non-flammable and non-volatile substances. Chemical samples that are non-flammable and non-volatile may be stored in such refrigerators, with the following conditions:

1. All containers are capped or sealed and placed in secondary containers.
2. All containers in the refrigerators are labeled with contents, owner and date of acquisition or preparation.
3. Such refrigerators are labeled with a prominent sign “FOR STORAGE OF NON-FLAMMABLE AND NON-VOLATILE SUBSTANCE ONLY”, indicating that they are not for storage of flammable and volatile substances.

Please feel free to contact Health, Safety and Environment Office if you have further questions regarding this or other laboratory safety issues.