Refrigerator Explosion Hazard
Many laboratories, manufacturers, hospitals, and other users of such hazardous liquors as alcohol, ethyl ether, benzene, and volatile petroleum solvents often refrigerate these fluids in an ordinary household refrigerator which may have a number of electrical components within or contiguous to the storage space. These electrical parts, that is, controller, light switch, lamp-holders, etc., within the storage compartment are not designed to be safe for use in atmospheres containing explosive vapors, and fluids which may vaporize to form such an atmosphere or mixtures which may release flammable gases or vapors should not be stored in a refrigerator unless it is specifically designed for the purpose.
Likewise, the condensing unit containing a motor, starting relay, etc., may be so located that upon opening the cabinet door the flammable vapors may be ignited from these sources.
Insurance companies, refrigerator manufacturers, and safety authorities have expressed concern over this practice in view of a number of explosions which have already occurred. Mr. Howard H. Fawcett in a letter to “Chemical & Engineering News,” dated July 18, 1949, describes four serious explosions resulting from the storage of flammable liquids in ordinary household refrigerators.
A Data Card on this subject, Serial No. UI. 439, issued by Underwriters’ Laboratories, Inc., states in part:
“Refrigerating equipment to be safe for such use must be specially designed so as to safeguard all possible sources of ignition inside the refrigerated compartments. Explosion-proof electrical equipment should be employed in connection with all refrigerators in which explosive mixtures may occur. Even if located outside the refrigerated compartment, explosion-proof electrical equipment will be safer as opening the refrigerator containing an explosive mixture may allow some of the mixture to reach electrical sources of ignition. Of course under the circumstances all other outside sources of ignition such as open gas burners should be eliminated.
“Adequate room ventilation around the refrigerator will also assist in minimizing the explosion hazard.”
As yet no refrigerators have been submitted to Underwriters’ Laboratories, Inc. for listing for use in explosive atmospheres, although some water coolers are listed for such use.
Pending the development of refrigerators especially designed for this purpose, it would be desirable in the interest of safety where it is necessary to place flammable liquids in refrigerators:
- to employ a refrigerator with no electrical components within the cooling compartment, and
- to employ a refrigerator the condensing unit of which employs a hermetic or totally enclosed type motor.