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Explosion-Proof Refrigerators and
6
Overview
Conventional refrigerators and freezers are not suitable for storing flammable
materials. Such units have components in their electrical and refrigeration
systems that can trigger explosions of flammable air-vapor mixtures inside the
unit and/or in the immediate surrounding area.
The Authority Having Jurisdiction (AHJ) determines if work areas are designated
as a hazardous location with respect to the presence of flammable gases or
vapors. Such locations are defined in (National Fire Protection Association) NFPA
70 Articles 500-501 and OSHA 29 CFR1910.307. Some of these classified areas
are expected to experience concentrations of flammable gases and/or vapors at
or above their lower flammability limits for extended periods of time.
The construction of our explosion-proof units has been evaluated by Underwriters
Laboratories (UL) and are suitable for use in classified areas requiring
Class I, Groups C and D* protected equipment. The electrical components such
as thermostats, wiring, splices, relays and compressor motors on explosion-
proof units are safely housed within explosion-proof enclosures and conduit.
Compressor surface temperatures have been evaluated and determined to
remain below the flash point of materials found in Class I, Groups C and D.
All models have heavy-gauge, rigid, steel construction with a durable enamel
finish. Interiors have epoxy enamel or ABS plastic construction. Each unit is
insulated throughout for energy-efficient operation.
These units are ideal for storing cyclopropane, ethyl ether, ethylene, acetone,
alcohol, benzene, butane, gasoline, hexane, lacquer solvent vapors, naphtha,
natural gas or propane along with many other potentially hazardous materials.
WARNING : For FMS and EXP units where flammable materials are
stored in the cooling chamber, the cooling chamber is considered a
Class I Div1 or Class I Zone 1 hazardous location. Any monitoring
devices placed in the cooling chamber must have an intrinsically
safe rating from an appropriate certification body, such as UL,
CSA, FM etc. (this includes battery or solar powered devices).
Thermocouples for building monitoring systems must be wired
through an electrical barrier designed to provide isolation against
voltage and current spikes, which could cause a spark resulting in
fire or explosion. It is the end user's responsibility to meet these
requirements. Thermo Scientific cannot assist with the selection of
devices, recommend, approve or design any device or monitoring
circuit.
*The notation Class I, Groups C and D is an accepted abbreviation for Class I,
Div 1, Groups C and D; Class I Zone 1 Group IIB.
Freezers
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