A hazardous location is any location where an explosion is possible due to the presence of concentrations of flammable gases, vapors, fibers, or dust. An explosion requires the availability of three components: oxygen, fuel, and an ignition source (electrical or thermal energy).
In order for transducers to be used in these environments some specific characteristics are required in order to remove one of these essential components from the equation. The configuration and classification of a sensor for use in hazardous locations is defined by specific criteria established by various agencies.
A Nonincendive mechanism is constructed so that the component is incapable of igniting the specified flammable gas-air or vapor-air mixture. The housing of a nonincendive component is not intended to exclude the flammable atmosphere or contain an explosion.
An Explosion Proof apparatus incorporates the use of an enclosure that is capable of withstanding an explosion of a gas or vapor within it and of preventing ignition of an explosive gas or vapor that may surround it and that operates at such an external temperature that a surrounding explosive gas or vapor will not be thereby ignited. Stellar Technology Models GT23XX is ATEX approved flameproof and the Model GT25XX is CSA approved as explosion proof.
An Intrinsically Safe sensor typically operates at 24 to 36 V and is incapable of releasing sufficient electrical or thermal energy, under normal or fault conditions, to ignite a concentration of fuel. Limitations on current, voltage, capacitance, and inductance ensures that any arcing or thermal effect in the sensor cannot cause an explosion. Stellar Technology’s Model GT2450 is ATEX approved intrinsically safe and Model GT2250 is approved as intrinsically safe by CSA.
A Purged System is a component that has all air removed from the unit thus eliminating the presence of oxygen. This is normally done by replacing the air with nitrogen.
A Simple Apparatus is a switch, thermocouple, resistance thermometer, potentiometer or strain gage which operates below 1.2V, 0.1A, 20 ?J, or 25 mW. However strain gages must be used with a barrier to isolate it from the environment.
Stellar Technology provides sensors for hazardous locations based on the specific conditions of the application. Consult the factory for details.