Editor's note: This is the first of three blog posts looking at hazardous location certifications for sensors. You can find the second, on Intrinsically Safe protection, here, and the third, on Explosion Proof protection, here.
Industrial areas that present a risk of fire or explosion are called hazardous locations. Sensors that will be installed in these areas can potentially ignite flammable vapors, dust, or fibers. To prevent a disaster, these sensors must be designed in a way that eliminates risk.
In this post, we will cover the basics of hazardous locations, namely protection methods and hazard types as defined by CSA International, a globally recognized testing and certification organization.
There are several methods of protection against fire and explosion. The two that we most often use at APG are intrinsic safety wiring and explosion proof housings. As their names suggest, one is a wiring and power management technique, with the other is a containment technique with a durable housing.
Intrinsically safe wiring is a power management technique. By limiting the amount of electricity in a device, to the point that it cannot produce an ignition, we create a device that is intrinsically safe. Without the potential of ignition, safety becomes intrinsic to the design of the device.
Also known as flame proof, this method simply uses a housing that will withstand and contain an internal spark, ignition, or explosion. In other words, if a sensor’s electronics do ignite vapors or dust inside the sensor housing, it will never break through the actual sensor housing, thereby eliminating any chance of an explosion or fire.
Not all hazardous locations are created equal. CSA has broken these areas down into classes, and divisions for North America, and classes and zones for Europe. While the terms vary slightly in specificity, they are consistent in purpose.
For both continents, classes defined the type of hazard. The three categories are class 1 for vapors, class 2 for dust, and class 3 for fibers. Divisions, for North America, and Zones, for Europe, identify the extremity of the hazard. There are only two divisions:
Hazard is likely (division 1)
Hazard exists under abnormal conditions (division 2)
Conversely, there are three zones:
Hazard is constant (zone 0)
Hazard exists during normal operation (zone 1)
Hazard does not normally exist (zone 2)
Using good protection methods, and keeping sensors in their appropriate areas can keep hazardous locations safe. Our sensors undergo rigorous testing to ensure they are safe and properly marked.
We’ll get a bit more detailed about hazardous locations in the weeks to come.Our Measurement Experts welcome questions about hazardous locations and protection methods. If you’d like to know specifically about our products, give us a call at 888-525-7300 or send us an email.