What does that certification label mean? – Extreme Telematics Corp. (ETC)

Every product that is certified for use in a hazardous location has a label on the side.  Most operators really only look at what area it is certified to be installed in and ignore the rest of the information.  These other parameters can often be very important when deciding which controller or sensor to purchase and where it can be used.  Some of the items are self-explanatory, but it is important to know some of the less common information.

Classes:

The class is used to identify the type of hazard. Class I is most commonly found in the oil and gas industry, where Class II is typical of farming operations, and Class III is in manufacturing.

• Class I – Flammable gases or vapors
• Class II – Combustible or conductive dust
• Class III – Ignitable fibers in the air

Zone/Divisions:

The zone (previously called divisions) is used to quantify the intensity of the hazard.  The lower the number, the more extreme the hazard.

• Zone 0 (Division 1) – The explosive atmosphere is continuous
• Zone 1 (Division 1) – The explosive atmosphere is likely
• Zone 2 (Division 2) – The explosive atmosphere is not normal

 

Ex Code:

The Ex code specifies the type of protection method that is employed to prevent an explosion and the area it is safe to be installed in.  Intrinsically safe means that by its nature, the device does not have the capability to create an explosion because there is not the ability to arc or heat up enough to ignite gas.  Conversely, a flameproof or explosion proof device may cause an explosion under failure, but it will be contained within the device.

• Ex ia – Intrinsically Safe for Zones 0, 1, 2

• Ex d – Flameproof (Explosion Proof)

Gas group:

The gas group identifies the type of gases that can be present in the hazardous area.  If a product is rated for a given gas group, it is safe to be in an area with that gas or the groups of gases that are less severe.  IIC is the most severe and IIA is the least severe.

• IIA (D) – Propane, Methane
• IIB (C) – Ethylene, Hydrogen Sulfide
• IIC (A + B) – Hydrogen, Acetylene

Surface temperature code:

The surface temperature code specifies the maximum surface temperature of the device and helps to set the allowable ambient temperature.  The lower the surface temperature, the less likely it is to ignite gas and the higher the allowable ambient temperature.  There are many different temperature codes and steps in between (A to D), but here are the most common:

• T2 – 300 C/572 F
• T3 – 200 C/392 F
• T4 – 135 C/275 F

As you can see, it is important to be able to understand the certification label.  Not only will it tell you the area that the device can be installed in, it also tells you the types of gasses, allowable ambient temperature, and how the device is designed to be protected from the hazard.

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