Do I Need Explosion Proof Protection from Groups C and D?

Explosion proof protection is crucial for maintaining safe operations in hazardous locations. Most individuals understand the classification of their operating facility; but going beyond this, it is important to know which groups are applicable to one’s business. Using luminaries with incorrect groupings can be both extremely dangerous and expensive. This practice is comparable to buying car insurance when you own a bicycle – you’ll end up paying more for something that isn’t entirely useful or applicable to your needs.

With this in mind, groupings for explosion proof luminaries offer protection for specific flammable materials. For example, Group A is for environments where acetylene, a colorless gas that is used for welding, heat treatments and chemical synthesis, may be present in the Class I hazardous location. While Group B pertains to hydrogen, butadiene, ethylene oxide and propylene oxide. Hydrogen, being the most common flammable substance from the group, is used to produce ammonia and during oil refining. At concentrated levels, hydrogen is extremely explosive.

Protection from volatile Class I, Groups A and B substances is only required if such materials are present in the applicable environment. It is possible to need Class I, Divisions 1 & 2 protection, but not necessarily protection from substances under Group A or B, or both. To shine more light on this topic, this article dives deeper into the classified groups by expounding on Class I, Groups C and D.

Group C (Ethylene) 

Ethylene, at concentrations of 27,000 parts per million, is a reactive colorless gas, which can turn into a liquid at low temperatures. Over exposure to this substance may cause dizziness and fainting. As a leading petrochemical, numerous manufacturers rely on the material to produce polymers such as polyethylene (PE), polyethylene terephthalate (PET), polyvinyl chloride (PVC) and polystyrene (PS). Interestingly, ethylene is used by farmers to stimulate the ripening process of fruits and flowers. Regulating concentrations in the environment is done using active ventilation and constant monitoring.

Due to the specific applications of the substance, businesses that do not work with or around petrochemicals, and do not engage in commercial fruit ripening, will most likely not need protection from Class I, Group C. However, it is important to consider that other volatile materials under this category includes Cyclopropane (C3H6) and Ethyl Ether (used in fuel additives and the production of solvents). If you’re unsure if these substances exist in the industrial facility, it might be worth performing atmospheric testing for verification.

Group D (Propane)

Propane is a hydrocarbon (flammable) gas with several mainstream applications. It is a very common material that can be found in both residential homes (for cooking or heating) and industrial facilities (for powering generators, manufacturing ceramics, die casting and asphalt melting). The main issue with propane is its pressurized state during storage, which can make explosions very intense. Signs that a business is using propane includes the presence of large propane storage tanks, compact propane cylinders and propane refill stations in or around the facility. Although common, propane is regulated closely by safety regulators – it holds a daunting F+ rating under EU Directive 67/548/EEC. Under Group D, Ammonia, Acetone, Bezene, Butane, Ethanol, Gasoline, Methanol and Natural Gas are also included in this Class I category.

As mentioned earlier, one of the most effective ways to check if you need explosion proof protection from certain groups is atmospheric testing. Conducting such tests before setting up your lighting system in the hazardous location can help you decrease costs (since luminaries with higher levels of explosion proof protection tend to cost more) and streamline compliance with industrial safety standards.

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