Kooltronic Blog

In hazardous locations like refineries and chemical processing plants, "standard" equipment isn't just insufficient; it's a liability. Having explosive gases onsite means that every piece of electrical equipment must be safeguarded as a potential ignition source. To avoid accidents, the electrical equipment located within these environments must adhere to the strict safety guidelines specified in the National Electric Code (NEC). Published by the National Fire Protection Association (NFPA), the NEC standards are referenced primarily in the United States. These standards limit the types of materials and circuitry that can be used in hazardous areas and promote the safe installation of electrical wiring and equipment.

Outside the U.S., regulatory agencies such as the International Electrotechnical Commission (IEC), and directives (ATEX) provide an alternative system to categorize and safeguard equipment use in hazardous areas. It is important to note that NEC, IEC, and ATEX guidelines extend to enclosure cooling products, which require protection (including air movers, compressors, controls, and relays) to ensure safe operation.

This article focuses on NEC standards and highlights the different aspects of cooling enclosures in Class I, Div. 1 and 2 hazardous locations.

Explaining NEC Class, Division, and Group (NFPA 496):

Class:

The "Class" indicates the type of ignitable substance present in a hazardous area.

1. Class I covers the presence of gases, vapors, or liquids. This designation also implies that the amount of gas/vapor present in the atmosphere is sufficient to produce a flammable or explosive mixture (e.g., refineries, petrochemical plants).
2. Class II includes combustible dust (e.g., coal plants, grain silos).
3. Class III covers ignitable fibers or combustible particles (e.g., textile/paper mills, cotton gins).
   
   

Division:

Division refers to the likelihood or frequency that an ignitable gas/vapor is present during various business operation cycles. This is a separate classification from Zone, which is used in the IEC guidelines and ATEX directives.

1. Division 1 (normal) indicates that the ignitable substance is present during typical or routine business operations, which implies a greater risk of fire or explosion (and additional protection requirement).
2. Division 2 (abnormal) designations indicate that an ignitable gas is present at that location, albeit contained, and unlikely to be released in large enough quantities to produce an explosion during typical business operation.
   
   

Group:

In Class I, Div. 1 and 2 locations, the Group letter signifies the type of hazardous material present. The various materials included in the group set are categorized by a set of ignition characteristics, including flash point, ignition temperature, explosion pressure, and surface temperatures.

1. Group A: Acetylene
2. Group B: Hydrogen, butadiene, ethylene oxide, propylene oxide, and acrolein
3. Group C: Ethylene, cyclopropane, and ethyl ether
4. Group D: Acetone, ammonia, benzene, butane, ethanol, gasoline, hexane, methane, methanol, naphtha, natural gas, propane, and toluene
   
   

Understanding Class I, Div. 1 & 2 Areas

⚠️Class I, Division 1 (C1D1):

• Assessment: Ignitable gases/vapors are normally present during business operations.
• Risk Level: High – persistent or frequent risk.
• Protection Required: Explosion-proof equipment, intrinsically safe systems, purge or pressurization system on enclosure.
  
  

⚠️Class I, Division 2 (C1D2):

• Assessment: Ignitable gases/vapors are handled at the location, but only present during an accident or system failure.
• Risk Level: Moderate – occasional or abnormal risk.
• Protection Required: Non-sparking equipment, enclosed-break devices (hermetically sealed), or standard C1D1 equipment.
  
  

Click image to enlarge.

The Enclosure Cooling Solution

Cooling heat-sensitive equipment in hazardous locations requires more than just a fan; it requires a highly engineered, NEC-compliant solution. UL Recognized per NFPA 496, Kooltronic's HL Series Air Conditioners (360° view below) are engineered for closed-loop cooling of electrical enclosures and control cabinets in NEC Class I, Divisions 1 and 2 (Groups A, B, C, and D) hazardous locations. HL units feature a patented, award-winning design, A1L nonflammable refrigerant, and up to 24,000 BTU/H of cooling capacity in single or 3-phase power. With all electrical components sealed in a pressurized compartment, the HL Series Air Conditioners utilize an enclosure's existing purge system to maintain 24/7 reliability in safety-critical environments.

Key Benefits:

• Risk Mitigation: Reduce the risk of fire or explosion in NEC Class I Div. 1 & 2 hazardous locations.
• Reduced Costs: Avoid costly repair or replacement costs for components damaged from excessive heat.
• System Uptime: Ensure production and reduce the risk of revenue loss during downtime.
• Regulatory Compliance: Ensure your offshore or inland operations meet the standards of NEC Class I, Div. 1 & 2 (Groups A, B, C, D), as well as IEC Class I, Zone 1, Groups IIA, IIB plus hydrogen, and IIC Hazardous Locations when used with an approved Type X/Z Purge System.

Ultimately, decoding the requirements of the National Electric Code Class I, Div. 1 & 2 standards is about recognizing that "standard" equipment simply isn't engineered for these high-stakes scenarios. Avoiding costly downtime is, of course, a critical operational goal, but it pales in comparison to the primary mission: preventing a catastrophic fire or explosion. By investing in highly specialized, highly engineered enclosure cooling equipment that meets NEC standards, you are not just maintaining compliance, you are prioritizing the safety of your team and ensuring the long-term integrity of your operations.

Contact an application specialist for information on the Kooltronic HL Series Air Conditioners or other thermal management products for harsh environments.