Class 1, Division 2 Explosion Proof Air Conditioners
Class 1, Division 2 is the most common hazardous location classification we work with. The majority of US oil refineries, gas processing plants, and petrochemical facilities are classified Class 1, Division 2, Groups C and D for their primary work areas and adjacent spaces.
If someone at your facility mentions “explosion-proof AC” without specifying a classification, there’s a good chance this is what they need.
What Is a Class 1, Division 2 Location?
Under the National Electrical Code (NEC Article 500), Class 1 locations are those where flammable gases or vapors may be present in ignitable concentrations. Division 2 means the hazardous condition exists only under abnormal conditions — not as a routine part of normal operations.
Specifically, Division 2 covers:
- Locations where volatile flammable liquids or gases are handled, processed, or used, but where the liquids, gases, or vapors are normally confined within closed containers or systems — and can escape only through accidental rupture or breakdown
- Locations where ignitable concentrations are normally prevented by positive mechanical ventilation, but could become hazardous through failure of that ventilation
- Locations adjacent to Division 1 areas where ignitable concentrations might occasionally be communicated (unless prevented by adequate positive-pressure ventilation with effective safeguards)
Common Class 1, Division 2 Environments
- Oil refineries — process unit perimeters, pump areas, compressor buildings
- Natural gas processing plants — around compressors, dehydration units, storage areas
- Petroleum product storage facilities
- Pipeline pumping stations
- Chemical plants with enclosed processing areas
- Commercial paint spray areas where flammable solvents are used but ventilation is maintained
- Gas meter and regulating equipment in utility stations
- Aircraft fueling areas
The key distinction from Division 1: In a Division 2 area, you should not normally be able to smell or detect flammable gases — they’re present only under fault conditions. In Division 1, normal operations involve routine exposure to the hazard.
Class 1 Groups: A, B, C, and D
The group specifies the particular flammable material in your environment. This determines which explosion-proof motors and components are required.
Group A — Acetylene
Group A covers acetylene, which has the lowest minimum ignition energy of any common industrial gas — approximately 0.017 mJ, compared to 0.25 mJ for hydrogen and 0.24 mJ for methane. It also forms explosive compounds with copper, silver, and mercury on contact.
We do not offer explosion-proof air conditioning for Group A environments. The equipment requirements are so stringent that practical HVAC solutions are essentially unavailable. If your facility handles acetylene, consult your safety engineer about isolation, ventilation, and administrative controls as primary risk mitigation strategies.
Group B — Hydrogen and High-Hazard Gases
Group B materials have very low ignition energy. Group B-rated equipment meets both Group B and downstream group requirements.
Common substances: Hydrogen, butadiene, ethylene oxide, propylene oxide, acrolein
Common Division 2 applications: Hydrogen generation facilities, certain chemical plants, semiconductor fabs with hydrogen supply systems
Group C — Ethylene and Ether Vapors
Group C represents an intermediate hazard level. Equipment rated for Group C also satisfies Group D.
Common substances: Ethyl ether, ethylene, cyclopropane, ethylene dichloride, trimethylamine
Common Division 2 applications: Chemical processing facilities, pharmaceutical plants, laboratories with enclosed ether or ethylene storage
Group D — Petroleum Vapors and Natural Gas
Group D is by far the most common classification we work with. If you’re in oil and gas, refining, or petrochemical processing, your classified areas are almost certainly Group D — or Group C and D combined on the nameplate.
Common substances: Gasoline, hexane, naphtha, benzene, butane, propane, natural gas, alcohol, acetone, ammonia, lacquer solvent vapors
Common Division 2 applications: Virtually all outdoor and semi-enclosed areas at oil refineries, gas plants, pipeline stations, LPG facilities, and petroleum storage
Division 2 vs. Division 1: Why It Matters for Equipment and Cost
Division 2 allows some components that are not permitted in Division 1. Specifically:
- Non-incendive circuits can be used in some control applications in Division 2 (not allowed in Division 1)
- Purge and pressurization systems can qualify equipment for Division 2 in some configurations (used more rarely for air conditioning)
- General-purpose enclosures may be acceptable for some components that make or break current — if the current interruption is done in a hermetically sealed chamber (like a compressor)
In practice, for air conditioning equipment, the differences are primarily in motor specification and the scope of conduit/sealing work. Division 2 modifications are typically less extensive — and less expensive — than Division 1.
If you’re on the fence between Division 1 and Division 2, that determination should come from your facility’s area classification drawings (HAC drawings) or your safety/process engineering team — not from a cost preference. Call us if you need help interpreting the documents.
Class 1, Division 2 Air Conditioner Modifications
We modify standard air conditioning units — most commonly Bard wall-mount units — for Class 1, Division 2 service:
- Motor replacement: All motors replaced with Division 2-appropriate explosion-proof motors for the applicable group (most commonly Groups C & D)
- Conduit and sealing: Re-wiring with rigid metallic conduit; all conduit entries sealed per NEC 501.15
- Enclosure upgrades: Control and junction boxes upgraded to explosion-proof equivalents where required
- Optional coil coating: Recommended for corrosive, coastal, or chemically aggressive environments
- Documentation: Full compliance documentation included
Pricing
Class 1, Division 2, Group C&D — inside unit (evaporator) only: Starting at $6,700, up to $7,600 for 3-ton units
Class 1, Division 2, Group C&D — full inside + outside explosion-proofing: Starting at $9,000 for 8,000 BTU, approximately $10,000 for 3-ton units
Larger units and special requirements are quoted individually. Call us — quotes typically come back within 24–48 hours.
Frequently Asked Questions
Do I need a Class 1, Division 2 unit or can I use a standard commercial AC? If your area is classified Division 2, you need explosion-proof equipment. Standard commercial units are not rated for hazardous locations and should not be used in classified areas — doing so creates a life safety risk and typically violates OSHA and local fire code requirements.
My condenser is outside the classified area. Do I need to explosion-proof it? If the condenser is located in a non-classified area, you may only need the indoor evaporator section explosion-proofed. This is a common configuration for control rooms in refineries — the wall serves as the classified boundary. We can help you work through the specifics.
Can I use a Division 2 unit in a Division 1 area? No. Division 2 equipment is not rated for Division 1 use. Division 1 locations require Division 1-rated equipment throughout.
Related Pages
- What Is an Explosion Proof Air Conditioner? — complete guide with classifications, pricing, and real installations
- Class 1, Division 1 — for areas where flammable gases are present under normal operating conditions
- Class 2, Division 1 — for combustible dust environments
- Class 2, Division 2 — for combustible dust accumulation environments
- NEC Article 500 vs. 505 — Class/Division vs. Zone classification
- Explosion Proof Mini Splits — the most affordable option available today
- Explosion Proof Bard Air Conditioners — our most common Class 1, Div 2 product
- How Much Does It Cost? — full pricing breakdown
- How to Choose — step-by-step buyer’s guide
- FAQ