How to Choose an Explosion Proof Air Conditioner

Buying an explosion-proof air conditioner is not like buying a standard commercial unit. There is no catalog to browse, no star ratings to compare, and no off-the-shelf option that works for every situation. Every unit is modified or fabricated to a specific set of requirements — and getting those requirements right before you start shopping is the difference between a smooth project and an expensive mistake.

This guide walks through the key decisions, in order. By the end, you will have the information you need to call us and get a quote within 24–48 hours.

If you want the full technical background first, read our complete guide to explosion-proof air conditioning.

Step 1: Determine Your Hazardous Location Classification

This is the most important step — and it is one that has to come from your facility’s documentation, not from a guess.

Start with your HAC drawing. Hazardous Area Classification (HAC) drawings are part of your facility’s electrical design documentation. They show which areas are classified, what classification applies, and the Class/Division/Group for each zone. Your EHS team, facility engineer, or the original electrical design package will have these.

If you do not have HAC drawings, you will need a qualified electrical engineer to classify your area under NEC Article 500 (or Article 505 if your facility uses the Zone method). This is not something to estimate or guess at. An incorrect classification means the wrong equipment specification, which is both a code violation and a safety hazard.

What you are looking for:

Class — Is the hazard a flammable gas or vapor (Class 1), combustible dust (Class 2), or ignitable fiber (Class 3)?

Division — Is the hazard present under normal conditions (Division 1) or only under abnormal conditions (Division 2)?

Group — What specific material is the hazard? Groups A/B/C/D for Class 1, Groups E/F/G for Class 2.

The most common answer: If you are at an oil refinery, petrochemical plant, or natural gas facility, your classification is very likely Class 1, Division 2, Groups C and D. This covers the vast majority of our work.

Step 2: Size Your Cooling Load

How much cooling does the space need? The right answer comes from a heat load calculation — not a guess.

Factors that drive cooling load:

Space dimensions — square footage and ceiling height. A 10x12 instrument shelter has a very different load than a 40x60 equipment building.

Heat-generating equipment — servers, VFDs, motor control centers, analyzers, electrical panels, transformers. This is often the dominant factor. A control room with minimal electronics might need 1 ton. The same room packed with VFDs might need 5 tons.

Solar exposure — direct sun on the structure adds significant load, especially in southern and desert climates. A metal shelter in full Texas sun can add 30–50% to the cooling load compared to the same shelter in shade.

Ambient temperature — desert sites, Gulf Coast humidity, and northern cold all affect sizing differently. Units are typically rated at standard conditions (95°F ambient).

Target indoor temperature — most industrial applications target 85–95°F to protect electronics, not the 72°F of an office. A higher setpoint reduces the required cooling load.

Common size ranges:

  • Small instrument shelters: 0.5–1 ton (6,000–12,000 BTU)
  • Typical control rooms: 2–3 tons (24,000–36,000 BTU)
  • Larger equipment buildings: 3–5 tons (36,000–60,000 BTU)
  • Large modular buildings or pressurized shelters: 10–20+ tons

Not sure of your load? Give us the space dimensions and a list of heat-generating equipment inside. We can help you estimate.

Step 3: Decide — Inside Only, or Inside and Outside?

This is the question that most directly affects your cost. Getting it right can save you 30–40%.

Inside only (evaporator section only): The wall or ceiling separating your classified space from the exterior serves as the classification boundary. The condenser (outdoor section) sits outside the classified area in non-classified atmosphere. Only the indoor evaporator requires explosion-proof modification. This is the most common and most affordable configuration.

When it applies: Control rooms with one wall on a classified area exterior. Equipment shelters where the condenser can mount outside the classified zone. Any installation where you can locate the outdoor section in clean air.

Full inside + outside (both sections): Both the indoor and outdoor sections of the air conditioner are within the classified area. Both require explosion-proof modification. This is required when the condenser cannot be located outside the classified boundary.

When it applies: Equipment shelters or blast-resistant modules entirely within a process area. Installations where running refrigerant lines or condenser air outside the classified area is impractical. Skid-mounted units where the entire skid is in a classified zone.

Starting price comparison (Class 1, Div 2, Group C&D):

  • Inside only: from $6,700
  • Full inside + outside: from $9,000

See our full pricing guide for a complete breakdown.

Step 4: Choose a Unit Configuration

Different unit types suit different installation conditions. Your cooling load and physical constraints determine which one fits:

Wall-mount (Bard) — The most common choice for control rooms and equipment buildings. Installs through an exterior wall. Self-contained, compact footprint. Available from fractional tonnage to 5 tons. Our most frequently modified unit. Choose this for: most applications under 5 tons where you can cut a wall opening.

Mini split — The most affordable configuration available today. A compact indoor head mounts on a wall or ceiling, with the condenser outside. Choose this for: budget-constrained applications up to ~3 tons where you have indoor wall or ceiling space for the evaporator head.

Window / through-wall (small) — Currently unavailable due to new refrigerant standards. Mini splits have replaced window units as the affordable option.

Split system — Indoor and outdoor sections are separate, connected by refrigerant lines. Each section independently rated. Choose this for: loads above 5 tons, installations where wall penetration is not possible, or where indoor and outdoor areas have different classifications.

Pressurized system — Positive air pressure keeps hazardous atmosphere out of the building, allowing standard HVAC inside. Choose this for: large buildings where explosion-proofing all interior equipment would be cost-prohibitive. Can save 60–80% on total project cost.

Quick decision guide:

  • Under 3 tons + budget-sensitive → Mini split
  • Under 5 tons + no interior space available → Bard wall-mount (self-contained on exterior)
  • Over 5 tons or no wall opening → Split system
  • Large building + want to minimize XP equipment → Pressurization

Step 5: Consider Environmental Conditions

Beyond classification, think about what else your unit will be exposed to:

Corrosive environments. H₂S (common in refineries and wastewater), salt air (coastal and offshore), acidic atmospheres, or high-humidity conditions will prematurely degrade standard aluminum coils. Coated coils (Aqua-Aero or equivalent) are strongly recommended for these applications. The coating adds modest cost but prevents premature coil failure in the field — where replacement involves hot work permits, crane lifts, and extended downtime in a classified area.

Extreme ambient temperatures. Units are typically rated at standard conditions (95°F outdoor ambient). In desert climates or near process heat sources where ambient temperatures exceed 110°F, capacity de-rating or oversizing may be needed. In cold climates, low-ambient kits may be required for year-round operation.

Vibration. Facilities with heavy rotating machinery or compressors near mounting surfaces may need reinforced mounting provisions. Offshore and marine applications have additional structural requirements.

Altitude. Elevations above 3,300 feet reduce air density, which affects both cooling capacity and motor performance. Applications at altitude may require adjustment to the unit specification.

Step 6: Get a Quote

Once you have your classification, BTU requirement, and inside/outside determination, you have everything you need to get a quote. The fastest path is a phone call.

Call (844) 925-5668

We typically turn around quotes within 24–48 hours. Come with your classification and BTU requirement and we can usually give you a ballpark on the first call.

What to have ready:

  1. Classification — Class, Division, Group
  2. Cooling capacity — BTU or tonnage (or space dimensions + equipment list)
  3. Inside only or full inside + outside
  4. Site conditions — corrosive atmosphere, extreme temperatures, special documentation requirements

Still Figuring Out Your Classification?

Start with the relevant classification page:

Or read our complete guide to explosion-proof air conditioning for the full picture.

Ready to Get a Quote?

Tell us your classification and BTU requirement — we'll have a number back to you in 24–48 hours.

(844) 925-5668

Or request a quote online