NH₃ vs CO₂ in industrial refrigeration
Understand, compare, choose
Faced with growing demands in terms of performance, regulatory compliance and environmental responsibility, industrial plant managers today need to master the technical and economic challenges of refrigeration systems.
This decision, far from being purely technical, has a direct impact on the company's operating profitability, plant safety and carbon footprint.
Quick access to technical data
NH₃ or CO₂? Keys to choosing yournatural refrigerant
The choice of refrigerant is a strategic decision for any industrial refrigeration plant. Two solutions predominate in industry today: ammonia (NH₃) and carbon dioxide (CO₂). Both are considered “natural” fluids – i.e. with low environmental impact – but they have distinct technical, economic and regulatory characteristics.
In Quebec and Canada, where industry is facing increasing challenges in terms of energy performance, safety, compliance and sustainable development, understanding the differences between NH₃ and CO₂ is essential for guiding technological choices.
Physico-chemical properties
Ammonia (NH₃)
- Chemical formula: NH₃
- Boiling temperature: -28°F (-33.3°C) at atmospheric pressure
- High cooling capacity by mass (high cooling capacity)
- Non-miscible with oil, requires specific oil return management
- Colorless, characteristic pungent odor: detectable at very low concentrations
Carbon dioxide (CO₂, R744)
- Chemical formula: CO₂
- Boiling temperature: -109.3°F (-78.5°C) (sublimation), but used in liquid/gas form under controlled conditions (transcritical or subcritical circuit)
- High density for compact installations
- Miscible with suitable oil
- Odorless, colorless: detection by concentration sensors
Safety and risk management
NH₃: effective, but toxicological risk
- Toxicity: ammonia is toxic to humans at low concentrations (TWA Québec: 25 ppm, STEL: 35 ppm).
- Flammability: slightly flammable from 15-28% in air (class B2L)
- Easy to detect: strong odor, quick leak detection
- Regulated management: strict protection standards, ventilation, training, emergency plans
CO₂: increased safety, but beware of asphyxiation
- Non-toxic at usual concentrations, but risk of asphyxiation at high concentrations (gas heavier than air).
- Non-flammable (Class A1)
- Sensor-only detection
- Very high operating pressures: robustness and equipment certification requirements (up to 1764 psig (120 bar) in transcritical operation)
Energy performance
NH₃: excellence for performance and extreme cold
- High coefficient of performance (COP), especially at low temperatures
- Excellent efficiency for high-capacity installations (cold stores, food processing industries, processing)
- Suitable for prolonged operation and load variation
CO₂: flexibility and performance, even in cold climates
- Highly efficient for medium-temperature applications (commercial refrigeration, supermarkets, logistics warehouses)
- In transcritical mode, the COP can be lower than NH₃ in hot weather, but in Quebec’s climate, performance is very competitive.
- Compact systems: easy to adapt in urban areas or confined spaces
Environmental issues
NH₃ and CO₂: responsible choices
- Global warming potential (GWP):
NH₃ = 0,
CO₂ = 1 (reference) - Non-destructive of the ozone layer
- Both favored by regulations (Montreal Protocol, F-Gas), unlike HFC/HFO
Specific regulatory constraints
- NH₃: strict obligations on storage, ventilation, operator training, emergency plans (CNESST, CSA B52, etc.) need for certification of high-pressure equipment depending on sector.
- CO₂: need for certification of high-pressure equipment, suitable detection and ventilation protocols.
Regulations specific to Quebec: requirements, obligations and differences by fluid
In Quebec, regulatory oversight of refrigeration systems is particularly rigorous, for both ammonia (NH₃) and carbon dioxide (CO₂). Companies must comply with a patchwork of laws, regulations and technical standards designed to protect the health and safety of the public, workers and the environment.
NH₃ (Ammonia) regulations in Quebec
- Act respecting occupational health and safety (AOHS) and Regulation respecting occupational health and safety (RROHS): As ammonia is classified as a hazardous substance (toxicity, flammability), all installations must be subject to a risk analysis, an emergency measures plan, and specific signage.
- CSA Code B52 (Mechanical Refrigeration Code), applicable in the province, imposes increased requirements on :
- Design and installation (distance from populated areas, ventilation requirements, materials)
- Ammonia leak detection (automatic systems, alarms, periodic maintenance)
- Containment and consequence limitation protocols in the event of a leak
- CNESST (Commission des normes, de l’équité, de la santé et de la sécurité du travail): Mandatory inspection of pressure installations, operator training, incident reporting.
- Emergency plan: Facilities of a certain size must file an emergency plan with local authorities (municipality, fire department).
CO₂ (Carbon Dioxide) regulations in Quebec
- CSA Code B52 also applies to CO₂, with specific requirements on equipment robustness (certified high-pressure equipment), ventilation of technical rooms, and drain management.
- Asphyxiation risks: As CO₂ is heavier than air, concentration detectors and suitable ventilation systems are required in enclosed premises.
- Inspection of pressure equipment: even though CO₂ is non-toxic and non-flammable, installations operating at high pressure must be declared to the RBQ (Régie du bâtiment du Québec) and inspected periodically.
Document management and traceability
- For both fluids, it is mandatory to keep up-to-date: Inspection and maintenance records, Leak and intervention reports, Operator training documentation, Equipment compliance and certification records.
Soteck Clauger tip:
The use of a digital portal such as MyPortal 3E greatly facilitates document management, preparation for CNESST/RBQ inspections, and responsiveness in the event of an audit or incident report.
Summary of regulations
- NH₃: Much heavier and restrictive regulations (due to toxicity), increased training requirements, emergency planning and risk management.
- CO₂: Regulations focused on pressure equipment and asphyxiation prevention, similar documentation requirements but working environments perceived as less risky.
Summary table
| CRITERIA | NH₃ (Ammonia) | CO₂ (Carbon dioxide) |
|---|---|---|
|
Security |
Toxicity, emergency plans, mandatory training, detection, evacuation plans |
Risk of asphyxiation, CO₂ detection, ventilation mandatory |
|
Quebec regulations |
Very strict: CNESST, CSA B52, emergency plan, incident reporting, RBQ |
CSA B52, RBQ, pressure equipment control, ventilation management |
|
Document management |
Mandatory, leak register, inspections, training |
Mandatory, inspection and maintenance log |
|
Other bonds |
Submission of municipal response plan, risk analysis, containment measures |
Declaration of pressure equipment, periodic inspection |
Investment and operating costs
NH₃: initial investment, but fast ROI
- Higher installation costs (safety features, training, advanced automation)
- Specific maintenance (oil management, seal monitoring)
- Long plant life and low fluid costs
- Attractive ROI on high-load refrigeration systems (sometimes <3 years)
CO₂: competitive and scalable
- Compact systems, fast installation, competitive costs for medium to large installations
- Easy maintenance (no toxicity, standardized technology)
- Low fluid costs, but more expensive pressurized equipment
- Ideal for extending or modernizing existing sites
Innovation, supervision and digitization
Digitization of installations (monitoring, predictive maintenance, document management) is now a key differentiating factor.
Integrating tools like MyPortal 3E offers the same added value for tracking, optimization and compliance, whether your choice is NH₃ or CO₂.
- For NH₃: enhanced incident supervision, emergency plan management and traceability of critical maintenance.
- For CO₂: precise monitoring of transcritical cycles, optimized consumption, easier document management
In short: choose according to your challenges and constraints
| CRITERIA | NH₃ (Ammonia) | CO₂ (Carbon dioxide) |
|---|---|---|
|
Security |
Highly regulated, toxic |
Secure, but beware of asphyxiation |
|
Energy efficiency |
Excellent, especially in very cold weather |
Very good, flexible, efficient in Quebec |
|
Installation cost |
Higher, faster ROI |
Moderate to high flexibility |
|
Maintenance |
Specific, training required |
Standardized, less restrictive |
|
Environment |
GWP = 0 |
GWP = 1, no impact Ozone |
|
Regulations |
Very strict (emergency plans, etc.) |
Specific (pressure, detection) |
|
Adaptability |
Large installations |
Small/medium/large, urban |
|
Digitalization (MyPortal 3E) |
Optimizing safety and compliance |
Performance and compliance monitoring |
In conclusion
In Quebec, the choice between NH₃ and CO₂ must imperatively integrate regulatory constraints: ammonia, although highly efficient, requires exhaustive risk management, careful documentation and constant vigilance.
CO₂, on the other hand, is attractive for its less restrictive regulations on the toxicity aspect, but requires technical expertise in high-pressure and confined-atmosphere management.
Whether you opt for NH₃ or CO₂, compliance, security and document management are essential to ensure the longevity of your facilities. Digital tools such as MyPortal 3E are now valuable allies in keeping up with Quebec standards at all times.