Refrigerant Classification, Properties, and Substitution: A Practical Guide for Industrial Cooling and Agricultural Climate Control

Choosing a refrigerant is no longer a matter of comparing cooling capacity alone. For an industrial chiller, food-processing line, cold store, or controlled-environment farm, the refrigerant affects system design, safety, energy use, maintenance, and future equipment availability. A low global warming potential (GWP) is valuable, but it does not make a fluid suitable for every compressor, room, or operating temperature.

This guide explains refrigerant classification and properties, then turns that knowledge into a practical selection process. It also shows why refrigerant substitution usually requires an engineered retrofit—or a new system—rather than a simple change of charge.

How Are Refrigerants Classified?

Chemical families: HCFCs, HFCs, HFOs, and natural refrigerants

Refrigerants are often grouped by chemical family:

HCFCs, such as R22, contain chlorine and have ozone-depletion potential. They are legacy fluids, not a sensible starting point for a new system.
HFCs, such as R134a, R404A, R410A, and R32, have zero ozone-depletion potential but can have substantial GWP.
HFOs, such as R1234ze(E), generally have much lower GWP. Some are classified as mildly flammable and require equipment designed for that classification.
Natural refrigerants include ammonia (R717), carbon dioxide (R744), and propane (R290). Their environmental profiles can be attractive, but each presents a different engineering challenge.

These labels describe chemistry, not overall suitability. A refrigerant that works well in a packaged chiller may be inappropriate for a large food-processing plant or an occupied growing room.

Single fluids, blends, and temperature glide

A single-component refrigerant has one defined chemical composition. A blend contains two or more components. Some blends exhibit temperature glide: their temperature changes during evaporation or condensation even when pressure is effectively constant.

That distinction matters during heat-exchanger selection, pressure-temperature checks, and charging. A technician cannot assume that a blend behaves like the refrigerant it replaces. The equipment manufacturer’s service instructions, including the appropriate bubble-point and dew-point data, must govern the work.

Safety classes and what they mean

Refrigerant safety classifications describe toxicity and flammability. In broad terms, A indicates lower toxicity and B higher toxicity; the number and any “L” designation describe flammability characteristics. For example, R744 is A1, R454B and R1234ze(E) are A2L, R290 is A3, and R717 is B2L.

A classification is a design input—not permission to use a fluid anywhere. The allowable charge, installation location, ventilation, detection, electrical equipment, and applicable local standards must be assessed together.

Which Refrigerant Properties Matter Most?

GWP, ozone impact, and leakage

GWP compares the warming effect of a released gas with carbon dioxide over a specified period. A high-GWP system with repeated leaks can have a substantial direct climate impact. Ozone-depletion potential is a separate measure: a fluid may have zero ozone-depletion potential yet still have high GWP.

Published GWP numbers can differ because reference periods and assessment methods differ. When comparing proposals, ask suppliers to state the GWP basis they used. More importantly, compare refrigerant charge and expected leakage alongside GWP; a fluid’s rating alone does not describe the emissions of an installed system.

Pressure, temperature, and compressor fit

The refrigerant’s pressure-temperature relationship influences compressor selection, pipework, controls, and heat-exchanger design. R744, for example, calls for equipment designed for its distinctive high-pressure operation. A refrigerant with a similar application label to an existing fluid is not necessarily compatible with existing hardware.

Selection must begin with the actual duty: required cooling capacity, evaporating temperature, heat-rejection conditions, operating hours, and part-load profile. A cold store, a process chiller, and a greenhouse dehumidification system impose different loads even when all three are described as “cooling.”

Energy efficiency is a system result

A refrigerant does not carry a fixed coefficient of performance (COP) into every installation. Efficiency belongs to the complete system: compressor, heat exchangers, controls, ambient conditions, and operating schedule.

Ask for performance data at your site’s design point and representative part-load conditions. A comparison based only on nameplate capacity or a single laboratory rating can miss the conditions that dominate annual electricity use.

Common Refrigerants at a Glance

Refrigerant	Family and safety class	Useful starting point	Main design question
R404A	HFC blend; A1	Existing refrigeration equipment	Is continued service or replacement economical under local rules?
R134a	HFC; A1	Existing medium-temperature systems and chillers	What approved lower-GWP options fit the equipment and duty?
R513A	HFC/HFO blend; A1	Some R134a-system evaluations and new chillers	Has the equipment maker approved the proposed use?
R454B	HFC/HFO blend; A2L	Equipment designed as an alternative to R410A	Can the installation meet A2L safety requirements?
R1234ze(E)	HFO; A2L	Selected purpose-designed chillers	Do the compressor and system design meet the duty?
R717	Ammonia; B2L	Industrial refrigeration	How will the design manage toxicity and plant-room safety?
R744	Carbon dioxide; A1	Cold-chain, cascade, and other engineered systems	Can the high-pressure system meet site conditions efficiently?
R290	Propane; A3	Suitable purpose-designed packaged equipment	Are charge and flammability controls appropriate?

This table is a screening tool, not a list of interchangeable fluids. It is particularly important not to interpret a proposed alternative to R410A or R134a as an automatic field retrofit.

What Is Changing in Refrigerant Regulation?

The Kigali Amendment establishes a global HFC phase-down, but individual markets follow their own schedules and equipment rules. Exporters therefore need to check the destination market, product category, and placement-on-the-market date before finalizing a design.

In the European Union, Regulation (EU) 2024/573 replaced the earlier F-gas regulation. Its restrictions are equipment-specific, not one universal GWP ceiling. For stationary chillers, the regulation sets a 2027 restriction at GWP 150 or more for units rated up to 12 kW, and at GWP 750 or more for units above 12 kW, subject to stated safety exceptions. Other refrigeration equipment and heat pumps have different provisions.

For buyers, the practical question is not simply, “Is this refrigerant legal?” It is: “Is this exact equipment configuration suitable for our application and destination market on the planned sales date?” Existing-equipment servicing also needs separate review rather than being inferred from a rule for newly placed equipment.

How to Choose by Application

Industrial manufacturing and process chillers

Start with process requirements, not a preferred refrigerant name. Record supply and return temperatures, peak and minimum loads, operating hours, ambient conditions, and the cost of downtime. A process that runs continuously may justify a different efficiency and redundancy strategy from one that operates only during a production shift.

Where a liquid distribution loop is practical, a chiller can keep the primary refrigerant within a defined equipment area while chilled water or another suitable secondary fluid serves the process. This does not remove the need for refrigerant safety design, but it changes where refrigerant-containing components are located.

Food processing and cold-chain storage

These facilities often contain several temperature zones and operate for long periods. Evaluate door openings, product pull-down loads, defrost cycles, heat recovery opportunities, and what happens if one compressor fails.

For a large installation, ammonia or an ammonia/CO₂ architecture may be worth evaluating. For other sites, a different engineered solution may better match staffing, space, and maintenance capability. The right comparison includes annual energy use, refrigerant charge, service access, and resilience, not purchase price alone.

Greenhouses and indoor growing rooms

Agricultural climate control adds a requirement that conventional cooling comparisons can overlook: moisture removal. Plants transpire, so a system must manage both sensible heat and latent load. A room can reach its temperature setpoint while remaining too humid for the crop strategy.

Ask the design team to document crop stage, lighting schedule, irrigation pattern, target temperature and humidity, airflow, and the need for heat recovery or reheat. Compare equipment at daytime and nighttime conditions. In a sealed growing space, controls must coordinate cooling and dehumidification rather than letting two independent devices work against each other.

A Safer Refrigerant Substitution Workflow

A refrigerant substitution should be treated as an engineering decision with a documented approval path.

Identify the existing system. Record the equipment model, refrigerant, charge, compressor, lubricant, seals, expansion device, design pressures, and operating temperatures.
Define the real objective. Is the problem leakage, supply risk, operating cost, an equipment failure, or a new-market requirement? The answer determines whether servicing, retrofitting, or replacement deserves priority.
Shortlist approved options. Check manufacturer guidance and the rules for the installation location. Do not assume that a candidate with similar pressures is an approved substitute.
Model performance and safety. Review capacity, discharge temperature, lubricant and material compatibility, charge, ventilation, detection, and expected operation at part load.
Plan the work. Specify recovery of the old refrigerant, required component or control changes, commissioning tests, labels, technician training, and future service documentation.
Verify the result. After commissioning, compare measured temperatures, pressures, power, and control stability with the agreed performance targets.

Never add a new refrigerant to an existing charge or treat a new safety class as a routine refill. If the conversion cannot be supported by the equipment maker and a qualified design review, replacement may be the safer long-term choice.

Calculate Lifetime Impact, Not Just GWP

Here is a useful way to challenge a shortlist: compare direct emissions from refrigerant losses with indirect emissions from electricity consumption. Then add installation cost, maintenance, downtime exposure, and end-of-life recovery to the business case.

Consider two proposed chillers. One uses a very-low-GWP refrigerant but consumes more electricity at the site’s common part-load condition. The other has a higher-GWP charge but lower modeled annual power consumption and a tightly controlled leak-management plan. The first option is not automatically the lower-impact choice; the result depends on actual charge, leakage, operating hours, and the electricity supply.

Request the same assumptions from every bidder. A decision table should show design and part-load performance, total charge, applicable safety measures, service requirements, and the refrigerant’s regulatory outlook. This makes proposals comparable and exposes gaps before procurement.

Questions to Ask a Cooling-System Supplier

Before signing off on an industrial refrigeration or agricultural climate-control project, request:

A load calculation covering peak and representative operating conditions.
The refrigerant designation, safety class, charge, and GWP reference basis.
Performance data at your specified temperatures and ambient conditions.
A drawing showing refrigerant-containing equipment and occupied areas.
The proposed leak-detection, ventilation, alarm, and emergency strategy.
A controls sequence covering part load, faults, and—where relevant—dehumidification.
A commissioning plan, maintenance schedule, and refrigerant recovery procedure.
Written confirmation of equipment compatibility and destination-market requirements.

These documents turn a refrigerant discussion into an auditable equipment decision. They also give operators a clearer basis for comparing energy performance after installation.

Build the Right System for the Site

The best refrigerant is not necessarily the one with the smallest GWP number. It is the one incorporated into a safe, efficient, maintainable, and market-appropriate system for the actual cooling duty.

Zhejiang Kingfit Environment Co., Ltd. develops industrial refrigeration and intelligent agricultural environmental-control solutions. Share your facility type, location, temperature and humidity targets, cooling load, operating schedule, and existing equipment details with the Kingfit team. Those inputs provide a practical starting point for discussing a new system or a technically justified upgrade.

Frequently Asked Questions

Can R290 replace R22 in an existing chiller?

Do not assume so. R290 is an A3 refrigerant. An existing chiller must not be converted simply because its original refrigerant is becoming harder to source. Obtain equipment-maker approval and a qualified assessment of compatibility, charge, ignition risks, and applicable rules.

Is R513A a drop-in replacement for R134a?

Not automatically. R513A is an A1 alternative considered for some applications, but suitability depends on the specific equipment and operating duty. Check manufacturer instructions and required changes before any retrofit.

Is CO₂ always the best option for a cold store?

No. R744 can be a strong candidate, but its high-pressure design and performance under local ambient conditions need evaluation. Compare complete architectures, not refrigerant names alone.

Does lower GWP guarantee lower operating cost?

No. Electricity use, system design, leakage, maintenance, and operating hours affect lifetime cost. Compare proposals using the same site conditions and measurement assumptions.

Why does an indoor farm need dehumidification if it has cooling?

Cooling controls temperature; crop transpiration adds moisture. Some cooling removes moisture, but capacity and control may not match the grow room’s changing latent load. Specify both temperature and humidity performance.

Are EU refrigerant limits the same for every chiller and heat pump?

No. Rules differ by equipment type, capacity, date, and applicable exceptions. Confirm the classification of the proposed product before relying on a GWP threshold.

References

1. EVROPROM – “Refrigerants: Classification, Properties, Substitution, and Environmental Trends” – Original article reviewed for the rewrite. https://evroprom.com/news/refrigerants-classification-properties-substitution-and-environmental-trends/

2. European Union – “Regulation (EU) 2024/573 on fluorinated greenhouse gases”, particularly Annex IV on equipment restrictions. https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32024R0573

3. European Commission – “Air conditioning: Climate-friendly alternatives to F-gases” – Equipment categories, chiller provisions, refrigerant GWP values, and safety groups. https://climate.ec.europa.eu/areas-action/fluorinated-greenhouse-gases/climate-friendly-alternatives-f-gases/air-conditioning_en

4. ASHRAE – “Refrigerant Designations” – Refrigerant names, blend compositions, and information about Standard 34 classifications. https://www.ashrae.org/technical-resources/standards-and-guidelines/ashrae-refrigerant-designations

5. UNEP Ozone Secretariat – “Kigali Amendment to the Montreal Protocol” – International HFC phase-down context. https://ozone.unep.org/kigali-amendment-overview

6. Resource Innovation Institute – “HVAC Best Practices Guide for Controlled Environment Agriculture Operations” – Cooling, humidity, airflow, controls, and crop-environment design considerations. https://resourceinnovation.org/wp-content/uploads/2022/06/RII-HvacBPG-2022-v4-1.pdf

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