Environmental Friendly

Hydrocarbon Refrigerants

Hydrocarbons have become a preferable sustainable natural solution and are already present in various domestic, light commercial, air conditioning, heat pump, or even in medical applications. Minimal investments in components and design changes predestinate them for use in conventional cooling systems originally designed for HFCs.

Summary of topics:

Isobutane (R600a) and Propane (R290)

In chemical terms, hydrocarbon (HC) is an elementary compound composed of hydrogen and carbon that occurs naturally in the environment in crude oil, natural gas, or coal. It is a non-toxic and environmentally friendly alternative to fluorocarbon refrigerants (CFC/HCFC/HFC) which are harmful to the environment since they have been linked to ozone damage and the greenhouse effect. In addition to their environmental benefits, hydrocarbons are cheaper than synthetic refrigerants since they are produced as byproducts of gas and oil. HCs operate at almost the same temperatures as HFCs yet with lower charge. Good thermodynamic and physical properties make HCs an energy-efficient solution.

Low Global Warming Potential (GWP)

Hydrocarbons have a low GWP, zero ODP and, according to safety standard ASHRAE 34, are classified under the group A3 – highly flammable with low toxicity. Since they are flammable with a potential consequence, safety precautions described in various international and national standards must be considered during the design, assembly, operation, and maintenance.

Isobutane (R600a) is widely used in smaller applications such as home refrigerators, freezers, minibars, automotive, and maritime appliances. Propane (R290) on the other hand, is commonly used in commercial refrigeration for food service and retail, merchandisers, heat pump, air-conditioning, and medical applications.

  • KLF – Energy-optimized propane compressor
  • Secop Propane (R290) Compressors
    NLE – Energy-optimized propane compressor
  • Secop Propane (R290) Compressors
    SCE – Energy-optimized propane compressor

History of Refrigerants

Refrigerants have been constantly evolving since their use in refrigeration appliances. Equipment modification, demands for an efficient solution and, in recent years, environmental and safety aspects have moved the development and use forward to new solutions.

In the beginning stages, the use of flammable and toxic fluids was present, but their dangers prevented their wider use. In the early 20th century, chemical non-flammable and low toxic refrigerants came into use and the era of CFCs and HCFCs was rung in. Later in the 1980s, the negative impact of chemical substances on the ozone layer was identified and their use was regulated by the Montreal Protocol. One such substance, chlorine, which is present in CFC and HCFC refrigerants, caused their phase down. Chemical companies identified HFCs as a replacement. While they do not deplete the ozone layer, HFC refrigerants have high global warming potential and contribute to greenhouse gases which can influence climate change.

Kigali Amendment

This has been addressed more recently in 2016 by the Kigali Amendment by a gradual reduction of HFCs by 80–85% by 2050. All valid regulations and efforts for environment protection raised interest for refrigerants with low global warming potential (GWP) and ozone depletion potential (ODP). Among green refrigerants, the use of hydrocarbons (HC) and carbon dioxide (CO2) has increased sharply. Both mentioned have a long history of use since they were used in the early days of refrigeration. Their flammability is today very well covered by safety standards, with proper handling and, within a closed system, hydrocarbons have proven to be a safe alternative to previous refrigerant generations.

Important Dates

  • China, January 2030 – Reduction of HFC emissions by 60% (no specific regulations known by now)
  • China, January 2025 – Reduction of HFC emissions by 25% (no specific regulations known by now)
  • Europe, January 2022 – Ban of HFCs with GWP> 150 in commercial refrigerators and freezers
  • USA, January 2021 – Ban of R134a in automotive A/C
  • USA, January 2020 – Ban of HFCs in all MBP applications and stand-alone LBP systems
  • Europe, January 2020 – Ban of HFCs with GWP> 150 in mobile room A/C
  • Europe, January 2020 – Ban of HFCs with GWP> 2,500 in commercial refrigerators and freezers
  • USA, January 2019 – Ban of HFCs in vending machines & MBP refrigeration systems (<2,200 BTU/h)
  • USA, January 2017 – Ban of HFCs in supermarket systems
  • USA, July 2016 – Ban of HFCs in all retrofit refrigeration systems
  • Europe, January 2015 – Limitation of the HFC quantities for import and production (taxes increase)
  • Europe, January 2015 – Ban of HFCs with GWP> 150 in refrigerator and freezers for domestic usage
  • Worldwide, January 2015 – Complete prohibition of R12 and start of R22 phaseout

R600a as a Replacement of R134a in Residential Refrigerators

  • 1993 launch of the Greenfreeze refrigerator, developed by Greenpeace in cooperation with East German manufacturer Foron (formerly VEB dkk Scharfenstein), proving that R600a, although flammable, cause no problems in a household refrigerator
  • The campaign from Greenpeace has put so much pressure on the traditional manufacturers (Bosch-Siemens, Liebherr, Miele, AEG, Electrolux, Bauknecht) that they decided to accelerate the introduction of R600a and to phase out the recently introduced R134a
  • Also in 1993 Danfoss Compressors (Secop) introduced compressors for R600a
  • More than a billion domestic refrigerators globally used R600a in 2018 (according to UNEP)
  • By 2020, 75% of the global production was based on R600a

Secop (Danfoss Compressors at that time) hydrocarbon-operated compressors from the 1990s

  • Secop TLES5K compressor for R600a from the 1990s
    Secop (Danfoss Compressors) TLES5K for R600a
  • Secop NL11K compressor for R600a from the 1990s
    Secop (Danfoss Compressors) NL11K for R600a

Safety Standards

With the introduction and continuous increase in the consumption of flammable refrigerants, more and more emphasis is being placed on their safety. As a result, they are subject to safety guidelines and legislation. This not only applies to the safe manipulation and use of refrigerants, or protection of persons and property or training, but some standards also specify the maximum allowable charge for different types of applications to assure safe operation. Limits vary between regions and states and must be consulted to assure legal compliance.

What is a standard?

A standard is a formal document to ensure a uniform level of products and services. International standards represent a consensus of national committees and participants that provides guidance on the design, use, production, installation, products, and services. Implementation of international standards by national and regional bodies is voluntary. It is up to each body if adopted in exact wording or with amendments related to the local circumstances. Compliance with relevant standards is up to the component and equipment manufacturer, installer, and service technician.

European and international standards

EN378, the European equivalent to ISO5149, is a general safety standard applicable to refrigerating systems whether stationary or mobile. It relates to safety and environmental requirements in design, construction, installation, operation, maintenance, repair, and disposal of refrigeration systems and heat pumps.

IEC60335-2-89 is the international product safety standard for commercial refrigerating appliances with an incorporated or remote refrigerant unit or compressor. Among others, the standard sets refrigerant charge limits that overrule the requirements of general standard ISO5149. International standards provide a guideline for national standards. In the EU, the standard became EN60335-2-89 and is recognized by all member countries of the European Union. Both are based on the same content and safety requirements, however, EN includes additional requirements of the local market and becomes mandatory if the appliance is placed on European market.

The standard covers appliances such as display and storage cabinets, coolers and freezers, top-counter and under-counter units, blast chillers and blast freezers as well as commercial ice machines. Household, industrial refrigeration, commercial dispensers, vending machines, ice cream makers, laboratory equipment, walk-in cold rooms, devices used in cars, boats and mobile applications are not part of this standard and are covered by their own codes.

International revision including higher charge limits

In 2019, the International Electrotechnical Commission (IEC) released a revision of standard IEC 60335-2-89 which included increased charge limits of flammable refrigerants in self-contained commercial appliances. This was done to facilitate the use of flammable refrigerants and open space for additional appliances in a movement towards green solutions.

The standard covers all safety classes yet with different limits set as 13*LFL (low flammability limit), with a maximum charge of no more than 1.2 kg. For propane and isobutane in safety class A3 it means 500 g and for classes A2 and A2L 1,200 g per one circuit. With the higher charge, additional safety requirements and measures have been defined. Those include hermetical sealing of the cooling circuit, protection of refrigerant-containing parts against accessibility, application construction preventing excessive vibration and appliance marking with the minimum floor area in which it is permitted to be installed.

European update

In Europe, the EN60335-2-89 was updated in August 2022 and currently, harmonization with the Machinery Directive 2006/42/EC is ongoing. Until process finalization and legislation documentation release, the current limit for flammable refrigerants set at 150 g is to be kept and in case of a higher charge need, risk assessment and requirements of general standard EN378 must be followed to assure consideration of all hazards.

The differences in adoption of IEC60335-2-89 by national authorities, different timelines, and different content (adapted to local requirements) could bring difficulties of which one should be applied and which requirement should be fulfilled in terms of sales of the appliances in different territories.

European Union (EU) – Fluorinated Greenhouse Gases (F-Gas) Regulation 517/2014

The F-Gas regulation, in force since 2015, is European directive with the aim to reduce emissions of fluorinated greenhouse gases and protect the environment. To achieve this, the following measures have been set out: the rules and restrictions of the use of F-gases, restriction on placing on the market products that contain F-gases, and their quotas. Regulation intends to reduce emissions by two-thirds by 2030 compared to 2014 levels. HFCs are affected by the regulation due to high global warming potential and are a powerful driver towards low GWP alternatives.

In the refrigeration segment, regulation has brought HFC bans in new and servicing equipment, where less harmful alternatives have been available:

January 2015

  •  Domestic refrigerators and freezer with a GWP of 150 or more

January 2020

  • Hermetically sealed refrigerators and freezers for commercial use with a GWP of 2500 or more (ban of R404A)
  • Stationary refrigeration equipment, that contain or whose functioning relies upon HFCs with a GWP of 2500
  • Prohibition of refrigeration equipment service or maintenance with a charge size of 40 tons of CO2 with a GWP of 2500 or more
  • The prohibition is not applied for reclaimed or recycled HFC gases which are still allowed to be used until January 1, 2030.

January 2022

  • Refrigerators and freezers hermetically sealed for commercial use with a GWP of 150 or more (ban of R134a)
  • Refrigerants below 2,500 GWP are still allowed to be used in appliances not dedicated for commercial use in refrigerators and freezers yet are subjected to available quotas.
  • Refrigerants above 2500 GWP are still allowed to be used with appliances designed to cool products to temperatures below -50°C

The evaluation of the measures taken has demonstrated the success of the regulation in reducing emissions. In April 2022, The European Commission published the regulation of a new proposal which prolongs and tightens the quota system for placing HFCs to the market, introduces a new quota for their production, extends the ban on the use of equipment containing F-gases, strengthens the penalties, or allows automatic customs controls of shipments. It aims to ensure compliance with Montreal Protocol, European Green Deal, and European Climate Law.

The European Parliament revised the proposal and presented its position to regulation changes. The position tightens the placement of F-gas containing products where technologically and economically feasible alternatives exists (including the heat pump sector) and their complete phase down by 2050, proposes stricter deadlines from which it will be no longer possible to place F-gas products on the market regardless of their GWP value.

In May 2023, The European Commission, the European Parliament, and the Council started negotiations to agree on a final wording of the updated regulation. The final document is expected to be issued in Q3/2023 with validity from 2024 onwards.


  • BD Nano direct current isobutane compressor
  • Secop ULT condensing unit
    ULT direct current propane, ethane condensing unit

United States Environmental Protection Agency (EPA) – Significant New Alternatives Policy (SNAP)

The Significant New Alternatives Policy (SNAP) – Refrigeration and Air Conditioning by the United States Environmental Protection Agency (EPA) is a program aimed at evaluating and regulating ozone-depleting substances in various sectors and applications. Following the Montreal Protocol, the use of CFCs has been prohibited since 1989. Additionally, the Kyoto Protocol declared the reduction of HCFCs in 1997. The SNAP program is a part of the Climate Action Plan and makes decisions based on the overall understanding of the environmental and human health impacts as well as its current knowledge about available substitutes. Part of the policy is also the obligation to prohibit the use of a substitute where EPA did find a suitable replacement.

The SNAP program is designed to:

  • identify and evaluate substitutes in end uses that have historically used ozone-depleting substances (ODS);
  • look at the overall risk to human health and the environment of both existing and new substitutes;
  • publish lists of acceptable and unacceptable substitutes by end-use;
  • promote the use of acceptable substitutes; and
  • provide the public with information about the potential environmental and human health impacts of substitutes.

(Source: Environmental Protection Agency)

The SNAP program made an essential step to reduce the risk to human health and the environment by updating the list of affected end uses. A significant step for the industry was the inclusion of the flammable hydrocarbon propane (R290) in the list of acceptable refrigerants for a number of applications, such as self-contained commercial ice machines, water coolers, and ultra-low temperature refrigeration equipment. In addition, the EPA exempted propane from venting prohibition under the Clean Air Act (CAA) section 608, thereby confirming that propane does not pose a threat to the environment since the impact of R290 on air quality is relatively minimal. Even in a worst-case scenario, propane has no greater overall impact on human health and the environment compared to other refrigerants that are listed as acceptable for commercial ice machines, water coolers, and very ultra-low temperature refrigeration equipment.

The EPA regularly reviews substitutes with respect to environmental and health risks. They are classified as acceptable, unacceptable, or acceptable under use conditions. An alternative is considered as an unacceptable substitute if there is another available or potentially available. A list of substitutes by sector is published on:


Propylene and R-443A still listed as unacceptable

The EPA listed propylene (R-1270) as well as the blended refrigerant R-443A as unacceptable alternatives for new cold storage warehouses where leakage of cooling systems is a big problem. The reason behind this listing lies neither in ozone depletion nor in its global warming potential. In addition to these two factors, the EPA also evaluates the potential impacts of propylene and the three components of R-443A on local air quality. The photochemical reactivity of propylene, which is also one of the three components of R-443A, is much higher than that of the other two HCs. This means that propylene as an unsaturated molecule is significantly more reactive in the atmosphere than propane, for example.

The American Innovation and Manufacturing Act (AIM)

The AIM act, in force since December 2020, authorizes the U.S. Environmental Protection Agency (EPA) to manage, reduce, and restrict the use of HFCs, highly potent greenhouse gases, on the U.S. market. The AIM Act results in 85% reduction in production and consumption of high GWP HFC refrigerants by 2036 comparing to 2022 baseline:

  • January 2022: 10% phasedown
  • January 2024: 40% phasedown
  • January 2029: 70% phasedown
  • January 2034: 80% phasedown
  • January 2036: 85% final phasedown

To achieve the objective, three main areas for the EPA to focus on have been identified:

  1. limit and phase down the production and consumption of HFCs (Allowance Allocation Program);
  2. manage HFCs and their substitutes by establishing regulations to control the use and reuse of HFCs, minimize their emissions and maximize their reclamation; and
  3. facilitate the transition to next-generation technologies through sector-based restrictions and limit the use of HFC in specific sectors where lower GWP substitutes are or soon will be available (Technology Transitions Program).

Hydrofluorocarbons (HFCs) are greenhouse gases used by many industries and applications, such as refrigeration, air conditioning, building, fire extinguishing systems, foams, and aerosols. The warming potential of HFCs vary greatly as depending on the chemical composition.

The Final Rule on Phasedown of Hydrofluorocarbons, published by the EPA in October 2023, establishes allowance allocation and restricts the use, sale, installation, distribution, export, and import of higher GWP HFCs in new aerosol, foam, refrigeration, air conditioning and heat pump products, and equipment. It also restricts trade of higher GWP products three years after the restriction date’s entry into force. Restrictions do not apply to any existing product and system in use and the trade of components used to repair existing systems.

The Technology Transitions Program set a maximum GWP limit on HFCs or their blends that are allowed to be used. For some subsectors, EPA has listed specific HFCs or their blends that are restricted in use. Compliance deadlines and GWP limits vary by product and system, as well as by sector and subsector, with a first restriction starting in January 2025 and the last in January 2028. Where a product is defined as functional upon leaving a factory and system is assembled from multiple components and charged on site.

Compliance dates and GWP limits in new self-contained refrigeration, air condition and heat pump for selected products and systems:

January 2025:

  • Stationary residential and light commercial air conditioning and heat pumps, GWP 700
  • Household refrigerators and freezers, GWP 150
  • Vending machines, GWP 150
  • Retail food refrigeration – stand-alone units, GWP 150
  • Motor vehicle air conditioning – light-duty passenger vehicles, GWP 150, Model Year 2025, and no earlier than one year after publication in the Federal Register
  • Refrigerated transport – road and marine self-contained products, prohibited substances R-402A, R-402B, R-404A, R-407B, R-408A, R-410B, R-417A, R-421A, R-421B, R-422A, R-422B, R-422C, R-422D, R-424A, R-428A, R-434A, R-438A, R-507A, R-125/290/134a/600a (55/1/42.5/1.5), RS-44 (2003 formulation), GHG-X5

January 2026:

  • Self-contained automatic commercial ice machines, GWP 150

January 2027:

  • Data centers, computer room air conditioning, information technology equipment cooling, GWP 700
  • Retail food – refrigerated food processing and dispensing equipment with 500 g of refrigerant or less and outside scope of UL621, edition 7, GWP 150
  • Retail food – refrigerated food processing and dispensing equipment with more than 500 g of refrigerant and outside scope of UL621, edition 7, prohibited substances listed in Note 1
  • Self-contained automatic commercial ice machines – batch type with a harvest rate above 1,000 lbs and Continuous type with harvest rate, prohibited substances listed in Note 2

January 2028:

  • Motor vehicle air conditioning – medium-duty passenger vehicles, heavy-duty pick-up trucks, complete heavy-duty vans, GWP 150, Model Year 2028
  • Retail food – refrigerated food processing and dispensing equipment – ice cream makers within the scope of UL621 edition 7, prohibited substances listed in Note 1

Note 1: R-402A, R-402B, R-404A, R-407A, R-407B, R-407C, R-407F, R-407H, R-408A, R-410A, R-410B, R-411A, R-411B, R-417A, R-417C, R-420A, R-421A, R-421B, R-422A, R-422B, R-422C, R-422D, R-424A, R-426A, R-427A, R-428A, R-434A, R-437A, R-438A, R-507A, HFC-134a, HFC-227ea, R-125/290/134a/600a (55/1/42.5/1.5), RB-276, RS24 (2002 formulation), RS-44 (2003 formulation), GHG-X5, Freeze 12
Note 2: R-402A, R-402B, R-404A, R-407A, R-407B, R-407C, R-407F, R-408A, R-410A, R-410B, R-411A, R-411B, R-417A, R-417C, R-420A, R-421A, R-421B, R-422A, R-422B, R-422C, R-422D, R-424A, R-426A, R-428A, R-434A, R-437A, R-438A, R-442A, R-507, R-507A, HFC134a, R-125/290/134a/600a (55/1/42.5/1.5), RB-276, RS-24 (2002 formulation), RS-44 (2003 formulation), GHG-X5, G2018C, Freeze 12

To support compliance with the regulation, all new products and components that use higher GWP HFCs must be labelled and the manufacture or import of such products and components must be reported to the EPA. The label must include the HFC or its blend name, date of manufacture, or at a minimum, the four-digit year, and a refrigerant charge capacity. The harvest rate in self-contained automatic commercial ice machines must be indicated.

As a federal law, the AIM Act applies in all US states. In addition to enacting legislation, some states have enacted their own regulations beyond the EPA SNAP requirements.


The standard specifies safety requirements for the design, construction, and performance of commercial appliances, including requirements for electrical, mechanical and thermal safety. Commercial appliances covered - storage and display of food and beverages in restaurants, grocery and convenience stores, or also ice makers. Compliance with safety standards ensure a safe use and operation of appliances and prevent accidents.

In October 2021, Underwriters Laboratory (UL) released the second edition of safety standard UL60335-2-89 with higher charge limits for A3 (hydrocarbons) and A2L refrigerants which extend their use in commercial applications. The prior limit was 150 g. The maximum allowed refrigerant quantity for commercial stand-alone application depends on the product type and its design.

For open appliances without doors, the charge increased to 13* LFL, which represents 500 g of R290, and for closed appliances with doors or drawers to 8*LFL what is 300 g of R290.

When it comes to A2L refrigerants, allowed or proposed for use in full or under the certain conditions in precisely specified applications, there are several refrigerants such as R32, R1234yf, R454A, R454B, R454C, R455A, R516A, R1234ze(E). Since the group covers a wide range of refrigerants, the maximum charge limits are not set but must be calculated based on the refrigerant characteristics and equipment design – open or closed with doors or drawers.

With a charge increase, specific requirements addressing the safe use of flammable refrigerants have been determined. Those focus on leakage preventing design – hermetically sealed systems, corrosion-resistant materials, joint construction, the use of leak detection equipment and adequate ventilation to mitigate hazardous concentrations, ignition source control and use of safety features, flame-retarding covers, or spark-free components. Equipment using flammable refrigerants must be marked with a label informing the refrigerant type, charge amount, and appropriate safety warnings.

Second edition of UL60335-2-89, based on international IEC60335-2-89:2019, covers all current market changes and facilitate access to the global market. To be harmonized with the latest edition, standards for commercial refrigeration appliances and ice maker (listed below) to be replaced by UL60335-2-89:

  • UL412 - Refrigeration Unit Coolers
  • UL471 - Commercial Refrigeration Equipment which allowed 150g of A3 and 500g of A2L
  • UL427 - Refrigerating Units
  • UL563 – Ice Makers
  • UL1995 – Heating and Cooling Equipment
  • CSA c22.2 No. 120 – Refrigeration Equipment

This means, that after September 29, 2024, all new equipment previously covered by mentioned standards will need to comply with and be certified according to UL60335-2-89.

Application certification is done based on the above-mentioned standards will remain valid until the next technical re-evaluation, which must comply with the requirement UL60335-2-89.

Implementation of appliances with higher charges of flammable refrigerants on the U.S. and Canada market must follow regulations and policies such as EPA SNAP, Ashrae 15 or State and Local Building Codes, which need to approve and incorporate the updates of UL60335-2-89 in the second edition and use of flammable refrigerants.

  • KLF – Energy-optimized propane compressor, 115–127 V, 60 Hz
  • Secop SCE15MNX Propane Compressor
    SCE – Energy-optimized propane compressor, 103–127, 60 Hz

Refrigerants – Natural, Semi-Natural, Synthetic, and Blends

Refrigerant is a fluid that transfers heat in a refrigeration system and cools the contents. Based on the chemical composition, refrigerants are divided into groups:

  • CFC – chlorofluorocarbons (R12)
  • HCFC – hydrochlorofluorocarbons (R22)
  • HFC – hydrofluorocarbons (R134a, R404A)
  • HFO – hydrofluroolefins (R1234yf)
  • HC – hydrocarbons (R290, R600a)

Different chemical compositions have different impacts on the environment. Certain chemical substances present not only in refrigerants have been identified as harmful to the environment since they decompose the stratospheric ozone layer and create a greenhouse effect. Two properties, the Ozone Depletion Potential (ODP) and the Global Warming Potential (GWP) are the main two measurable categories for monitoring changes in the atmosphere and air quality.

GWP is the measure of a refrigerant’s ability to trap heat in the atmosphere over a given period compared to carbon dioxide. The higher value of GWP contributes to greater global warming.

ODP is the measure of a refrigerant’s ability to destroy ozone molecules in the upper atmosphere. The lower the ODP value, the less damaging the refrigerant is to the ozone layer.

A number of regulations came into force to eliminate the use of environmental hazardous substances and reduce total electrical energy consumption.

The Montreal Protocol, in force since 1987, is a global environmental agreement that regulates the production and consumption of chemicals responsible for ozone depletion. One of those, chlorine, present in the refrigerant groups CFC or HCFC, caused their phase down.

Hydrofluorocarbon refrigerants developed to replace stratospheric ozone-depleting substances CFC and HCFC have an ODP value of zero or close to zero. Although HFC’s do not harm the ozone layer, they have high global warming potential as they contribute to greenhouse gases which influence climate change. This fact was discovered after the Montreal Protocol was adopted and was recently covered by a Kigali Amendment in force since January 2019. Those countries that ratified the Kigali Amendment agreed on the gradual reduction of fluorinated greenhouse gases (HFCs).

With the prohibition of CFCs, HCFCs, and HFCs three possible choices in the refrigeration segment were left: HFC-HFO blends, HFOs, and natural refrigerants such as hydrocarbons (HCs).


Odorless compounds of hydrogen and carbon, occur naturally in the environment. Compared to synthetic refrigerants, they are environmentally friendly, harmless with zero ODP, and have a very low GWP. HCs operate at almost the same temperatures as HFCs and with a lower charge. Good thermodynamic and physical properties make HCs an energy-efficient solution. The downside is their flammability and higher demand for safety (safety class A3).

Secop has been an early adopter of hydrocarbons as a refrigerant and believes the most efficient and economical friendly substances for use in cooling appliances are isobutane (R600a) and propane (R290).

Due to cooling capacity limitations, R600a is recommended for use in smaller applications such as home refrigerators and freezers, minibars, and wine coolers. It is also applicable for mobile cooling use, including refrigerators and freezers for the automotive and maritime industries, cooling portable boxes, and products with solar and/or battery supply.

Refrigerant R290 with its efficiency is a good fit for light commercial appliances in food service and food retail, coolers, freezers, merchandisers, supermarket appliances as well as in the growing medical segment.

R600a and R290 with their efficiency and depending on the system design, require 40-50% smaller quantity of refrigerant compared to other refrigerants. Due to their flammability and explosive properties, the refrigerant volume is limited by standards and can vary from region to region. With proper precautions and care, there is no reason to worry about them. Minimal investments in components and design changes predestinate them for use in conventional cooling systems originally designed for HFCs.


(HFO), as HFCs, chemically consist of hydrogen, fluorine, and carbon but with a relatively low GWP and with zero impact on the ozone layer are more environmentally friendly. HFOs do not trap heat in our atmosphere and do not contribute to global warming. However, they are classified as mildly flammable, have a safety class of A2L, and are laden with environmental and human health concerns. A typical representative is R1234yf that has already been approved by Secop for use in car air conditioning system, minibars, or truck refrigerators,.

HFC/HFO blends

are combination of HFC and HFO refrigerants and provide similar performance as HFCs yet with a lower environmental impact. Many have a temperate glide and were developed to replace HFC refrigerants. Verification of alternative refrigerants in existing Secop compressors was performed. R452A, R449A, R448A were approved as replacements to R404A/R507, and R513A approved as a replacement of R134a for certain models. Lower cooling performance, higher energy consumption, higher operating pressures and temperatures, and limitations in operation were observed. With proper system optimization, they can operate reliably for years. LBP operation is not recommended at all with R448A and R449A due to very high internal temperatures during normal load conditions. The blends previously mentioned are assigned to different safety groups: R513A, R452A, R449A and R448A are classified under safety group A1 (non-flammable), whereas R454C, R455A are classified as A2L (mildly flammable).

Secop Product Bulletins

Flammable Refrigerants

A refrigerant is a flammable gas and, in contact with an ignition source (electrical sparks, flame, static electricity), could ignite or burn and cause a fire. Lower (LFL) and upper (UFL) flammability limits determine the substance’s ability to produce a flame under a specific condition. These limits specify the concentration range in which the substance is flammable in the air. Below the LFL, the concentrations are too lean to burn or explode, above the UFL the concentrations are too rich or lack the oxygen to burn or explode. The risk of fire from a refrigerant is low when properly handled, used, and stored. Users, manufacturers, installers, and all other persons who come in contact with flammable refrigerants need to respect the safety rules.

Flammable refrigerants have low global warming potential, zero ozone depletion potential, are widely available, and inexpensive. Although flammable, they are widely used in refrigerating and air conditioning equipment due to their energy and cost efficiency, and high quality.

Typical flammable refrigerants used with light commercial and household appliances are R290 and R600a or R1234yf used in car air conditioning system, minibars, and truck refrigerators.


Key flammable properties of refrigerants:
Refrigerant R600a R290 R1234yf
Lower flammability limit 1.5% by vol.
(38 g/m3)
2.1% by vol.
(39 g/m3)
6.5% by vol.
(72 g/m3)
Upper flammability limit

8.5% by vol.
(212 g/m3)

9.5% by vol.
(171 g/m3)

12.3% by
(135 g/m3)vol.

Auto ignition temperature 460°C 470°C 405°C


ASHRAE 34 or ISO 817 classify refrigerants to safety groups based on their flammability and toxicity:
  Safety Group
Higher flammability A3 B3
Flammable A2 B2
Lower flammability A2L B2L
No flame production A1 B1
  Lower toxicity Higher toxicity


The main difference between A2 and A2L, respectively B2 and B2L, is the refrigerant’s ability to produce a flame. Refrigerants in the *L group will burn, but their burning velocity is below 10cm/s which is lower than A2 or A3. They are difficult to ignite and self-extinguish.

All flammable refrigerants require system design and operations to follow the safety precautions. They can be used in new installations only and cannot be considered as drop-in alternative to existing HFCs systems. Electrical equipment has to comply with the IEC/EN 60079-15 standard, must be spark-free, or protected by an enclosure.

To prevent fire hazards caused by flammable refrigerants, relevant standards have been adopted to limit the charge size. They vary between regions and states and must be consulted to assure a legal requirement. If a higher charge is required, a risk analysis must be performed to identify and analyze all potential risks and prove the safety of the product. Charge quantity and ignition sources in place of application installation must be taken into consideration.

Safety standards such as ISO5149 or EN378 set requirements for the design, manufacture, installation, and operation of systems using flammable refrigerants with the aim of minimizing the risk of explosions.

Secop compressors for flammable refrigerants are marked with a yellow warning label even if they contain no refrigerant when leaving the factory.

Refrigerant charge

Charging refrigerants should be done carefully and accurately. It can be done by weight or volume. In case of flammable refrigerants, it is recommended to use the weighing method as the charge quantity is low. The type of refrigerant and its quantity is stated by the refrigerator manufacturer on the label, datasheet, catalog, or other documentation. The optimal charge quantity is detected during testing under normal running condition and standard environment.

Currently valid European legislation EN60335-2-89 limits the maximum amount of refrigerant, allowed in a product to reduce flammability hazards and risk of toxicity to 150g. With this quantity it is possible to cover most plug-in commercial applications – merchandisers and food retail. Remote systems do not fall under the scope of this standard but follow EN378 with different criteria, no charge limits yet with other defined safety regulations.

HC charge increase

International Electrotechnical Commission (IEC) with its latest revision of the global safety standard IEC60335-2-89 from 2019 allows a higher charge of flammable refrigerants in self-contained commercial refrigeration appliances. Movement towards an ecological solution coupled with demands on higher charges prompted the charge increase allowance. The standard is voluntary and will come into force only when adopted and integrated by the regional bodies.

The revision covers all safety classes but with a different limit which changed to 13*LFL. For the single circuits, charge limits increased from 150 g to 500 g for refrigerants in safety class A3 (R290, R600a) and from 150 g to 1200 g for safety class A2 and A2L (R1234yf, R454C, R455A). The standard covers appliances such as display and storage cabinets, coolers and freezers, top-counter and under-counter units, blast chillers and blast freezers as well as commercial ice machines. All other appliances such as vending machines, ice cream makers, laboratory equipment, and household refrigeration comply with their own standards.

The new revision also defines additional safety requirements and measures when higher charges are used so as to not create more risk for the user. This includes hermetical sealing of the cooling circuit, protection of refrigerant containing parts against accessibility, application construction preventing excessive vibration, and appliance marking with the minimum floor area in which it is permitted to be installed.

Installation and service

Installation, service, and repair of systems with flammable refrigerants is to be conducted by properly trained personnel. This includes knowledge of tools, transportation of compressor and refrigerants, and the relevant regulations and safety precautions.

During service, possibility of refrigerant release or leak is present. Any potential sources of ignition should be eliminated, and the space should be properly vented by air or using a ventilation fan. Area should be marked with a warning symbol and monitored with a leak detector designed for a specific refrigerant to ensure the refrigerant concentration does not exceed the limits. Fire extinguishers must be available in the room. Personal protective equipment (PPE), gloves, goggles, and cloths are always needed.

Conversions of existing system from HCFC and HFC to R600a and R290 is not allowed, since the system is not approved for operation with flammable refrigerants and electrical safety has also not been tested according to current standards.

Compressor Service for R600a, R290 – Step by Step

Secop teams up with VULKAN Lokring – manufacturer of solder-free tube connections for the refrigeration and air-conditioning industry to deliver a educational film "Compressor Service for R600a, R290 – Step by Step". Servicing and repair for R600a and R290 systems is possible for skilled and well trained service technicians.

Secop Application Guideline for R600a and R290