Refrigerant Evaluator Tool

A1 Safety Classification is the safest available safety classification. The refrigerants within this classification are non-toxic and do not have flame propagation at 140°F and thus are deemed non-flammable.

A2 Safety Classification is for refrigerants that are non-toxic but have flame propagation at 140°F. However, these refrigerants have relatively high Lower Flammability Limits (LFL) (>0.0062 lb./cu. ft.), and low heat of combustion (< 8,169 BTU/lb.). Because the heat propagation velocity is not relatively low, these refrigerants are classified as flammable.

A2L Safety Classification is for refrigerants that are non-toxic but have flame propagation at 140°F. However, these refrigerants have relatively high Lower Flammability Limits (LFL) (>0.0062 lb./cu.ft.), low heat of combustion (< 8,169 BTU/lb.) and low heat propagation velocity (<3.9 in./sec.). These are deemed to be mildly flammable.

A3 Safety Classification is for refrigerants that are non-toxic but have flame propagation at 140°F. These refrigerants have relatively low Lower Flammability Limits (LFL), high heat of combustion (> 8,169 BTU/lb.) and the heat propagation velocity is not relatively low. Therefore, these refrigerants are classified as highly flammable.

B1 Safety Classification is for refrigerants that have higher toxicity but do not have flame propagation at 140°F and thus are deemed non-flammable, but toxic.

B2 Safety Classification is for refrigerants that have higher toxicity and have flame propagation at 140°F. However, these refrigerants have relatively high Lower Flammability Limits (LFL), and low heat of combustion. Because the heat propagation velocity is not relatively low, these refrigerants are classified as flammable and toxic.

B2L Safety Classification is for refrigerants that have higher toxicity and have flame propagation at 140°F. However, these refrigerants have relatively high Lower Flammability Limits (LFL), low heat of combustion and low heat propagation velocity. These are deemed to be mildly flammable, but toxic.

B3 Safety Classification is for refrigerants that have higher toxicity and have flame propagation at 140°F. These refrigerants have relatively low Lower Flammability Limits (LFL), high heat of combustion and the heat propagation velocity is not relatively low. Therefore, these refrigerants are classified as highly flammable and toxic.

The BHP / TR represents the power (Brake Horsepower) over capacity (TR) ratio of the compressor, the largest consumer of power in a refrigeration system. This ratio helps to evaluate the efficiency of the refrigeration system. Although not a perfect comparison, it will allow a user a window into relative efficiency of considered refrigerants. In this case, we have rated an open type screw compressor rated at the same operating conditions and then indexed the ratio off of ammonia as a refrigerant, which has the lowest BHP/TR ratios for all conditions. The indexed ratio represents the percentage of increased power consumed by that screw compressor with the considered refrigerant relative to the index.

The normal boiling point of a refrigerant is the temperature where, at atmospheric pressure, liquid refrigerant will evaporate or boil to a gas when additional heat is added. The pressure and temperature at which phase change occurs is a chemical characteristic unique to each refrigerant.

The compression ratio is the ratio of the higher (compressed) pressure divided by the lower (inlet) pressure of the compressor in absolute terms. This is a measurement of the amount of compression required and can reflect the work required and, thus, power consumed in compression. The higher the compression ratio, the more work is required to achieve that compression ratio and, likely, reflecting more power required to achieve the compression ratio. This can be one factor used to project expected performance when comparing refrigerants.

Today's refrigerants are used as either a pure compound refrigerant or a mixture (blend) of constituent, single compound refrigerants. An example of a refrigerant blend is R404A, which is made up of the constituent refrigerants R-143a, R-125, and R-134a. Each of the constituent refrigerants are single compound refrigerants.

Coefficient of Performance, or COP, is the unitless ratio of the energy output divided by the energy input. For a refrigeration compressor, the energy output is the measure of the refrigerating effect, and the input is the power input required to achieve the refrigerating effect. A high COP indicates a large refrigerating effect for the required energy input and, thus, an efficient refrigeration process. For lower COP, the converse is true and, thus, there is a relatively low refrigerating effect for the energy input and a relatively inefficient refrigeration process.

AR4 is the Fourth Assessment Report, published in 2007, providing the GWP values for the 100-year time horizon for different gases.

AR5 is the Fifth Assessment Report, published in 2014 and is the most current.

No, though it does introduce other considerations. The normal boiling point defines the temperature at which the refrigerant boils at atmospheric pressure. If a refrigerant is applied for use below its normal boiling point, the system will run in a vacuum. This can introduce several operational issues, including non-condensibles, moisture contamination, and refrigerant quality. Although refrigerarants can operate efficiently in a vacuum if properly designed and maintained, the operational concerns must be addressed.

The term “Drop in Replacement” can be misleading when referring to refrigerant replacements. In all cases, the replacement of a refrigerant will require some other work to be done to make the replacement refrigerant perform reasonably, but never the same as the original refrigerant. Extra work may include oil changes, seal changes, valve changes, equipment, etc. In no case should a replacement refrigerant be used to “top off” a system.

In the simplest terms, efficiency is defined as the work output divided by the work input. Expressing efficiency for an overall refrigeration system can be quite complicated, as it would require looking at the efficiency of every component at every stage of the refrigeration system. However, one contributor to relative efficiency includes the enthalpy difference of a refrigerant at different conditions. Enthalpy is generally expressed in the units of Btu/lb. This indicates how many lbs. mass of refrigerant is needed for a specific amount of heat to be moved. So, the higher the enthalpy number, the fewer the lbs. mass of refrigerant is needed. And in general, the less lbs. mass of refrigerant that needs to be moved within a system, the less energy that is needed to move it. So, higher-efficiency refrigerants may have higher enthalpy differences at operating conditions.

Enthalpy is from the Greek meaning "Heat Inside." It refers to the amount of heat released in a given timeframe, BTU/hr. Enthalpy represents the heat content of a refrigerant at a given condition and operating state. Evaluating the change in enthalpy allows designers to design appropriate refrigeration systems to meet their refrigerating needs.

Flammability is the ease with which a combustible substance can be ignited, causing fire or combustion or even an explosion. Regarding refrigerants, flammability is defined by a flammability rating set by ANSI/ASHRAE Standard 34. A refrigerant classification of "1" is a refrigerant that does not support combustion and is considered not flammable. All other refrigerant classifications, 2L, 2, and 3, all support combustion to some degree and are therefore considered flammable.

Fractionation is the change in mass composition of a refrigerant blend because one or more of the components is lost (for example through a leak) or removed. As the composition of the blended refrigerants changes, the performance of that blend changes. At some point the performance of the blend will change enough to affect the overall performance of the system. It should be noted that refrigerant blends which are designed to achieve the qualities of their contituent parts can have important characteristic changes as the blend concentrations change. For instance, if the lost refrigerant was included to lower the refrigerant flammability, the fractionalized refrigerant may have higher flammability characteristics than the installed refrigerant.

The Global Warming Potential (GWP) was developed to allow comparisons of the global warming impacts of different gases. Specifically, it measures how much energy the emissions of 1 ton of a gas will absorb over a given period, relative to the emissions of 1 ton of carbon dioxide (CO2). The larger the GWP, the more that a given gas warms the Earth compared to CO2 over that time period. The time period usually used for GWPs is 100 years. GWPs provide a common unit of measure, which allows analysts to add up emissions estimates of different gases (e.g., to compile a national GHG inventory), and allows policymakers to compare emissions reduction opportunities across sectors and gases.

Hydrochlorofluorocarbons (HCFC's) are a group of synthetic gases composed of hydrogen, chlorine, fluorine and carbon, primarily used for refrigeration. The HCFC's have shorter atmospheric lifetimes than CFC's. However, because they still contain chlorine they have been considered temporary replacements, though they are included as constituent components in many HFO/HFC blends. An example of an HCFC is R-22.

Hydrofluorocarbons (HFC's) are a group of synthetic gases composed of hydrogen, fluorine, and carbon, primarily used for refrigeration. Many HFC's are very powerful, short-lived climate pollutants that have been regulated out of use, although they are included as constituent components in many HFO/HFC blends. Typical examples are R-134a, and R-125.

Many refrigerants are comprised of blends of different refrigerants. The HFC/HFO blends utilize the lower GWP impact of HFO refrigerants and the low flammability ratings of HFC refrigerants. These refrigerants may have consequential glide characteristics. As with any blended refrigerant, the consequences of fractionation should be considered. HFC/HFO Blends are typically R-400 series blends along with HFC blends can all be found in the R-400 series. Review the composition of the refrigerant to understand the constituent chemicals.

Hydrofluoroolefins (HFO's) are unsaturated organic compounds composed of hydrogen fluorine and carbon and have been introduced as replacement refrigerants for more harmful gases. These are largely used in blends to reduce the flammability risk, while the HFO component reduces the GWP. Many of these chemicals have been categorized as PFAS chemicals having uncertain environmental and regulatory impacts. Examples of an HFO are R-1234yf and R-1234ze.

ANSI/ASHRAE 34 is an internationally accepted standard that assigns numbers to specific refrigerants based on their molecular makeup or if it's a blend of different refrigerants.

Glide, also called boiling point transition, is the difference between the starting and ending temperatur of the evaporating and condensing processes for a zeotropic refrigerant. Refrigerants with high glides present a challenge for heat exchanger performance and often require the system to operate less efficiently, at lower suction pressures and higher discharge pressures, when compared with azeotropic refrigerants having no glide. Compressors and heat exchangers must be carefully engineered to minimize these disadvantages.

Enthalpy difference through state change is a contributing component to the system efficiency equation, though it is only one of several. Enthalpy change by itself can be an indication of higher efficiency. However, the compressor style, the saturated suction and condensing temperatures, and the compression ratio will also play key roles in the equation.

The compression ratio is a contributing component to the system efficiency equation, though it is only one of several. Generally, the lower the compressor ratio, the less the input energy is required for compression, for a given refrigerant. However, the enthalpy differences should also be examined to obtain a more broader understanding of system efficiency.

The latent heat of vaporization, or enthalpy change (h_fg), of a refrigerant is a physical characteristic of that refrigerant measuring the amount of heat energy it absorbs per unit mass when it changes state from liquid to vapor. In essence, this is the refrigerating effect of the refrigerant at a given temperature and pressure. This refrigeration effect is another contributing component of the refrigerant efficiency that can be used to compare refrigerants.

The Lower Flammability Limit, or LFL, is the lower end of the concentration range of a flammable gas in which the gas will ignite in air at normal temperature and pressure. The LFL is generally expressed as a percentage by volume and defines the level below which the refrigerant will not ignite.

Natural refrigerants occur in nature’s biological and chemical cycles without human intervention. These materials include ammonia, carbon dioxide, natural hydrocarbons, water, and air.

The time-weighted average (TWA) concentration for a normal eight-hour workday and a 40-hour workweek to which nearly all workers can be repeatedly exposed without adverse effect, based on the OSHA PEL, ACGIH TLV-TWA, TERA OARS-WEEL, or consistent value.

ODP Stands for Ozone Depletion Potential. Some refrigerants (CFC's and HCFC's contain Chlorine which can deplete the Ozone Layer.

Per- and polyfluoroalkyl substances, known as PFAS, are widely used long-lasting chemicals, components that break down very slowly over time. Because of their widespread usage and persistence in the environment, PFAS chemicals can be found in water, air, fish, soil and even human blood, with some health impacts confirmed and others suspected. Many synthetic refrigerants have been classified as PFAS chemicals.

The Refrigerant Concentration Limit, or RCL, is defined by ASHRAE as the concentration limit (pounds of refrigerant per cubic feet) below which dangerous effects are avoided. These effects include oxygen deprivation, flammability, cardiac sensitivity, etc. Essentially, the RCL defines the lower limit of refrigerant concentration before dangerous effects occur.

When we talk about refrigerant emissions, we are generally talking about the release of refrigerants into the atmosphere. It is said that approximately 90 percent of refrigerant emissions happen at the end of the life of the equipment, a result of systems that are removed from service without proper reclamation of the refrigerant. It can be expected, therefore, that the remaining volume of emissions comes from unintentional leaks and other forms of intentional release.

Refrigerant Safety Classifications are defined and designated by ASHRAE Standard 15. The two or three-character alpha-numeric code communicates the flammability and toxicity of the refrigerants within each classification.

Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. As this relates to the refrigerant, toxicity is rated as either acute or chronic; acute toxicity is the adverse health effects from a single, short-term exposure, as might occur during an accidental release of refrigerant. Chronic toxicity is the adverse health effects oflong-term exposures. Toxicity is simply an indicator of how harmful a substance will be to an organism, depending on the type of exposure. The level of toxicity can quickly become very complicated. Refrigerants are classified as "lower toxicity", Group A, or "higher toxicity," Group B. These classifications are based on prescribed measures of chronic (long-term, repeated exposures) toxicity.

The U.S. EPA manages the SNAP program based on input from the industry. As new refrigerants are evaluated by ASHRAE, UL, AHRI, and other industry experts, SNAP releases them to the industry with certain restrictions, which may include the delisting ofsome refrigerants, the end use of the new refrigerant and the maximum charge per system.

SNAP stands for Significant New Alternatives Policy. The US EPA manages the SNAP program.

Refrigerant glide only applies to those blended refrigerants that are non-azeotropes (those in the 400 series). When a non-azeotrope enters the condenser coil, one of the refrigerants starts to condense first because each individual component has its own boiling point. As the refrigerant travels through the condenser, the remainder condenses. As this occurs the concentration of the saturated refrigerant changes. Hence, the refrigerant temperature at the start of the condensing cycle is higher than at the end. The difference in these temperatures is "glide". As the refrigerant enters the evaporator, the liquid of one of the refrigerants starts to evaporate before the rest, and again the temperature changes as the refrigerant changes from a liquid to a vapor. Each refrigerant in the blend has its saturation point (temperature where it changes from liquid to vapor or vapor to liquid as heat is added or removed) at a given pressure. Refrigerants that have glide can fractionate.

The theoretical COP is the highest theoretically achievable COP which assumes isentropic processes throughout the refrigeration cycle.  Although this ignores the inefficiencies that would be inherent within the devices and machines of the system, it provides an objective measure of the refrigerant's inherent properties and efficiencies.  It is calculated strictly by the enthalpies of the refrigerants at the specific states of the refrigeration cycle.

Please refer to www.iiar.org for additional information about refrigerants and refrigeration systems.

When ANSI/ASHRAE 34 assigns numbers to a new refrigerant, uppercase and lowercase trailing letters indicate different chemical compositions. Generally uppercase trailing letters are attached to blends and distinguish between the amount of one blend component vs. another refrigerant using the same components at a different mass ratio. Lowercase letters generally indicate whether the molecule has additional carbons attached to it. A full explanation is beyond the scope of this tool, but more information can be found in ASHRAE standard 34.

The SNAP Approval Dashboard on the Refrigerant Assessment Page pulls from the Notices (N) and Rules (R) released by the EPA. In each of these specific refrigerants may be allowed for a given application. In total, over 30 applications have been cited, though only the 14 most closely aligned with industrial refrigeration are displayed on this dashboard. The SNAP Notice or Rule reference is shown so that users can review the specific EPA Release as it is posted on the EPA.gov website where SNAP N-5 refers to SNAP Notice 5 and SNAP R-5 refers to SNAP Rule 5. With the most recent regulation to reduce the usage of high GWP refrigerants, many SNAP approved refrigerants will face a ban for given applications in 2025-2029. Refrigerants that are SNAP approved but do not face such High GWP limitations are shown in Green on the dashboard. Those that were previously approved but will face bans in all categories because they exceed 700 GWP are shown in yellow. For any application that the refrigerant has not had an identified rule or notice authorizing its use for that application, it will be in red with the word "NO" indicating that no identified rule or notice was found to authorize its use in that application.