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Frequently Asked Questions
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Refrigerant Blends
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2- Will a "perfect" drop-in be developed?
3- What is the difference between an azeotrope and a zeotrope?
4- When should I use an HFC and when should I use an HCFC?
5- Why do I need to remove the mineral oil when retrofitting from a CFC to an HFC?
6- Is R-134a a blend and how do I charge it?
7- I started charging a blend as vapor instead of liquid. Will my system work?
8- Are Forane® 409A, SUVA® 409A, and Genetron® 409A the same?
1- Why are there so many blends?
When the CFCs were eliminated, many refrigerant manufacturers developed their own replacements to satisfy the needs of the refrigeration and A/C industries. Each one of these blends is different from the others with regards to composition and performance characteristics. End users should educate themselves as to which blends are the safest, easiest, and most cost efficient refrigerants to use in their retrofits.
2- Will a "perfect" drop-in be developed?
Probably not. A perfect drop-in would be a refrigerant that replaced an existing product and showed no difference in performance or operation, and required no changes to the equipment. The refrigerants that are currently on the market are most likely the products that will be used to fulfill most end users’ retrofit needs.
3- Why do you need to charge blended refrigerants as liquids?
Refrigerant blends are simply a mixture of different refrigerant components. As such, if they are charged as vapor, the refrigerant with the highest vapor pressure will be charged at a higher proportion than the other component(s). Charging as a liquid is the only way to guarantee that the blend is charged within its designed composition.
4- What is the difference between an azeotrope and a zeotrope?
An azeotrope (500 series) is a refrigerant blend that cannot be separated through distillation at a specific temperature and pressure. These refrigerants do not have a measurable glide, and therefore fractionation is typically not a concern. Examples of azeotrope refrigerants include R-500, R-502, and R-507A. Zeotropes (400 series) are refrigerant blends that have a glide and can fractionate. Examples of zeotropes are Forane® 408A and Forane® 409A. Some zeotropes are referred to as near-azeotropes. These are 400 series refrigerant blends that typically have small or negligible glide and fractionation effects. Forane® 410A is an example of a near-azeotropic refrigerant.
5- When should I use an HFC and when should I use an HCFC?
HFCs should be used when installing new equipment. Most OEMs now manufacture new equipment containing HFCs. HCFCs should be used primarily for retrofitting existing CFC systems. Many HCFCs have good miscibility with mineral oil, and as such can often be used as CFC retrofits without having to change the oil. HCFCs typically make retrofitting much easier, and in some cases may improve system performance.
6- Why do I need to remove the mineral oil when retrofitting from a CFC to an HFC?
Mineral oil is not miscible with HFC refrigerants. As such, it may not be carried back once it has been swept out of the compressor. Once the mineral oil enters the system, it typically migrates to the coldest point in the system. This location is usually the end of the evaporator or just after the expansion device. Over time, this oil may decrease the heat transfer capability of the evaporator and could clog the expansion device.
7- Is R-134a a blend and how do I charge it?
No. R-134a is a single component (pure) refrigerant. To determine if a refrigerant is a blend, refer to the ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) designation (R #). Blends have 400 and 500 series R #s (R-410A, R-500, R-507A, R-502, R-404A). Any other ASHRAE designation denotes a single component refrigerant (R-12, R-22, R-23, R-123). Single component refrigerants can be charged in either phase, while blended refrigerants must be charged in liquid phase only. It is important to note that not all refrigerants have an ASHRAE designation, and many manufacturers use different numbering systems for their products.
8- I started charging a blend as vapor instead of liquid. Will my system work?
Fractionation of a refrigerant blend (separation of the blend components) can occur by removing the refrigerant from the cylinder as a vapor instead of a liquid. This can potentially lead to both safety and performance issues. As such, Arkema recommends charging all blends in liquid phase only. From a safety standpoint, a blend with an A1 (formerly A1/A1) ASHRAE safety rating (like Forane® 409A) will remain nonflammable, even after fractionation has occurred. Performance may be dramatically affected, depending on the extent of fractionation. If only a small amount of the refrigerant placed into the system was charged as vapor, the blend may perform adequately. The performance of systems containing larger percentages of a blend charged as vapor is more likely to be affected by fractionation. Typically, more of the high-pressure components will be found in the system, and less in the cylinder. Pressure checks on both the cylinder and the system may give an indication as to the extent of the fractionation. Measure the pressures of the cylinder and the system when they have reached a constant, uniform temperature. The system should be shutdown, and pressure measurements should be taken at a location where both liquid and vapor are present. If the pressures of both the cylinder and system are close to the value listed on the pressure-temperature chart, the extent of the fractionation effects are likely to be small. Significant pressure differences may indicate a high level of fractionation, which is likely to affect performance. Additionally, the refrigerant remaining in the cylinder may also be compromised. In these cases, we recommend contacting Arkema’s Refrigerant Hotline for technical support. It is also important to note that if the entire contents of a refrigerant blend container (full cylinder) are charged into a system as vapor, it will produce the same effect as charging the entire cylinder as liquid. Also, certain refrigerant blends (zeotropes) are more susceptible to fractionation than others. For example, fractionation is a greater concern when working with Forane® 409A (a zeotropic blend) than when working with Forane® 410A (a near-azeotropic blend) or Forane® 507A (an azeotrope).
9- Are Forane® 409A, SUVA® 409A, and Genetron® 409A the same?
Forane® 409A, SUVA® 409A, and Genetron® 409A are brand names used for the R-409A blends produced by Arkema, DuPont, and Honeywell respectively. The nominal blend compositions are the same, and each of the three major U.S. refrigerant manufacturers produces their blends to meet the ARI (Air-Conditioning and Refrigeration Institute) 700 standard for refrigerant purity. As such, each of these products should perform equally well in a system. They can also be used to top each other off in a system. Similarly, Forane® 134a, SUVA® 134a, and Genetron® 134a are also all R-134a. Arkema recommends using the ASHRAE designation (R #) to identify refrigerants.
(Forane® is a registered trademark of Arkema Inc.)
(SUVA® is a registered trademark of DuPont)
(Genetron® is registered trademark of Honeywell International)
Refrigerant OIls
10- When retrofitting, can I avoid changing to Alkylbenzene (AB) or Polyolester (POE) by using a lower viscosity mineral oil (MO)?
11- Will POE oil work with CFCs and HCFCs?
12- Can I use PAG oil instead of POE?
13- Can I add a small amount of hydrocarbon to my system to improve oil return?
14- How do I measure the contamination of the POE oil after doing an oil change?
10- When retrofitting, can I avoid changing to Alkylbenzene (AB) or Polyolester (POE) by using a lower viscosity mineral oil (MO)?
Reducing oil viscosity to promote oil return, when performing a refrigerant retrofit, is not a recommended practice. Although lowering the oil viscosity might improve its movement throughout the system, it also decreases the oil’s ability to properly lubricate the compressor. This could adversely affect the compressor life. Additionally, lowering the oil viscosity might increase the amount of free oil circulating throughout the system. Even a small increase in the amount of circulating oil can reduce system performance. The best way to ensure proper oil return when performing a retrofit is to use an approved, miscible refrigerant-oil combination. The new oil should have the same viscosity rating as the product it replaces.
11- Will POE oil work with CFCs and HCFCs?
Polyolester oils are typically miscible with CFC, HCFC, and HFC based refrigerants, and as such should promote proper oil return with any of these products. There are some known compatibility issues with POEs and elastomer materials used in older systems, so consult your OEM for specific refrigerant oil recommendations.
12- Can I use PAG oil instead of POE?
PAG (polyalkaline glycols) oils are used in automotive A/C applications, and are not typically recommended as substitutes for POE oils. Experience has shown that PAGs, used in systems with semi-hermetic / hermetic compressors, sometimes attack the motor winding insulation, causing shorting in the compressor. This is not a problem in automotive A/C, as these systems use open drive (belt driven) compressors that do not expose the motor windings to the refrigerant and oil.
13- Can I add a small amount of hydrocarbon to my system to improve oil return?
Although some refrigerant blends use small amounts of hydrocarbons in an attempt to promote oil return, “field-mixing” of refrigerants is an unacceptable practice. Controlling refrigerant flammability is an exacting science, and even a small amount of hydrocarbon can make refrigerant blends flammable. Hydrocarbons reduce oil viscosity. This also reduces the lubricating ability of the oil, which could potentially damage the compressor. Also, a small amount of hydrocarbon in a refrigerant blend does not ensure adequate oil return. Finally, hydrocarbons are highly flammable and as such require that strict safety precautions be in place before being used.
14- How do I measure the contamination of the POE oil after doing an oil change?
Oil test kits are available at most refrigerant wholesalers and distributors. These kits use a chemical reaction to measure the oil purity level. Refractometers are also available for this task. These electronic devices measure the scattering of light through the different oils to determine their relative concentrations.
