Transcription

Freon 407C and 410ARefrigerants (R-407C and R-410A)Properties, Uses,Storage, and Handling

Freon 407C and 410ARefrigerantsIntroductionThe compositions of Freon 407C and Freon 410A areas follows:BackgroundChlorodifluoromethane (R-22 or HCFC-22) has been usedas a refrigerant in various refrigeration, industrial cooling, airconditioning, and heating applications for over six decades.The low ozone depletion potential (ODP) of R-22 comparedto CFC-11 (chloro fluorocarbon 11) and CFC-12, as well asHFC-32HFC-125HFC-134aFreon 407C (R-407C), wt%232552Freon 410A (R-410A), wt%5050—Because Freon 407C and Freon 410A are mixtures ofits excellent refrigerant properties have helped facilitateHFCs, they have zero ODP.the transition away from chlorofluorocarbons (CFCs).However, R-22 will be phased out in the first quarter of theTable 1 lists the chemical names and formulae of the21st century. In preparation for this phaseout, Chemourscomponents that make up Freon 407C and Freon 410A.offers Freon 407C and Freon 410A, environmentallyacceptable alternatives to R-22.Freon 407C and Freon 410A Refrigerant DescriptionsFreon 407C is a non-ozone depleting blend of threehydrofluorocarbon (HFC) refrigerants. It exhibits performancecharacteristics similar to R-22. Freon 410A is a non-ozonedepleting blend of two HFC refrigerants. It exhibits higherpressures and refrigeration capacity than R-22.Table 1. Components of Freon 407C: HFC-32/HFC-125/HFC-134a and Freon 410A: HFC-32/HFC-125ComponentChemical NameFormulaCAS NumberMolecular ,2-TetrafluoroethaneCF3CH2F811-97-2102.02

Freon 407C and 410ARefrigerantsUsesTable 2 shows theoretical performance of Freon 407C,Freon 410A, and HCFC-22. Freon 407C exhibits similarFreon 407C refrigerant performs similarly to HCFC-22performance to HCFC-22, while Freon 410A givesunder evaporator temperatures ranging from –7 to 10 Csignificantly higher pressure and refrigeration capacity.(20 to 50 F). It is designed for use in new equipmentand as a service refrigerant for existing HCFC-22 airPhysical Propertiesconditioning, heat pump, and medium-temperaturerefrigeration equipment.General physical properties for Freon 407C andFreon 410A is intended for use in new air conditioningdiagrams for Freon 407C are shown in Figures 1 and 2.Freon 410A are shown in Table 3. The pressure-enthalpyapplications that have traditionally been serviced byAdditional physical property data may be found in otherHCFC-22. Many other applications are also pos sible, suchChemours publications. Thermodynamic propertiesas medium- and low-temperature refrigeration. Due to thebooklets are also available for Freon 407C and Freon 410Asignificantly higher pressures that Freon 410A exhibitsin both English and metric units. Piping guidelines are alsocompared to HCFC-22, a typical compressor designedavailable for Freon 410A.for HCFC-22 cannot be used with Freon 410A.Table 2. Theoretical Cycle PerformanceHCFC-22Freon 407C(R-407C)Freon 410A(R-410A)Refrigeration Capacity (HCFC-22 1.0)1.001.021.45Coefficient of Performance (HCFC-22 1.0)1.000.970.93Compression Ratio2.662.822.63Compressor Discharge Temperature, C76.771.274.1Compressor Discharge Pressure, kPa16611787262204.620.08Temperature Glide, KConditions: 43.3 C (110 F) condenser/7.2 C (45 F) evaporator/2.8 C (5 F) of subcooling/8.3 C (15 F) of superheat3

Freon 407C and 410ARefrigerantsTable 3. General Property Information: Freon 407C, Freon 410A, and HCFC-22PropertyMolecular WeightUnitFreon 407C(R-407C)Freon 410A(R-410A)HCFC-22g/mol86.2072.5886.47kPa abspsia1174.1170.291652.9239.731043.1151.40Boiling Point (1 atm) C ritical Temperature C F86.74188.1372.13161.8396.24205.24Critical PressurekPa al 3Density (Liquid) at 25 C (77 sity (Saturated Vapor) at 25 C (77 F)kg/m3lb/ft341.982.6265.924.1244.212.76Specific Heat, Liquid at 25 C (77 F)kJ/kg·KBtu/lb·( F)1.540.3671.840.4401.240.296Specific Heat, Liquid at 25 C (77 F) (1 atm)kJ/kg·KBtu/lb·( F)0.8300.1980.8320.1990.6850.157Vapor Pressure of Saturated Liquid at 25 C (77 F) , kPa (psig)kPa abspsia1173.4170.31652.9239.731043.1151.4Heat of Vaporization at Boiling KBtu/hr·ft·( F)W/m·KBtu/hr·ft·( 07720.08490.04580.010740.00621Viscosity at 25 C (77 F)LiquidVapor (1 atm)Pa·sPa·s1.60 x 10–41.23 x 10–51.20 x 10–41.27 x 10–51.59 x 10–41.30 x 10–5Flammability Limits in Air (1 atm)vol%NoneNoneNoneOzone Depletion Potential (ODP)(CFC-11, ODP 1)000.05Halocarbon Global Warming Potential (HGWP)(CFC-11, ODP 1)0.380.460.34CO2, GWP 1(100 yr ITH)160018901700IncludedYesYesYesppm (v/v) 8- and12-hr TWA100010001000Vapor Pressure at 25 C (77 F)Thermal Conductivity at 25 C (77 F)LiquidVapor (1 atm)Global Warming Potential (GWP)TSCA Inventory StatusWorkplace Environmental Exposure Level (WEEL)**Established by Occupational Alliance for Risk Science (OARS)4

Freon 407C and 410ARefrigerantsFigure 1. Pressure-Enthalpy Diagram for Freon 407C (ENG Units)5

Freon 407C and 410ARefrigerantsFigure 2. Pressure-Enthalpy Diagram for Freon 407C (SI Units)6

Freon 407C and 410ARefrigerantsFigure 3. Pressure-Enthalpy Diagram for Freon 410A (ENG Units)7

Freon 407C and 410ARefrigerantsFigure 4. Pressure-Enthalpy Diagram for Freon 410A (SI Units)8

Freon 407C and 410ARefrigerantsChemical/Thermal Stabilityclarity, or surface finish changes the rating to 1. Mixturesof CFC refrigerants and conventional mineral oils generallyStability with Metalsget a rating of 3, which is the limit of acceptability. The newStability tests for refrigerants with metals are typicallyrefrigerants and lubricants must outperform those beingperformed in the presence of refrigeration lubricants. Thisreplaced in order to be considered acceptable.test is run in sealed glass tubes at temperatures muchhigher than those encountered in refrigeration and airAfter the visual ratings were obtained, sample tubes wereconditioning systems and, therefore, referred to as anopened and the lubricant and refrigerant were analyzed.accelerated aging test. Results of sealed tube stabilityThe lubricant was typically checked for halide contenttests for HCFC-22/mineral oil and alkyl benzene lubricantsand breakdown products, while the refrigerant washave shown long-term stability in contact with copper,examined for the presence of decomposition products.steel, and aluminum. And, the fact that HCFC-22/mineralTable 4 summarizes the data from these sealed tubeoil and alkylbenzene systems have been performing in thestability tests for Freon 407C and Freon 410A andfield in air conditioning and refrigeration systems for thevarious commercial POE lubricants. Stability and visuallast 60 years verifies the results from these stability tests.ratings are listed for the neat refrigerant, the lubricant/Polyol ester lubricants (POEs) are for use with Freon 407Crefrigerant solution, and the three metals that were presentand Freon 410A. Therefore, stability tests of thesein the lubricant/refrigerant solutions. Samples were analyzedrefrigerants with POEs and metals were performed.for decomposition products in most cases. Typical levelmeasurements for decomposition products, if they areThe test method followed was generally the same asdetected, are in the low parts per million (ppm) range.ASHRAE 97 with several minor modifications. A 3-mLvolume of refrigerant/lubricant solution was heated in theThe results obtained from these sealed tube stability testspresence of copper, steel, and aluminum coupons in an ovenfor Freon 407C/POEs and Freon 410A/POEs indicatefor 14 days at 175 C (347 F) or 200 C (392 F) for 14acceptable chemical stability in the presence of commondays. Both the neat refrigerant and a mixture of lubricantmetals used in refrigeration and air conditioning systems.and refrigerant (50/50 volume ratio) were tested. Stabilityand visual ratings were obtained on both the liquid solutionsNote: Lubricant/refrigerant combinations shown throughoutand metal coupons after the designated exposure time. Thethis bulletin are for purposes of comparing and illustratingstability ratings range from 0 to 5, with 0 being the best andthe stability and compatibility of different lubricants with5 being the worst. Visual ratings indicate how the metal orFreon refrigerants. No recommendation is made orrefrigerant or lubricant/refrigerant solution appeared toimplied. Contact your original equipment manufacturera visual inspection. A rating of 0 indicates no perceptible(OEM) for the recommended lubricant for use withchange in appearance. Any perceptible change of color,Freon refrigerants.Table 4. Stability of Freon 407C and Freon 410A with Metals and Polyol Ester LubricantsFreon 407C withCastrol SW32Freon 407C withCastrol W22Freon 407C withLubrizol RL32Freon 410AMobil EAL22Freon with CPISolest ability Tests and Visual RatingsNeat refrigerantIron1T1T011Aluminum00000Fluoride ionND ( 7 ppm)ND ( 7 ppm)ND ( 7 ppm)ND ( 7 ppm)ND ( 7 ppm)Stability Ratings: 0–5 (Visual Ratings)0 Best1 First detectable change3 Equivalent to CFC/mineral oil(moderate discoloration or light corrosion)5 Coked (heavy solids or corrosion)NDPTGHNot determinedClear, brownTarnishGelHaze9

Freon 407C and 410ARefrigerantsThermal Decompositionpolymer. Polymers should always be tested under actualLike HCFC-22, Freon 407C and Freon 410A refrigerantsoperating conditions before reaching final conclusionsabout their suitability.will decompose when exposed to high temperatures orflame sources. Decomposition may produce toxic andThe ratings shown in Tables 5 and 6 are based on samplesirritating compounds, such as hydrogen fluoride. Theof each elastomer subjected to aging in a sealed tube in thedecomposition products released will irritate the nosepresence of the refrigerant and lubricant. For the neatand throat. Therefore, it is important to prevent exposurerefrigerant (both HCFC-22 and Freon refrigerant), theto decomposition products by following Chemours Safetyaging occurred for two weeks at room temperature. ForData Sheet (SDS) recommendations for handling.the Freon refrigerant/polyol ester lubricant mixture, agingoccurred for two weeks at 100 C (212 F). PhysicalCompatibility Concerns If HCFC-22 and Freon properties of the sample elastomers were measuredRefrigerants Are Mixedbefore and after aging.HCFC-22 and Freon refrigerants are chemicallycompatible with each other. This means they do NOT reactCompatibility with Plasticswith each other and form other compounds. However, whenCompatibility results are listed in Table 7 for R-22 neat,these refrigerants are mixed by accident or deliberately,Freon 407C neat, and Freon 407C/polyol ester lubricantthey will form mixtures that can be difficult to separate.mixture in the presence of plastics. Table 8 presents similarMixtures of HCFC-22 and Freon refrigerants cannot bedata for Freon 410A. It should be recognized that theseseparated in on-site recycle machines or an off-sitedata reflect compatibility in sealed tube tests, and thatreclaimer's typical facility. These mixtures will have to berefrigerant compatibility in real systems can be influenceddisposed of by incineration.by the actual operating conditions, nature of the polymersused, and compounding formulations of the polymers.Also, mixtures of HCFC-22 and Freon 407C or Freon 410APolymers should always be tested under actual operatingrefrigerants will have performance properties different thanconditions before reaching final conclusions about theireither refrigerant alone. Therefore, we do not recommendmixing HCFC-22 and Freon refrigerants in any system.suitability.Materials CompatibilityThe ratings shown in Tables 7 and 8 are based on samplesof each plastic subjected to aging in a sealed tube in theBecause Freon refrigerants will be used in many differentpresence of the refrigerant and lubricant. For the neatapplications, it is important to review materials ofrefrigerant (both HCFC-22 and Freon refrigerant), theconstruction for compatibility when designing newaging occurred for two weeks at room temperature. Forequipment, retrofitting existing equipment, or preparingthe Freon refrigerant/polyol ester lubricant mixture, agingstorage and handling facilities. The following compatibilityoccurred for two weeks at 100 C (212 F). Physicaldata is for Freon 407C and Freon 410A with someproperties of the sample plastics were measured beforeelastomers and plastics commonly found in air conditioningand after aging.and refrigeration systems.Refrigerant comes in contact with the motor windings inCompatibility with Elastomershermetic and semi-hermetic compressors. As a result, theCompatibility results are listed in Table 5 for HCFC-22 neat,motor materials must be compatible with the refrigerantFreon 407C neat, and Freon 407C/polyol ester lubricantand lubricant used in the system. Equipment manufacturersmixture in the presence of elastomers. Table 6 presentshave tested the compatibility of their motor materials withsimilar data for Freon 410A. It should be recognizedFreon refrigerants and polyol ester lubricants. Be surethat these data reflect compatibility in sealed tube tests,to check with the manufacturer of your equipment beforeand that refrigerant compatibility in real systems can beusing Freon refrigerant in any hermetic or semi-hermeticinfluenced by the actual operating conditions, nature of thecompressor.polymers used, compounding formulations of the polymers,and curing or vulcanization processes used to create the10

Freon 407C and 410ARefrigerantsTable 5. Compatibility of Freon 407C Refrigerant with Selected ElastomersR-22Freon 407C (R-407C)HardnessChange,UnitsRatingLinear Swell,%Freon 407C/Polyol EsterHardnessChange,UnitsRatingLinear Swell,%HardnessChange,UnitsRatingLinear Swell,%Alcryn0–3001400–10Buna S2a1–2101–1016–38Butyl lene lrez111—15–1616–23Natural iton A121–4214–12223–15Viton B218–17215–28218–32MaterialRatingComments0 Both % linear swell and hardness change are less than 10a Sample popped due to rapid degassing1 Either swell OR hardness change greater than 10b Sample distorted2 Both swell AND hardness change greater than 10c Significant loss of tensile properties11

Freon 407C and 410ARefrigerantsTable 6. Compatibility of Freon 410A Refrigerant with Selected ElastomersR-22Freon 410A (R-410A)HardnessChange,UnitsRatingLinear Swell,%Freon 410A/Polyol 0–305–6Buna S2a1–2110–14232–42Butyl 0–702–404–8EPDM0–1–801–3001Ethylene 1Kalrez111—15–1614–13Natural 12Viton A121–4212–15215–12Viton B218–17214–18219–32MaterialRatingComments0 Both % linear swell and hardness change are less than 10a Sample popped due to rapid degassing1 Either swell OR hardness change greater than 10b Sample distorted2 Both swell AND hardness change greater than 10c Significant loss of tensile properties12Linear Swell,%HardnessChange,UnitsLinear Swell,%

Freon 407C and 410ARefrigerantsTable 7. Compatibility of Freon 407C Refrigerant with Selected PlasticsR-22PlasticHigh-Density PolyethyleneFreon 407C (R-407C)Freon 407C/Polyol EsterRatingWeight Change,%RatingWeight Change,%RatingWeight 42c28Polyvinyl ied Polyphenylene Oxide2b331213Polycarbonate2b321214Poly(butylene 01Polyimide000100Polyphenylene Sulfide151213Polysulfone2130101RatingComments0 Best by visual inspection and weight changea No change1 Borderline by visual inspection and weight changeb Surface change2 Worst by visual inspection and weight changec Destroyed or dissolved13

Freon 407C and 410ARefrigerantsTable 8. Compatibility of Freon 410A Refrigerant with Selected PlasticsR-22PlasticHigh-Density PolyethyleneFreon 410A (R-410A)Freon 410A/Polyol EsterRatingWeight Change,%RatingWeight Change,%RatingWeight 172c26Polyvinyl fied Polyphenylene Oxide2b331314Polycarbonate2b321414Poly(butylene 01Polyimide000000Polyphenylene Sulfide151313Polysulfone2131212RatingComments0 Best by visual inspection and weight changea No change1 Borderline by visual inspection and weight changeb Surface change2 Worst by visual inspection and weight changec Destroyed or dissolved14

Freon 407C and 410ARefrigerantsCompatibility with Desiccantsevaporator and return to the compressor. This is why manyIn refrigeration systems, keeping the refrigerant andrefrigeration systems can operate properly, even though thelubricant and refrigerant are immiscible (yet partially soluble)lubricant free of moisture is very important. Dryers filledat evaporation temperatures. Other factors, such aswith moisture-absorbing desiccant are typically used torefrigerant vapor velocity and system geometry, play keyprevent moisture accumulation. The XH-6 desiccantroles in lubricant return. Overall, it is important to note thatproduced by UOP is typically used for R-22. While thislubricant/refrigerant miscibility is helpful, but notdesiccant, as well as UOP’s XH-9, is compatible withnecessarily essential, for proper system operation.Freon 407C and Freon 410A, both desiccants willabsorb R-32. The XH-11 desiccant from UOP is compatibleNote that HCFC-22/mineral oil and HCFC-22/alkylbenzenewith Freon 407C and Freon 410A and will excludeliquid phase miscibility are listed for reference. In general,R-32. Sporlan and Alco offer solid core driers that areHCFC-22 and mineral oil are miscible over most expectedcompatible with Freon 407C and Freon 410A.ranges of operating conditions for normal air conditioningand high to medium temperature operation. HCFC-22 andRefrigeration Lubricantsalkylbenzene are miscible over a much wider range ofMost compressors require a lubricant to protect internaltemperatures. Miscibility is generally believed to aidmoving parts. The compressor manufacturer usuallylubricant return to the compressor. Therefore, it mayrecommends the type of lubricant and proper viscositybe desirable when retrofitting an existing system ofthat should be used to ensure acceptable operationthis type to use a miscible lubricant with Freon HFCand equipment durability. Recommendations are basedrefrigerants. In general, Freon HFC refrigerants, such ason several criteria, which can include:Freon 407C and Freon 410A, are miscible with polyol Lubricityester lubricant and immiscible with alkylbenzene andmineral oil lubricant. Another important point is that Lubricant/refrigerant solubilityresidual mineral oil or alkylbenzene left in a refrigeration Lubricant/refrigerant miscibilitysystem after a retrofit to any HFC refrigerant decreases Compatibility with materials of constructionthe lubricant/refrigerant miscibility. This is one of thereasons why three oil changes are generally recommended Thermal stability and compatibility with other lubricantswhen a system is being converted or retrofitted to use HFCrefrigerants and POE lubricants.It is important to follow the manufacturer’s lubricantrecommendations for use with their equipment.Table 9 lists the liquid phase miscibility of Freon 407Cand Freon 410A refrigerants with multiple lubricants.Lubricant return to the compressors is very important asThe miscibility is determined by several factors: the relativewell. One factor that affects this is the liquid-phaseamounts of refrigerant and lubricant present, thelubricant/refrigerant miscibility, particularly at evaporatortemperature, the chemical makeup of the lubricant andtemperatures. Miscibility is the ability of two liquids to mixthe refrigerant, and the viscosity of the lubricant. The tableand form a single liquid phase—similar to water and alcohol.shows the temperature range over which several differentIdeally, the lubricant/refrigerant pair have sufficientcompositions of refrigerant and lubricants are fully miscible.miscibility or mutual solubility to allow the lubricant to flowwith the liquid refrigerant and return to the compressor.We strongly recommend that you review your systemEven if the lubricant/refrigerant pair are not miscible (twolubricant needs with the OEMs before any unit installationliquid phases form) in the evaporator, they may still haveor retrofit to Freon 407C or Freon 410A refrigerant.some degree of solubility. Solubility of refrigerant in lubricantlowers lubricant viscosity, which helps it flow through the15

Freon 407C and 410ARefrigerantsTable 9. Miscibility of Freon 407C and Freon 410A Refrigerants in Various Lubricants (Miscible Temperature RangeShown in C)Freon 407C (R-407C) in Various Lubricant Combinations Tested (% Refrigerant in Mixture)Mobil EAL32Lubrizol RL32Castrol 608090–6080–5080–558080–6080–5080No DataNo Freon 410A (R-410A) in Various LubricantsMobil EAL22CCMobil EAL68Castrol est 35Solest 7070–6070–50701070Safetyheadache, confusion, loss of coordination, and even lossUsers must have and understand the applicable Chemoursof consciousness. If you experience any of the above initialsymptoms, move to fresh air and seek medical attentionSafety Data Sheets (SDSs).as a precaution. Gross overexposure may be fatal.Inhalation ToxicityCardiac SensitizationFreon 407C and Freon 410A refrigerants pose no acuteAn effect that occurs with most hydrocarbons andor chronic hazard handled in accordance with Chemourshalocarbons at high concentrations is that the human heartrecommendations and exposures are maintained at or belowcan become sensitized to adrenalin (cardiac sensitization).recommended exposure limits, such as the ChemoursThis can lead to cardiac irregularities, such as irregularAcceptable Exposure Limit (AEL) of 1000 ppm. An AELpulse, palpitations, inadequate circulation, and even cardiacis an airborne exposure limit established by Chemoursarrest. The likelihood of these cardiac problems increasesthat specifies time-weighted average (TWA) airborneif you are under physical or emotional stress (due to theconcentrations, usually 8 hr, to which nearly all workers maypotential for increased amounts of adrenalin in yourbe repeatedly exposed without adverse effects. In practice,system). Freon 407C and Freon 410A refrigerants canshort-term exposures should not exceed three times thecause cardiac sensitization at inhalation levels well aboveestablished exposure limit formore than a total of 30 min during a workday.the recommended exposure limit, but the effect level variesThe exposure limits of 1000 ppm for Freon 407C andsymptoms of cardiac sensitization, move to fresh air andfrom person to person. If you experience any of the aboveseek medical attention as a precaution. Gross overexposureFreon 410A refrigerants are the same level as themay be fatal.Threshold Limit Value (TLV) established for HCFC-22.However, like HCFC-22, inhalation exposure above theAs part of treatment for cardiac sensitization, DO NOTrecommended exposure limit to the vapors of Freon 407Ctreat the patient with catecholamines, such as adrenaline,or Freon 410A refrigerants may cause human healthbecause these drugs could increase the risk of cardiaceffects that can include temporary nervous systemproblems.depression with anesthetic effects such as dizziness,16

Freon 407C and 410ARefrigerantsSkin and Eye Contactnot be allowed to exist with air above atmospheric pressureAlways wear protective clothing when there is a risk ofor at high temperatures; or in an oxygen-enrichedenvironment. For example: Freon 407C or Freon 410Aexposure to liquid Freon 407C or Freon 410A refrigerants.should NOT be mixed with air under pressure for leak testingIn liquid form, Freon 407C and Freon 410A refrigerantsor other purposes.can cause frostbite. When splashing of liquid refrigerant ispossible, always wear eye protection. If skin or eyes areRefrigerants should not be exposed to open flames orsplashed with liquid Freon 407C or Freon 410Aelectrical heating elements. High temperatures and flamesrefrigerant, flush area with lukewarm water (do not usecan cause the refrigerants to decompose, releasing toxichot water). If frostbite has occurred, call a physician. Ifand irritating fumes. In addition, a torch flame can becomeeyes are splashed, immediately flush with plenty of water fordramatically larger or change color if used in highat least 15 min. Call a physician.concentrations of many refrigerants; including R-500and R-22, as well as many alternative refrigerants. ThisSpills or Leaksflame enhancement can cause surprise or even injury.If a large release of vapor occurs, such as from a large spillAlways recover refrigerants, evacuate equipment, andor leak, the vapors may concentrate near the floor or in lowventilate work areas properly before using any open flame.spots and displace the oxygen available for breathing. Thiscould cause suffocation. When a large spill or leak occurs,Based on the above information, the following operatingalways wear appropriate respiratory and other personalpractices are recommended.protective equipment. Evacuate everyone from the areauntil it has been ventilated. Use blowers or fans to circulate Do Not Mix with Air for Leak Testingthe air at floor level. Do not re-enter the affected area unless– Equipment should never be leak tested with ayou are equipped with a self-contained breathing apparatus.pressurized mixture of Freon 407C or Freon 410Aand air. Pressurized mixtures of dry nitrogen andNonflammabilityFreon 407C or Freon 410A can be used for leak testing.Although HFC-32 is a mildly flammable compound, Bulk Delivery and StorageFreon 407C and Freon 410A refrigerants are– Tanks should normally be evacuated prior to initialformulated such that they remain nonflammable duringfilling and never filled while under positive air pressure.shipping, handling, storage, and use, as well as if leakageoccurs. Freon 407C and Freon 410A refrigerants– Tank pressure should never be allowed to exceed theare classified as A1/A1 refrigerants by ASHRAE. Also,maximum allowable working pressure when filling withFreon 407C and Freon 410A refrigerants have beenFreon 407C or Freon 410A. Relief devices onconfirmed as practically nonflammable (the same as R-22)either the tanks or supply system should be presentby Underwriters Laboratories, Inc. (USA), and both are onand in good operating condition.their list of recognized refrigerants.– Tank pressures should be monitored routinely.Combustibility of Freon 407C and Freon 410A– Air lines should never be connected to storage tanks.Freon 407C and Freon 410A are not flammable in Filling and Charging Operationsair at temperatures up to 100 C (212 F) at atmospheric– Before evacuating cylinders or refrigeration equipment,pressure. However, mixtures of Freon 407C or Freon 410Aany remaining refrigerant should be removed by awith high concentrations of air at elevated pressure and/orrecovery system.temperature can become combustible in the presence– Vacuum pump discharge lines should be free ofof an ignition source. Freon 407C and Freon 410Arestrictions that could increase discharge pressurescan also become combustible in an oxygen-enrichedand result in the formation of combustible mixtures.environment (oxygen concentrations greater than thatin air). Whether a mixture containing Freon 407C or– Cylinders or refrigeration equipment should beFreon 410A and air, or Freon 407C or Freon 410Aevacuated at the start of filling and never filled whilein an oxygen-enriched atmosphere, becomes combustibleunder positive air pressure.depends on the inter-relationship of 1) the temperature,– Filled cylinders should periodically be analyzed for air2) the pressure, and 3) the proportion of oxygen in themixture. In general, Freon 407C or Freon 410A should(nonabsorbable gas [NAG]).17

Freon 407C and 410ARefrigerants Refrigerant Recovery SystemsNonselective DetectorsEfficient recovery of refrigerant from equipment orNonselective detectors are those that will detect any typecontainers requires evacuation at the end of theof emission or vapor present, regardless of its chemicalrecovery cycle. Suction lines to a recovery compressorcomposition. These detectors are typically quite simpleshould be periodically checked for leaks to preventto use, very durable, inexpensive, and usually portable.compressing air into the recovery cylinder duringHowever, their inability to be calibrated, long-term drift,evacuation. In addition, the recovery cylinder pressureand lack of selectivity and sensitivity limit their use forshould be monitored and evacuation stopped in the

The compositions of Freon 407C and Freon 410A are as follows: HFC-32 HFC-125 HFC-134a Freon 407C (R-407C), wt% 23 25 52 Freon 410A (R-410A), wt% 50 50 — Because Freon 407C and Freon 410A are mixtures of HFCs, they have zero ODP. Table 1 lists the chemical names and formulae of the