A DROP-IN CFC-12 REPLACEMENT FOR AUTOMOTIVE AIRCONDITIONING by George H. Goble 286 W. Navajo W. Lafayette, IN 47906 ABSTRACT There currently exists a large number (millions) of automobiles with air conditioning systems designed to use CFC-12 as the refrigerant along with plans to produce such systems into the 1992-1995 time frame. During the 1992-1995 period, new production will transition to HFC-134a refrigerant based systems or other technologies which offer zero or little ozone depletion. CFC-12 based systems will finally cease production around 1995, but they will have a lifetime of about 10 years, extending the need for CFC-12, or a substitute until the year 2005 or so. This paper will present a ternary blend of refrigerants which may be able to be used as a transition refrigerant in CFC-12 designed automotive air conditioners until HFC-134a and other technologies are able to take over. Performance, oil miscibility, flammability, toxicity, and testing with a commercial dehydrant/leak sealant will be discussed. INTRODUCTION A ternary blend of HCFC-22, HCFC-142b (chlorodifluoroethane), and small amount of R-600a (isobutane) has been found to provide acceptable operation on several automobile airconditioning systems designed for use with CFC-12. Some capacity increase has been noted in most systems, probably from the blend being non-azeotropic, leading to better utilization of the condenser and evaporator . This blend features 95% less ozone depletion potential (ODP) than does CFC-12 (ODP of 0.05 vs CFC-12 with ODP 1.0). This blend is 55% HCFC-22, 37% HCFC-142b, and 8% isobutane by weight and is compatible with mineral oils currently used in CFC-12 systems. Testing began in August 1990 in two vehicles, a 1990 Pontiac Transsport, and a 1978 Datsun 810. A 1979 Grand Prix was added in October 1990. By July 1992, some 500 vehicles were running this blend. Only one failure has occurred. A 1984 Buick Century had a DA-6 compressor fail. The tear down of the compressor revealed the thin Teflon piston rings had broken, and fragments had lodged in the valves, holding them open. Local mechanics state this is an extremely common failure mode for this compressor (with R-12), and one mechanic reported he changed 38 DA-6 compressors in a two month period during the summer of 1991 which had failed for the same reasons. The remaining intact Teflon piston rings, did not appear to be swollen or affected by this blend. Currently, there is no reason to suspect this blend as being the cause of this failure. The first two vehicles were instrumented with gauge manifolds (all copper lines) in the passenger compartment along with thermocouple probes, so temperatures and pressures could be monitored in real life driving situations. The 1990 Transsport, ran the standard CFC-12 charge for the first year of its life, it then was charged with the ternary blend. After 8 months no loss of charge was noted from performance and pressures. Refrigerant has remained clear and dry as observed in an installed liquid line sight glass. PERFORMANCE Testing of this blend has shown significant (around 4F-13F) decrease in discharge air temperatures at ambient temperatures over 80F over that of what CFC-12 did. Condensation and evaporation of the refrigerant appear to occur over a larger band or "glide", thus achieving better utilization of the evaporator and condenser. At lower ambients, the capacity (cooling) of this blend drops off to approximately that of CFC-12, mostly from the reduction in head pressure. Different systems perform differently. CCOT (orifice) systems generally show more increase in capacity than do expansion valve systems. Compressor discharge temperatures did run slightly higher than with R-12. Hot ambients (90-100F) days produced discharge temperatures in the 180F range. The same systems had R-12 discharge temperatures in the 160F range (average city driving). Even though slightly higher, the compressor discharge line temperatures are still low enough to prevent refrigerant/oil breakdown. OIL MISCIBILITY In addition to refrigeration effect, the isobutane makes this blend miscible in standard mineral oils used in CFC-12 systems. Neither HCFC-22 nor HCFC-142b by itself are very miscible with mineral oils used in CFC-12 systems at evaporator temperatures (32F). The "Upflow" evaporators and large diameter suction lines commonly found in R-12 systems may cause problems with oil return to the compressor, resulting in compressor failure, when the refrigerant is not miscible in the oil being used . This blend stayed dissolved in oil (20% oil) by volume, at 32F (approximate evaporation temperature in auto A/C systems) with Suniso 5GS (525 SUS viscosity) mineral oil of the type used in auto A/C systems. Suniso 3GS (150 SUS viscosity) mineral oil (naphthanic) and Virginia KMP 150 viscosity mineral oil (paraffinic) also stayed dissolved in refrigerant at 32F. Both 150 viscosity oils were completely dissolved at 0F. Around 10% (by volume) of Suniso 525 SUS viscosity oil dissolved in the refrigerant at 0F. This 525 viscosity oil is normally used in auto A/C systems which only operate at 32F or higher. Typically, around 10% by volume, oil is circulated with the refrigerant in auto A/C systems. FLAMMABILITY The current blend could not be ignited, even after a 4 month leak down test (over 1/2 the charge had been lost). It should be noted that even CFC-12 can be "flammable", when it contains dissolved oil, and a rapid release occurs. The oil atomizes into a fine mist and can be ignited. It has been reported that HCFC-22/HCFC-142b mixtures are nonflammable up to concentrations of 68% weight of HCFC-142b . Many "nonflammable" refrigerants, which contain hydrogen atoms, can become flammable if mixed with large amounts of air under pressure. Such examples include HCFC-22 and HFC-134a. For this reason, this blend and other refrigerants and blends containing hydrogen atoms should not be diluted with air, and pressurized (such as for leak testing). Diluting the refrigerant with dry nitrogen is ok. Being a non-azeotrope, this blend will change composition during the leaking process. Recharging (topping off), systems with partial charges is prohibited. The entire charge must first be removed, and a recharge done with new (non recycled) material. Repeated topping off of leaking systems could lead to this blend becoming flammable, thus the requirement of always doing a full recharge with new material. This requirement should not impact automotive air conditioning severely. This difficulty rapidly becomes prohibitive in large commercial systems, where topping off leaking systems is the normal mode of operation. Non-azeotropic blends will be cumbersome in anything except automotive and small systems due to the requirement that the whole charge be removed. Reconstitution of leaking non-azeotropic blends to known composition is beyond the scope of almost all service technicians. TOXICITY Unlike the new generation of "hyperfluorinated" refrigerants, all of the ingredients of this blend have existed for decades and their properties are well known. HCFC-142b is commercially available in large quantities. LEAKING AND LEAK SEALING IN CARS It has been observed, that a large percentage of older (4 years or older) cars, seem to have continual slow refrigerant leaking problems. Even when the leaks are identified and repaired, many are low on charge by the following summer. New leaks form, and/or hose diffusion may be occurring and may be undetectable due to the large surface areas or difficult to access areas. Airconditioning service shops, often can only repair "obvious" leaks or change "bad" components. Some leaks have been observed to be temperature sensitive (e.g. only leaks in the winter when parts contract) Many cars are continually recharged at 2 month to 1 year intervals, since the leaks are impossible to find/repair. Many owners of older cars are not willing to pay the cost of an entire new system being installed (often over $1000), just because the leaks cannot be found and repaired. State laws are being enacted (such as Florida, 7/1/91), which prohibit automobiles from leaving a service shop unless the leak is repaired. If the leak is not repaired, then the CFC-12 must be removed from the system before releasing the car to the owner. Mechanics have reported to the author that they have encountered certain brands of connectors which always leak small amounts of charge, even if they are new and this has led to much frustration as they cannot be properly "fixed". A commercial dehydrant/sealant, "DRY-PAK" and "CRYO-SILANE" made by Cryo-Chem International , have been tested with this blend at higher dilutions than their normal product. System drying and sealing of leaks has been observed to be satisfactory for the three week to 1 year "leak rates". This also stopped diffusion through hoses and helped prevent composition changes in the blend due to leaking. Elimination of constant recharging reduces the "effective" (per car) ODP further. If a car "saves" five additional recharges in its lifetime, then the effective ODP becomes 0.01 for a 99% reduction in ozone depletion from CFC-12. The sealant cost per car works out to be less than $20. Shaft seal leaks are not repaired, but they are reduced. Use of this sealant requires the system be "dry", with no significant moisture trapped in the drier. The sealant manufacturer requires that the drier be changed prior to use. Experience has found this to be true. Using this blend [with sealant] on "wet" systems (without changing the drier), resulted in the sealant being neutralized and no sealing action. No harm was caused be this action other than sealant being wasted. The systems continued to perform (and leak) normally. Changing the drier and orifice are always good refrigeration practices. Old driers can have their desiccant bags break, clogging the system with clay from the desiccant binder. PROCEDURES Being a non-azeotropic blend, certain procedures must be followed to prevent composition changes. The most obvious is that the system must be "liquid charged", carefully to avoid slugging the compressor. Systems with partially leaked charges, should be discharged before recharging, to achieve a known composition. This problem is greatly reduced by the addition of the above sealant. Under the "1990 Clean Air Act", this blend cannot be vented to the environment after certain dates (mostly in 1992), depending on the type of service (mobile airconditioning, fixed, size of service shop, etc). It can be "recovered" (pumped into a tank) with CFC-12 recovery equipment and returned to the manufacturer to be reclaimed to new standards or be destroyed, it cannot be reused on site. CONCLUSIONS The author believes this blend can be used to keep existing and future CFC-12 automotive airconditioning systems running until they reach their normal end of life. This blend may take some pressure off the race to get HFC-134a, its complex lubricants and field procedures operational, for retrofitting existing CFC-12 systems which fail in the field. Being a blend, "custom" refrigerants can be made for extra performance in hot humid climates with minor system modifications (a high pressure cutout switch). Testing is currently ongoing in this area. It is possible to deliver subfreezing air continuously at ambients of 100F (highway driving). Patent pending. REFERENCES  Kruse, H. "The advantages of non-azeotropic refrigerant mixtures for heat pump applications" Int. J. Refrig. 1981 vol 4 May pp 119-125  ASHRAE, 1984 Systems Handbook, pp 29.11  Kuijpers, L., Miner, S., "The CFC issue and the CFC forum at the 1988 Purdue IIR conference", Int. J. Refrig. 1989 vol 12 May pp. 123  Private communication with Packo, J., Cryo-Chem Intl. Inc.
From: firstname.lastname@example.org (George Goble) Newsgroups: rec.autos.tech,talk.environment Subject: Re: R-406A (aka "GHG-12") flammability (Was: Re: A/C converson from Freon to R134- Necessary?) Date: 6 Nov 1994 01:35:51 GMT Organization: Purdue University Engineering Computer Network Lines: 83 In article <email@example.com> firstname.lastname@example.org writes: >In article <1994Nov3.email@example.com>, firstname.lastname@example.org (Gregory P Dubois-Felsmann) writes: >|> As George Goble has pointed out, the refrigerant blend he has invented, >|> "GHG Refrigerant-12 Substitute", designated R-406A by ASHRAE, has been >|> designated as an acceptable substitute for R-12 in a variety of >|> applications by USEPA -- but not for use in mobile A/C. >|> >|> Discussion on the net has mostly focused on the question of flammability. >|> I thought readers might be interested to see what EPA itself has said with >|> regard to R-406A. >|> >|> This is taken from the Federal Register of 26 August 1994, in a "notice >|> of acceptability" under EPA's Significant New Alternatives Policy program: >|> >|> > (a) R-406A.--R-406A, which consists of HCFC-22, HCFC-142b, and >|> > isobutane, is acceptable as a substitute for R-500 in retrofitted >|> > centrifugal chillers. Because HCFC-22 and HCFC-142b contribute to ozone >|> > depletion, this blend is considered a transitional alternative. >|> > Regulations regarding recycling and reclamation issued under section >|> > 608 of the Clean Air Act apply this blend. HCFC-142b has one of the >|> > highest ODPs among the HCFCs. The GWPs of HCFC-22 and HCFC-142b are >|> > somewhat high. Although HCFC-142b is flammable, the blend is not. After >|> > significant leakage, however, this blend may become weakly flammable. >|> >|> The notice goes on to declare R-406A an acceptable substitute in a >|> long list of applications. I can post the list (or ghg can, since >|> it's his stuff :) ) if there is interest... >|> >|> I'd be curious to hear if George Goble himself has something to add >|> to this. The list is pretty much everything (for R-12/R-500 retrofit) except for MVAC (cars and mobile A/C which cools people..).. OK for Mobile refrigerated cargo though.. (that counts as stationary) --ghg >|> >|> I'll post something later about EPA's current thinking about mobile A/C. >|> >|> Btw, this sort of discussion would probably be welcome in the >|> "environmental tech" group we keep discussing creating someday. >|> >|> -- >|> Gregory > > My guess here is the keyword that R142b has one of the highest > ODPs among HCFCs. ODP is Ozone Depletion Potential. So the > components of R406A are primarily HCFCs and isobutane. Granted > HFCFs as a group have less ODP than CFCs(like R12) but maybe the > EPA didn't want something with ODP at all in cars which comprise > a lot of refrigerant. > >Greg Marciniak R-406A is (by wt) 55% HCFC-22 41% HCFC-142b and 4% R-600a (isobutane) ODP of HCFC-22 is .055 ODP of HCFC-142b is .065 ODP of R-600a is 0.0 This gives ODP of R-406A as .0569 ODP of R-12 is 1.000 As a group the HCFCs are all grouped in a bunch at ODPs of .03-.06 which is a twentyfold reduction of ODP compared to R-12. Currently EPA class II substances (HCFCs) are permitted in some forms all the way out to around 2030..Various phaseouts and other stipulations are placed on HCFCs (like ok for service but not new mfgr, etc) at earlier dates (around 2010 or so?) and are different in different countries.. This area is in constant flux. ODP is not the reason for R-406A not being on the automotive list. R-406A (GHG R-12 substititute at the time) was withdrawn (by the mfgr) from the EPA automotive SNAP MVAC section over a year ago, due to the "bad" political climate in the automotive industry towards blends. For EPA Approval, it appears that the "industry involved" has to "request" the EPA to approve it.. With the exception of the "slip up" on FRIGC, how many auto companies are going to request EPA approval to get blends in? All the auto companies (and MACS) spend large sums of money to eliminate anything but -134a. R-406A was "requested" by some members of the stationary refrigeration industry.. The stationary industry is not like "fighting with a bunch of mean junkyard dogs" like the auto industry was. --ghg
From: email@example.com (George Goble) Newsgroups: rec.autos.tech Subject: Re: HC-12a replacement for R-12 Message-ID: <firstname.lastname@example.org> Date: 26 May 1995 12:51:31 GMT Organization: Purdue University Engineering Computer Network In article <email@example.com> firstname.lastname@example.org (Rob Lockhart) writes: >I could be....Elvis? (email@example.com) wrote: > >: GHG-12 contains 8% isobutane by weight. It is present in order to >: disolve the mineral oils present in A/C systems. GHG-12 has been >: shown to be non-flammable. It should be noted that R-134a (the new >: stuff) is flammable when mixed with air and under pressure. It >: should also be noted (again) that R-12 is flammable when vented thru >: a small hole and the mineral oil is atomized. Just because MACS and >: various government agencies don't like the alternatives doesn't mean >: there is anything wrong with them. > >: --steve > >Steve, > What is GHG-12? Something new? Please tell us more information >about it, or some point-of-contact for this information. I only have >info about HC-12a from OZ Technology. > >--- > Rob Lockhart firstname.lastname@example.org > Virginia Tech Physics Department "GHG-12" is not a legal name, but people keep calling it that. "Anything-12" is a brand of R-12 by ASHRAE nomenclature definiation. For "Anything", insert "Freon" (Dupont), "Genetron" (Allied Signal), "Isotron" (Pennwalt now Atochem), Solkane (Solvay), etc, etc, etc. All are registered trademarks of the company following in ()'s. Like "Xerox", many people call R-12 (dichlorodifluoromethane), "Freon". There are many different kinds of "Freon", but R-12 is the most common. You are not supposed to call it "Freon" if it was not made by Dupont. The real name for "GHG-12" is "GHG Refrigerant-12 Substitute", or more recently listed by ASHRAE as R-406A. R-406A was invented in August 1990 by me, more or less as something "neat" to do. It is currently mfgr by "People's Welding Supply" in W. Lafayette, IN. R-406A is composed of 55/41/4 weight percentages of R-22/R-142b/R-600a. R-600a is isobutane and it is used to give the refrigerant oil miscibility with R-12 mineral oils.. The refrigerant has to be miscible in the oil used, so the oil returns from the evaporator to the compressor correctly. This is the crux of the problem with R-134a and why special complex (and sometimes unstable) oils had to be developed. R-134a does not dissolve in R-12 mineral oil. Early developmental blends of GHG R-12 Substitute used 8% isobutane, but it was discovered that 4% also worked fine and it has been 4% ever since 1991. R-406A is covered under US patents 5,151,207 and 5,214,929. Originally GHG R-12 substitute was developed for cars. It was originally in around 2000+ cars back in 1991-1992, and it worked fine. Foreign vehicles or port-of-entry A/C addon systems typically used "nitrile" hoses, and the charge leaked out after a summer or so. Almost all US built cars already used "barrier" hoses for many years -- These work fine with no significant leakage. R-12 leaks much faster thru nitrile also. With the exception of changing nitrile hoses to barrier hoses, no system changes were needed. Cooling was 20-40% better than R-12 in many cases, due to the "glide" in the blend making better use of the condenser for heat rejection. R-406A is nonflammable as shipped. If it has undergone extensive vapor leakage, it can become "weakly flammable", but still has no "flash point". It the weakly flammable state, a beaker of it can be ignited with a propane torch, but it self extinguishes due to combustion byproducts (similar to how Halon works), gas or liquid streams venting from cylinders (worst cast composition) cannot be ignited with a propane torch. Compared to propane/butane/etc, R-406A is only about 1/100 or less active in it's worst case conditions. There are Safety testing papers (prepared by Safety Consulting Engineers) and video tapes available showing all this. The end of the tape shows 8oz of propane being "spilled" as a comparison..and the propane made quite a fireball. It graphically shows the difference between R-406A in worst case and hydrocarbon (propane/butane) based refrigerants in ignition scenarios. Call Monroe Air Tech , 800-424-3836 for the video or other info on R-406A. The auto industry together with MACS (Mobile Air Conditioning Society) does not want any substitutes for old cars. They have fought tooth and nail to get everything "banned" except R-134a. They have virtual control over most TV shows Magazines, papers with the power of their advertizing. Anyone says something "bad" about R-134a retrofits, or anything "good" about any other substitute, all the car makers simply jerk all their ADs, causing financial ruin or hardship to the publication involved. R-134a has numerous problems when trying to use it to "retrofit" older R-12 systems to it. 1) PAG oils used in the retrofit may be destroyed by aluminum chloride (from pre-existing R-12) already in the system piping. These chlorides are impossible to flush out. 2) If Ester oils are used instead, they have lower lubricity than PAG oils, but they are 10X more moisture sensitive than R-12 mineral oils, and contamination can cause the Ester oils to break down into fatty acids and alcohols (their original components of formation). PAG oils are around 100X more sensitive to moisture than R-12 mineral oil. DUring system service, when it is left open, moisture can get in, causing failures a few months later (after the 90 warranty is over) 3) R-134a has a lower "critical" temp. Critical temp of a gas is the temp which at or above it cannot be liqufied, at any pressure. R-134a crit is 214F or so, R-12 is around 233F. Condensor temps (due to the hot radiator being there) can easily hit 212F or more during "hot idle" (gridlock).. R-134a ceases to work (plus has very high pressures over 450 PSIG) under these temps. 4) R-134a has lower capacity (in an R-12 system), than R-12 or other substitutes. R-134a has a boiling point of -15F vs -21F for R-12. 5) R-134a can be made to have good performance, but this requires design changes, notably a MUCH larger condenser, higher airflow, etc (easier to do in a NEW CAR) Consider this, if you get an R-12 car retrofitted to R-134a and you may get poor performance, plus in a few months, your PAG oil may break down and "gumm up" the whole system, your only choice (no R-134a Flush approved) would probably be to replace everything at $1500-$2000. Due to the chloride contamination problem, the "only correct" R-134a retrofit is to change anything which has touched R-12. (How convient that R-134a and PAG oil works fine in "new" systems) How many are gonna fork over $1500-$2000 for a new A/C system in an old car? You are gonna "trade in" to get a "new" car. Around 140,000,000 R-12 cars in the US. Assume around 1/3 (50,000,000) trade for a new car..($10,000 est).. so that is 50,000,000 X $10,000 or $1/2 trillion in extra new car sales above and beyond normal. Now you know why MACS and the auto industry have to do anything they can to stop substitues. Go figure. There is a Gov't (DOE) risk assesment (done by Arthur D. Little) on using propane, etc (flammable hydrocarbon) refrigerants in cars.. It found the risk increase was essentially NIL, with no impact to insurance rates either. OZ-12 and (HC-12a?) were in around 50,000 things a year or so ago, and I heard of no reports of fire or explosion, except "rigged" tests and demos to incite fear in the public. Only 1.5lbs of hydrocarbons are used in a car A/C.. You have over 100lbs of gasoline onboard also.. The DOE assessment, in worst case secarnios, such as the total hydrocarbon charge release in the passenger cmpt (very very unlikely), and the ingition/explosion of it, resulted in minimal or no injuries (maybe singed hair). Windows blow out at 3Psi overpressure (preventing eardrum damage) and the "thermal pulse" is too short to be significant. MACS has been passing out photos/articles of an A/C system which "exploded", showing a "puffed up" accumulator, which had a hole burned in it (overpressure from the inside). MACS claimed a refrigerant which had 5% butane was used, implying it was the "cause". (this refrigerant is assumed to be FRIGC, since it mostly closely matches what was given). FRIGC is mostly R-134a. R-134a and most other HFC/HCFC refrigerants are flammable (incl R-22, R-406A, etc) when mixed with large quanities of air UNDER PRESSURE. This incident was most likely not caused by the "5%" isobutane, but the bulk of the charge, R-134a burning in a system which was not properly evacuated or somehow became filled with a large amount of air. Even if the system was filled with a pure hydrocarbon (propane/butane, etc), and ignited, hotwire burns into aluminum line, etc, the resulting fire would be EXTERNAL to the A/C system.. No fire would happen "inside" the A/C (it takes lots of air in there) to cause internal ignition, puffed up acculumators, etc.. Before blaming the refrigerant, MACS should do a credible scientific investigation and release those reports instead. Where are all the credible investigation reports of the "numerous" explosions (in real life, not rigged tests) of cars blowing up with hydrocarbon refrigerants?? Why doesn't someone publish them? Why dont they also publish the reports of R-134a cars "exploding on impact" (Front end blown off Police car in minor front end collision?) Could that be air mixed in with R-134a in improperly charged system? Hydrocarbons work very well as refrigerants (I made one in 1989/1990 and it worked fine, but dropped it due to public fear). I see the only real problem with hydrocarbons is that they are "commodity" items, and a "A/C recharge" costs only $.50 or so in materials.. Where as one can get $300 or a R-134a recharge or better yet a "new car sale" when one is not needed!. All refrigerants use "oil" of one sort or another, about 8-12 fluid oz range in the system. No matter what the refrigerant, (even R-12), this oil can be very flammable or explosive, if brought out in a rupture (in a mist or fog)..1.5oz of R-12/oil generated a 10ft fireball in a lab test. See my homepage for an R-12/oil fire, venting (in 1991 when it was legal) 3lb of R-12/oil and it sustained ignition. Oil can get sprayed on hot exhaust manifolds or cat converters in a wreck. Due to this extremely bad "political" climate in the auto industry, R-406A was withdrawn from EPA SNAP consideration for Automotive a couple of years back. The auto industry has more or less left us alone ever since. R-406A is EPA SNAP approved for most everything else (except automotive and mobile A/C) in the US. Hope this helps. --ghg (Inventor of GHG R-12 Substitute, R-406A) http://ghg.ecn.purdue.edu
From: email@example.com (George Goble) Newsgroups: rec.autos.tech Subject: Re: Celebrate! AC retrofit debate now IRRELEVANT! Message-ID: <firstname.lastname@example.org> Date: 27 Jun 1995 01:14:03 GMT Organization: Purdue University Engineering Computer Network Lines: 27 In article <DAspM6.L43@ntmtv.com> Spud <email@example.com> writes: >I have a question about the availability of the new schraeder valves. > >I have a '79 Chrysler that i hope to have the a/c working again. I like >the R406a idea. Are the new schraeders for R406a identical to those for >R134a? No.. yet another unique thread type (+ adaptors to convert to back to R-12 fittings), thank MACS and the auto industry for this hassle. >How easy are the to get? not yet.. first production run expected in a week or two (seven types total).. >I'll need to replace all of the hoses and seals. I presume. The a/c >system has been out of order for 3 or 4 years now. If the hoses are nitrile, they should be changed, a car this old will almost certainly have "rotten" hoses.. Change the drier also. This holds for R-12 also. The desiccant bag in the old drier may bust, clogging the system with "clay" type powder.. --ghg
From: firstname.lastname@example.org (George Goble) Newsgroups: rec.autos.tech Subject: Jeff Levy's @ US EPA response to ghg's last R-406A posting Message-ID: <email@example.com> Date: 22 Jul 1995 13:30:43 GMT Organization: Purdue University Lines: 129 [ long email header snipped out ] [ Jeff Levy @ US EPA called me yesterday, they are apparently having problems posting news (long reply?) at the moment. I agreed to post his reply. Email responses on this article [meant for the poster] should be directed to "firstname.lastname@example.org" --ghg] -------------------------------------------------------------------------- George - I posted this, but if it doesn't reach you, please repost it for me. >From: email@example.com (Jeffrey Levy) >Newsgroups: rec.autos.tech >Subject: R-406A, EPA, and flammability >Organization: USEPA >X-Newsreader: WinVN 0.92.6 Before I begin explaining, I need to make one point: everything I say in rec.autos.tech, and everything anyone says on the phone, is still not legally binding the way a published rule is. That said, let me first state that George Goble has posted several posts that were correct at the time, and that the manufacturer of R-406A has not, to date, done anything that I am aware of that violated any EPA rules. The situation of auto AC is a complicated one. I know people can be confused by EPA rules, and I know there are a lot of questions about the thought processes behind them. I'd like to give a decent try at explaining what's up.George's recent post about the general process of SNAP submission and the legality of sale was accurate, *in general*. When a substitute is submitted, it becomes legal for sale 90 days later, even in the absence of a final EPA decision. It's not EPA-approved, but it is legal. Many people assume that if it's on the market, it's EPA-approved. That is the case when a new drug appears - it can't be marketed until the FDA approves it. But when the U.S. Congress wrote the Clean Air Act in 1990, that's *not* the authority they gave EPA. The law says: "The Administrator shall require any person who produces a chemical substitute for a class I substance to provide the Administrator with any such person's unpublished health and safety studies on such substitute and require producers to notify the Administrator not less than 90 days before new or existing chemicals are introduced into interstate commerce for significant new uses as substitutes for a class I substance." (FYI, CFC-12 is a class I substance) Note that nowhere does it prohibit sale until EPA makes a final determination. So that's the root of the confusion between "legal for sale" and "EPA approved." Becoming legal for sale is just the default in the absence of an EPA decision, rather than being a positive statement by EPA. George's post on this point was pretty clear. If nothing had ever been said about automotive refrigerants, then R-406A would be legal for sale, but not EPA-approved, in September. We never made any determination that R-406A would be legal for sale. That's a situation that derives from the Clean Air Act itself. My posts were simply an explanation of that situation. The next thing to know is how we make final rulings. If we find that a substitute is acceptable, we simply publish the information in the Federal Register without any need for public comment. That was the case for the use of R-406A as a refrigerant in many stationary uses, like refrigerators and ice machines. However, we are putting certain use conditions on all automotive refrigerants. That means we must first propose the conditions, take public comment, and then write a final rule. That process can take as long as a year, unfortunately, although we're trying to shorten it. One reason for the length of time is that the Office of Management and Budget is entitled to a 90-day review of both the proposal and the final rule, so there's at least an allowed six month additional review beyond EPA's analysis. Several Presidents, going back at least as far as Reagan, have issued Executive Orders on OMB review. The conditions, by the way, are designed to protect the purity of the R-12 supply. The longer we have pure R-12, the less disruption there will be for consumers. They include unique fittings to prevent cross-contamination, labeling, and prohibiting topping off R-12 with another refrigerant. It's still legal, at least under federal law, to top off R-12 with R-12. So the use conditions take effect for each refrigerant on which we impose them. We first proposed the use conditions on FRIGC, R-134a, and R-401C last September. We took comment, and then published the rule on June 13. That's the same rule that contains the passage I discuss below. In order to find R-406A acceptable subject to the same use conditions, it will take a similar period of time. The mfrs. of R-406A very strongly wanted people to voluntarily obey the use conditions until they became formally required. However, on June 13, 1995, we published a rule that said that "flammable refrigerants, defined as having flammability limits as measured according to ASTM E-681...including blends which become flammable during fractionation, are unacceptable as substitutes for CFC-12 in retrofitted motor vehicle air conditioning systems." We took the action in June because flammable refrigerants had previously been marketed without sufficient analysis to show they can be used safely. I know there are people who disagree with our decision, and I'm not going to try to explain it in detail here. I'm just telling you why we found all flammables, and blends which become flammable, unacceptable. R-406A, when it leaks a lot, does become weakly flammable. We didn't reverse an EPA decision. What we did was to alert the mfrs. of R-406A that a prior ruling does apply to that refrigerant, and that therefore it's unacceptable for use a retrofit in cars. There's no conspiracy against anyone, and there's no undue outside influence. Now, if a good risk assessment is done to demonstrate that the weak flammability R-406A exhibits after high leakage presents a small risk, we can still find it acceptable subject to those use conditions. And, in fact, the mfrs. did conduct a risk assessment, and we're reviewing it now. So it's still possible that as of next Spring or so, we could list it as acceptable subject to use conditions. It would then be in the same category as FRIGC, R-134a, and R-401C. For purposes of completeness, though, I must say it's also possible we'll find it unacceptable. So, we didn't reverse ourselves. We never made a ruling that it would be legal for sale in September, since that's just the default written into the Clean Air Act. What we did was point out to the mfrs. of R-406A that a prior ruling applies to it. If you've read this far in the post, I hope this clears things up. Jeffrey Levy - USEPA Call our hotline at 800-296-1996 for fact sheets and pamphlets related to the science and regulation of protecting the ozone layer.
Subject: Re: R-12 replacement From: firstname.lastname@example.org (George Goble) Message-ID: <email@example.com> Date: Mar 27 1997 Newsgroups: rec.autos.tech In article <firstname.lastname@example.org> email@example.com (Willem-Jan Markerink) writes: >In article <firstname.lastname@example.org>, > "Tom Graham" <email@example.com> wrote: >>> R12. It's not to say that blends will be forever unacceptable, >>> perhaps they will. But, the industry has yet to embrace them and it >>> doesn't seem likely that they will over the near term. As you >>> mentioned, there is the problem of getting systems fitted with blends >>> serviced but there is also the problem of warranty. As far as I >>> know, no OE or aftermarket >> >>Good point re auto industry. However, commercial, "stationary" systems >>have adopted some blends (406a I think), so I've been told, with >>enthusiasm because they are more efficient than even R12. This >>translates into significant dollars saved for commercial buildings. >>This is what I've heard, no direct knowledge though. Would be happy to >>hear from anyone with direct knowledge re this. >>Tom Graham > >406a is indeed claimed to be up to 30% more efficient than R12, whereas >R134a is claimed to be 30% less efficient than R12. >So my favorite would be a system designed for R134a (larger than R12), >filled with 406a....with some risky assumptions, that's about 70% more >effective/efficient(?)....8-)) I never claimed R406A (e.g. Autofrost) was 30% more efficient than R12. It depends on the car (system type) and the conditions. R406A usually results in a faster initial cooldown than R12 (more capacity).. which is what people notice.. CCOT type systems (e.g. GM) can have 6-10F colder duct temperatures. Expansion valve types (e.g. Honda) can be 2 or 3 degrees colder. Due to the "glide" (multiple boiling points), R406A moves more heat than R12 or R134a. Older cars, with marginal radiators (mostly plugged), had engine boilovers after recharging with R406A, since the greater amount of heat moved from 406A leaves the condenser and gets sucked thru the radiator, causing it to boil over if it was marginal to begin with. The guy is right about putting R406A in a system built for R134a on the huge increase in cooling capacity.. Word of caution: R406A is designed for oils used in R12 systems (mineral oil or alkylbenzene). Most PAG oils (for 134a) will be destroyed by 406A, R12, or most other blends since they contain some chlorine atoms. POE oils (another 134a oil) may be thinned excessively by 406A and other HCFC blends. Anybody changing over a 134a system to 406A, R12, or another blend, should flush it thoroughly with a good solvent, and remove the compressor, and put it on the bench and hand turn it about 50 revs while pouring mineral oil into the intake to work out PAG oil first. Change the drier back to Xh5 or Xh9 desiccant. There are compressor remanufacturers that buy skids of R406A. --ghg, inventor of R-406A/Autofrost
Subject: Alternative Refrigerants / Lubricants / R-134a From: firstname.lastname@example.org Message-ID: <email@example.com> Date: Jun 24 1997 Newsgroups: rec.autos.tech,rec.autos.misc It is well known from the literature, that chlorine adversely affects the stability of Polyalkylene Glycol (PAG) oils used in R-134a systems, both new and retrofit. The chlorine may come from residual R-12 (or R-11 flush), or aluminum chloride coatings (not possible to flush out) formed on the inside of aluminum parts from when R-12 was previously installed in the system. If small amounts of R-11 (more active than R-12 in the destruction of PAG oils) after an R-11 flush when retrofitting (or from prev R-12 servicing) to R-134a, engineering test stands have had compressor failues in as short as a week from PAG oil breakdown. Residual chlorides from R-12 and pipe coatings may not destroy PAG oil in a week, but often after several months it will begin to break down. There is only one new PAG oil on the market (recent times), which claims they can tolerate large amounts of chlorides, I think it's brand name is "Daphne". I have no actual test results, either way on it though. When you service a R-134a car, the chances are that it does not contain Daphne oil though. Literature ref. to some papers about effects of chlorides on PAG oils. This list is by no means complete, but can serve as a starting point. S. Yokoo, K. Doi, T. Takano (Nissan Motor Company, Limited, Japan), and T. Kaimai (Kyodo Oil Technical Research Center Company, Limited, Japan), "Development of a Lubricant for Retrofitting Automotive Air Conditioners for Use with HFC-134a", Climate Control and Automotive Cabin Air Filtration, publication SP-1040, Society of Automotive Engineers (SAE), Warrendale, PA, pages 57-61 1994; republished as paper 940594 (SAE International Congress and Exposition, Detroit, MI, 28 Feb - 3 Mar 1994), SAE, 1994. C. Powers (Robinair Divison of SPX Corp) and S. Rosen (Consultant), "Compatibilty Testing of Various Percentages of R-12 in R-134a and PAG Lubricant", unpublished presentation at the International CFC and Halon Conference, Washington, DC, 30 September 1992. "Polyglycol Sealed-Tube Tests", Carrier Corporation, Syracuse, NY, September 1989. [reported that R-134a and two PAG lubricants (Nippon RS680 and Glygoyle 11) that no decomposition was detected for R-134a, but R-12 decomposition was 75-90% with both lubricants] A. D. Nickens, G. F. Brunner, and D. L. Hamilton (US Navy), "Navy Investigations of HFC-134a as a Replacement for CFC-12 in Shipboard Applications", Naval Engineers Journal, pages 98-103, May 1992. "Factors Affecting the Copper Plating Phenomena with HFC-134a/ Polyalkylene Refrigeration Fluids (Focus: Mobile Air Conditioning)", report ARTD-32 (H-35800), DuPont Chemicals, Incorporated, Wilmington, DE, undated circa 1993. S. Corr, E. Goodwin, R. D. Gregson, A. Halse, A. Lindley (ICI Chemicals and Polymers, Limited), S. H. Colmery, T. W. Dekleva, and R. Yost (ICI Americas, Incorporated), "Retrofitting Mobile Air Conditioning Systems with HFC-134a", seminar presentation at the Society of Automotive Engineers (SAE) Passenger Car Meeting and Exposition (Nashville, TN), ICI Americas Incorporated, New Castle, DE, USA, 18 September 1991. --- Any refrigerant or blend containing a "CFC" or "HCFC" (stands for Chlorofluorocarbon and Hydrochlorofluorocarbon) contains chlorine atoms and may be detrimental to PAG lubricants used in R-134a systems. "HFC" means hydrofluorocarbon (e.g. HFC-134a) and contains no chlorine. In order to use a chlorinated refrigerant (see below table) in a R-134a system containing PAG oil (unless you have Daphne PAG), one must take apart the system, and use a suitable flush to remove *ALL* the PAG oil. Then remove the compressor and place it on the bench, and dribble mineral oil (Ford part # YN9 is a good choice) into the compressor intake while turning it over 40 or 50 times to work out the PAG oil. The drier should be changed to XH5 or XH9 desiccant if it is XH7 (134a only) desiccant. Recharge with a chlorinated blend or R-12. The following refrigerants and blends contain chlorine, components (weight %) name R12 CFC-12 100% (dichlorodifluoromethane) R22 HCFC-22 100% (chlorodifluoromethane) R142b HCFC-142b 100% (chlorodifluoroethane) R124 HCFC-124 100% (chlorotetrafluoroethane) R406A/Autofrost-X3 HCFC-22 55% / HCFC-142b 41% / Isobutane 4% R414A/Chill-it/Autofrost-X4/GHG-X4 HCFC-22 51% / HCFC-124 28.5% / HCFC-142b 16.5% / Isobutane 4% FRIGC FR-12 HFC-134a 59% / HCFC-124 39% / Butane 2% FREE ZONE RB-276 HFC-134a 79% / HCFC-142b 19% / lubricant 2% Freeze 12 HFC-134a 80% / HCFC-142b 20% HOTSHOT/R-414B HCFC-22 50% / HCFC-124 39% / HCFC-142b 9.5% / Isobutane 1.5% Compositions listed on the US EPA web page http://www.epa.gov/ozone/title6/snap/macssubs.html In addition, the ARTI refrigerant database (see www.ari.org for info) lists an "unassigned blend" of composition HCFC-22 55% / HCFC-124 24% / HCFC-142b 18% / Isobutane 3% and states "This blend was marketed by ICOR International, Incorporated (Indianapolis, IN, USA) and others from late 1995 through March 1996 under the name "HOT SHOT". This product was reformulated to settle a claim of patent infringement". Now, look at the composition of R-414A / GHG-X4. Some manufacturers and sales reps claim that their chlorinated refrigerant blends can be "dropped into" R-134a systems without regard or concern for the breakdown of PAG oils used in R-134a systems. Nor do they say anything about removing said PAG oils before installing their products. ------ Oil miscibility (in mineral oil). A refrigerant and oil must be "miscible" in each other (dissolve in each other) to a degree such that mineral oil (as found in R-12 systems) circulates through the system correctly and returns to the compressor. Using HFC-134a refrigerant in mineral oil (R-12 systems), without changing the oil, results in a non-miscibile condition, and the oil will eventually migrate to the evaporator in a large number of systems and starve the compressor for oil, and it will fail. R-406A (Autofrost) and R-414A (Chillit / Autofrost-X4) were developed and extensively tested for oil return capabilities using standard mineral oils as used in R-12 systems (no oil change is needed). Stationary systems were tested down to about -50 F and Automotive systems down to about 0F for oil return and found to work fine in engineering oil test stands and real life systems. Development on what became R-406A was begun in August 1990. Both Isobutane and HCFC-142b were needed to achieve proper operation of returning mineral oil to the compressor so an oil change was not needed. It was discovered during testing in 1990, that lowering the isobutane content below 2.5% or so, did not provide adequate oil return, and this is reflected in the claims of (my) US Patent No. 5,151,207 which covers R-406A and R-414A. Some manufacturers have chosen to sell products which operate just outside the limits of the above patent by having less than 2% isobutane and less than 15% HCFC-142b needed to adequately return mineral oil to the compressor in all systems. Refrigerants with less than 2% isobutane and less than 15% HCFC-142b may work fine in *SOME* or *MOST* systems, depending on how much oil is present, the diameter of the suction lines, and the length and whether or not the suction line is level, uphill or downhill to the compressor. One will not know if these refrigerants will work in the long term (it may take a month or two for oil to migrate out of the compressor) until a compressor failure occurs and a teardown shows a "dry" compressor. These refrigerants will generally work ok, if most or all of the oil is changed to alkylbezene type oil, which is miscibile in R-124 and R-22, whereas mineral oil is only mediocre in R-22 and very poor in R-124. Without R-142b, even 5% isobutane does not provide sufficient oil miscibility to return oil to the compressor. A test was tried with R-134a and mineral oil, and 5% isobutane was added, and oil return was still miserable. (525 SUS viscosity Automotive compressor oil) ------- Performance R-134a has a couple of problems, when used in a system designed for R-12. Firstly, the boiling point of R-134a is about -15F compared to R-12 at -21.6F. (at one Atmosphere).. This causes 4 or 5 degree warmer duct temperatures unless the system is modified by setting low pressure cutout lower to compensate. Variable displacement compressors, such at the GM V5 are difficult or impossible to modify, and always set the suction pressure at 28 PSIG. R-134a has a lower "critical" temperature (214F) vs 233F for R-12. The critical temperature of a gas is the the temperature at which as gas will no longer condense to a liquid, no matter how much pressure is placed upon it. When under the hood/condenser temperatures approach the critical temperature of a refrigerant, head pressures soar, and cooling performance goes down the tubes. Under the hood temps of 220F are not uncommon. Other manufacturers market blends comprised primarily of R-134a and are "cut" with either R-142b or R-124, both of which have higher (warmer) boiling points than R-134a. R-12 boiling point -21.6 R-134a boiling pt -15 R-124 boiling pt +10 R-142b boiling pt +14 So, how is adding 20% - 40% of R-124 or R-142b going to make the refrigerant any colder than R-134a is already without having a "balancing" ingredient in the colder direction? R-406A contains 55% R-22, and R-414A contains 51% R-22 to produce a correct temperature-pressure relationship which closely tracks R-12 and doesn't require changing the oil nor the pressure controls. R-22 boils at -44F. It has also been discovered, that blends with approximately a "glide" of about 15 deg F, extend the "phase change" area (the area where boiling or condensing is going on) in the evaporator or condenser. These components are better utilized, resulting in more heat transferred, which shows up as a faster cooldown when starting up the A/C in a hot car. One has to be sure their radiator/cooling system is in good shape though, as the extra heat rejected out of the condenser with R-406A/R-414A has caused radiator "boilovers" in cars with dirty/plugged radiators, since the radiator is just behind the condenser. --George Goble (ghg), inventor of R-406A/R-414A/Autofrost/Autofrost-X4/ Chillit/McCool/GHG-HP refrigerants and holder of US Patent no. 5,151,207. President, GHG DEV Labs, Inc. http://worldserver.com/autofrost email: firstname.lastname@example.org
Date: Wed, 27 Aug 1997 06:11:21 -0600 From: email@example.com Message-ID: <firstname.lastname@example.org> Subject: Re: R-406A & 409A Newsgroups: sci.engr.heat-vent-ac In article <19970825030401.XAA20447@ladder02.news.aol.com>, email@example.com (Jimabate) wrote: > From firstname.lastname@example.org > Subject: R-406A & 409A > > I converted 11 E-400 Manitowoc ice machines from r-12 air cooled to 409A > watercooled. The condenser water is a chilled water loop. > Anyhow, I noticed that the compressor discharge temperature and the > discharge superheat were very high. I assume, maybe wrongly, that the high > concentration of R-22 in this blend contributed to the high discharge > temps. I was able to lower the condensing temperature low enough to > mitigate the problem on the ice machines. > Then I converted 2 med. temp reach in boxes to r-406A. The line set was > about 30 feet to the remote condensing units. With normal pressures, these > air cooled units had discharge temps approaching 220 degrees, and over 100 > degree discharge superheat on both units. > The compressors were practically glowing hot. I adjusted the TXV valves to > obtain the lowest suction superheat possible without killing the > compressors. Only when the valve was adjusted so low that a "wet" vapor > returned to the compressor, did the discharge temperature (and superheat) > come down to acceptable levels. > It has run for 3 months like this and seems OK. > With the wet return there was a considerable increase in run time, I > assume again, that the compressors must be refrigerated along with the > box. > No, I did not charge the refrigerant in as a vapor causing fractionization > of the blend. > I'm not bad mouthing these refrigerants, just looking to start a thread so > I can fully understand what operational quirks these refrigerants have. > If you really need exact temps & pressures I will pull out my reports. > > My question is simply this: > Does anyone else experience simular problems with any of these blends? I am the inventor of R-406A. R-406A and similar blends have been in use since Aug 1990. You are correct in the fact that R22 in blends cause an increase in compressor discharge temps, a fact of life. That is why R502 was invented. You are also correct in that adjusting the TXV (or the charge in cap tube units) to provide compressor cooling from the suction return gas. You can even run ice machines and reach-ins, with frost almost back to the compressor (but not covering the compressor shell). This is good practice with R-12 and other refrigerants as well. As long as the measured discharge temps at the compressor discharge line are less than 240F, you should be ok. This equates into approx 280-290F in the discharge valves. 300F starts approaching the temps where R22 will breakdown and must be avoided. There is approx a 1 to 1 reduction in discharge temp for each degree the suction gas temp is reduced (keep at least 10-20F of suction superheat though) On the systems with the 30 foot lines, the suction line should be insulated. This way, you wont be wasting capacity cooling the room, while still being able to cool the compressor. The main advantage of R-406A is that is miscibile (dissolves in) mineral oil and returns it to the compressor without problems down to at least -50F. R-406A contains 55% R22 / 41% R142b / 4% isobutane (R600a), not enough to be flammable, but this causes excellent oil return. FX-56 (R-409A), contains only 15% R-142b (60% R22, 25% R124) and does not return mineral oil very well in all systems at all temperatures. Atochem (FX-56 mfgr) states that Alkylbenezne oil (AB) may have to be added to ensure oil return in some systems. R22 and R142b are at best only "mediocre" at returning mineral oil. At least 15% R-142b AND 3% isobutane are needed together to ensure good oil return it was discovered in engineering oil-return test stands build for testing oil return properties. This is a two ton low temp refrigeration circuit, with large (vertical) suction lines and long line runs, with bunches of sight glasses all over the evap and suction lines for observation. FX-56 (R-409A) offered almost no mineral oil return below 32F (150 SUS mineral oil), whereas R-406A went down to -50F. A few degrees before oil return starts to fail (oil return becomes more difficult as the evap temp drops), the oil/refrigerant mixture in the evaporator starts to look "milky". This is due to the oil not dissolving in the refrigerant anymore, but forming a fine dispersion instead. Some systems like refrigerators have a downhill run from the evaporator to the compressor and may not need any oil miscibility to return the oil. These systems will work even when charged with R-134a (in mineral oil!) Other systems will just "log oil in the evaporator" and lose performance if oil does not return properly. Still other systems, notably automotive compressors only contain 5-8oz of (thick 525 SUS) oil, and a poor oil return refrigerant will cause the compressor to lose all oil and fail outright. Lots of technical info on www.autofrost.com about R-406A (Autofrost as the trade name for R-406A in the Automotive industry) R-409A contains R-124 (R-406A does not), that was recently implicated in a problem with human liver damage. See next post for more info on that. --ghg, R-406A/R-414A/GHG-HP/GHG-X5 inventor.
Subject: Re: An Alternative to Retrofitting to R-134a - why blends work From: email@example.com Message-ID: <firstname.lastname@example.org> Date: Jun 21 1997 Newsgroups: rec.autos.tech In article <email@example.com>, firstname.lastname@example.org wrote: > In article <B47F9276D0B14F69.4416ADBB663DA1FC.382C9E6FA9C7B80B@library-proxy.airnews.net>, > pjh@DELETE-ME.radiks.net (P.J. Hartman) wrote: > > > > email@example.com (JBlessing) wrote: > > > > >In article <33A691E6.54F1@mail.idt.net>, firstname.lastname@example.org says... > > >> > > >>I read in Hanyes that 134a is significantly lower > > >>performance than R12 . I believe it . > > > > > > > > >And of course haynes is ALWAYS right, hehe. > > > > I'm certainly not fond of our "friend" altavoz, but I do believe that > > he's right this time. All that I have read indicates that R134a moves > > less heat per unit than does R12. This would certainly mean less > > efficient. > > > > George Goble, inventor of R-406a and other refrigerants, agrees that > > R134a is less efficient than R12. > > Really the question should be one of R134a performing well in systems > designed around R-12. If a system retrofitted to R134a gives adequete > performance than the relative efficiency of R134a versus R-12 is a moot > point. There have been many sucessful R134a retrofits done on R-12 > systems where there has been no observable loss of performance and in > some cases such systems actually worked better after the retrofit was > done. The problem with R-12 substitutes such as R406a and FR-12 is that > they are blends based on R-22 or R134a. The MVAC industry has been > reluctant to support blended refrigerants because the question of > "fractionation" where lighter components of the blend tend to escape the > system first thus altering the blend ratio to the point where system > efficiency is seriously compromised and pressure/temparature ratios > within the system could get to the point where possible damage could > occur to system components such as the compressor. R-12 and R134a are not > blends but are instead homogeneous substances so fractionation is not an > issue. The MVAC industry so far will only warranty new or rebuilt MVAC > components when used with R-12 or R134a because the long-term durability > of blended refrigerants in MVAC applications is not well understood at > the present. Perhaps the MVAC industry will eventually endorse blended > refrigerants, but they haven't so far and as such I can only recomend > that R-12 or R134a be used in servicing MVAC systems. > > ........Fred "Fractionation" is what is right with R-406A/Autofrost. The "glide" is about 15 degrees F. This causes the "phase change" area to become much larger in the condenser (to reject heat) and the evaporator (to accept heat). Single component refrigerants, like R-134a, waste large areas of the condenser cooling down "hot gas", and "liquid" -- operations which reject a relatively small amount of heat compared to the phase change region. This enables R-406A/Autofrost/R-414A/Chillit to move much more heat than is possible in R12 or R134a systems. Check out http://worldserver.com/Autofrost/info for detailed explanations of all this. R-406A/Autofrost & Chillit often produce 6-10 deg F colder duct temps (on max fan) than does R-12.. R-134a can't hold a candle to that in almost all systems. These blends contain enough R-142b and isobutane to properly circulate R-12 mineral oil and dont need unstable mositure sensitive POE (ester) oils added. There are some compressor makers or distributors who warranty compressors (both stationary and MVAC) with R-406A/Autofrost, etc.. and some who don't. If the maker or distributor of a compressor chooses not to warranty it with R-406A, etc, Monroe Air Tech will warranty it. Compressor failures are just not a problem with these refrigerants. Variants of R-406A/Autofrost have been run in MVAC systems since 1990, long before EPA SNAP, the 134a based blends existed and long before 134a became "common". --ghg, inventor R-406A/Autofrost/R-414A/Chillit, GHG-HP, and others soon to be announced.
From: email@example.com Message-ID: <firstname.lastname@example.org> Newsgroups: rec.autos.tech,austin.autos Subject: Re: R134A refrigerant Date: Sun, 19 Jul 1998 19:25:47 GMT In article <35AE26B2.41C6@the.sig>, "S.L." <email@example.com> wrote: > firstname.lastname@example.org wrote: > > > > > > > Questions still exist on the compatibility of R-22 with components > > used in vehicular A/C systems. Nitrile or HBNR rubber hoses are > > definetely not compatible with R-22 although neoprene appears to be, > > but R406a definetely is NOT a drop-in replacement for R-12 anymore > > than R134a is. > > True... there IS NO DROP IN replacement, which is why I favor sticking > with R-12. R-406A "used to be" a drop-in for most vehicles (1990-1993), GM good hoses (non nitrile), etc. We even got a letter from Jeff Wells at the EPA (external division, helping foreign countries) stating that R-406A was a "drop-in". Ward Atkinson of MACS lobbied thru the EPA the rule making the term "drop-in" illegal in SNAP refrigerant use. Since they now all need "EPA fittings" to be legal, nothing can be a "drop-in" in the US, since the fittings must be added now. We have had fleet owners, going to shops, after an R-12 to R-406A conversion, and had their entire fleets changed over to R-406A due to better performance. Much of the success is due to the experience and methods of the airshop. Such as good vacuums, knowing when to change a hose or o-ring, etc. most DIYers will get into trouble with about any refrigerant. > > Many newer cars have barrier or poly lined hoses > > anyway, so hoses may not have to be changed, but you'll have > > to change the O rings, pull the compressor, get it on the bench, > > and change the seals. > > You have to do all that PLUS flush out all the oil to go to R-134a. The > labor involved also depends on the compressor. If you have a Sanden or > Nippondingdong (er... NipponDENSO :-) compressor, you are in for a seal > change but you also have the option of just replacing the compressor > with an R-134a capable version, which will also work fine with R406, > Fr12, or any of the other substitutes. If you have one of the old York > (Ford, VW, aftermarket) or Chrysler reciprocating compressors, you can > do a seal change without removing it from the car- its extremely easy. > If you have an old GM or Harrison compressor... well no old GM > compressors are still working anyway ;-) My GM compressor (V5) is still working from 1992. > > The desicant cylinder, of course, need to be > > changed, but questions remain about the compatibility of XH-7 > > desicants with R-22. XH-9 is ok, but not widely available. So > > from a "sweat equity" standpoint, an R406a retrofit is just as > > labour extensive as a R134a retrofit. > We haven't seen any problems with R-406A in XH-7, but it will absorb less moisture than XH9 or XH5. XH9 was going to take over the market as the "universal" dryer for all refrigerants, but the auto industry quickly realized that this would help the blends, so they got XH9 stopped everywhere they could, trying to do a PR campaign to corral people into the 134a pipeline. UOP (desiccant maker) told me that small amounts of residual moisture "protect" the donut molecular sieve molecules from being degraded by R22, etc. OF the XH7 is totally "dry", in a lab, R-22 will degrade it. In practice, there is always some moisture. > Sweat equity during the retrofit is indeed the same... but you'll > definitely keep sweating afterward with R-134a, because the system will > take a big efficiency hit ;-) > > > As far as system pressures > > go, R406a, like R134a will cause higher pressure, > > I don't think so. R-406 certainly won't push the high side up around > 300psi like R-134a can. It depends on temperatures on the condenser. > > but being that > > the R-22 component of the blend has the highest temparature/pressure > > ratio of the three refrigerants used in the blend, it will tend to > > escape the system first. Another question is what happens to be > > blend when the system is in a quiescent state, i.e. not used. > > Does the blend fractionate with the heavier components settling > > in the lower spots and the lighter ones above it? > > My understanding is that the *gaseous* part of the charge will change > composition, being dominated by the lightest part of the blend. However, > the *liquid* portion does not significantly alter composition and > doesn't separate into layers (the blend components all dissolve into > each other- just like alcohol and water don't separate as a liquid mix), > and the vast majority of the charge (in terms of weight, not volume) > stays liquid with the system off. > > >On start-up, > > this could cause abnormal pressures until the blend is reconstituted > > through normal circulation. The liquid portion stays mixed well, when the system is off as it does in cylinders. When the system is running, fractionation (composition changing) happens a great deal in the condenser and evaporator. This greatly expands the "phase change area" in the condenser (the region that rejects the most heat). Now most of the condenser can reject more heat, whereas single component refrigerants only have high heat rejection in a smaller part of the condenser. THis is why R-406A/Autofrost can move more heat than R-12 or -134a, and yet not freeze up the evaporator. One side effect though, is that if the radiator is not in good shape (partially clogged), that running the A/C will cause the radiator to boil over, since all the extra heat comes out of the condenser and goes into the radiator. > Indeed. Supposedly it takes about 1-2 minutes for the system to > stabilize, but no *harmful* pressure spikes happen during stabilization. > Pressures tend to be a bit too low until the system stabilizes, and that > doesn't hurt anything. THe real overpressures to worry about, happen 30 to 45 mins AFTER the car is stopped. The radiator/engine "heat soaks" the condenser, and all the refrigerant "heat pipes" to the evaporator, which heats up, and since no air flow, it gets hotter and pressures rise. > >This leads to another question, if the > > blend fractionates when stored, precautions would have to be > > undertaken to make sure the blend ratio is correct through all levels > > of handling and distribution. > > That one is easy. ALL blends should be transferred from > container-to-container and from container-to-system as *liquids*. This > guarantees the correct ratio, because in the liquid state the components > stay mixed (dissolved) in each other. This is true. THis is checked by a GC (Gas chromatograph), and "pressure-temperature" checks. (read the pressure at a known temp). > > > So if we take a typical car that normally delivers 40 F discharge > > air in 90 F ambient air with the vehicle stationary with a properly > > functioning R-12 system. We convert it over to R406a and the discharge > > air plummets to 31 F until the evaporator ices up and the compressor > > cycles off. After 5 minutes, enough ice is melted off to allow air > > to pass through, the compressor kicks back in and the process repeats > > itself. In the meantime, the occupants get hot and stuffy. > > That shouldn't happen. The cycling switch WILL cut the compressor off > before enough ice forms to block airflow and cause the problem you > describe. On cars without cycling switches, the EPR valve still holds > the evaporator at a constant 40 degrees because the pressure curves of > R406 are the same as R-12. The only systems that would suffer icing are > the cheap-o aftermarket underdash units that don't have EPR or cycling > switches... they already turn to ice blocks using R-12! I once invented a refrigerant, GHG-HP, similar to R-406A, but delivered 25F duct temps on max recirc (10% more R22) at 95-100F ambient, humid. Evaporator ran at about 18-19F, whole suction line back to the compressor frosted up. THe accum was a "ball of ice" after a road trip. It felt good. It would take 8-10 mins or so for the evaporator to start to freeze. Running the evap fans for 15-20 seconds, with the compressor off (a GM V5 cont run compressor) easily cleared the ice out. Cycling systems would probably melt out if off for over 15 seconds in 5 mins. GHG-HP is even EPA SNAP acceptable and was intended for harsh areas such as south Texas and Florida. GHG-HP had several test cylinders made up and it worked well, but the hassles of having to deal with "defrost" timers and our customers said that R-406A worked well enough for them, we never marketed it. From www.aircondition.com, it seems that south Texas preferrs Freeze12 instead.. cheap, 10-12F warmer than R-12 and poor at returning mineral oil. The two people around here who used Freeze12 both lost their compressors after 2-4 months of running. > > I agree there, stay with R-12 as long as it is still available. If > > you need a major overhaul of the system, retrofitting should be considered. > > True, and I agree that you are asking ALL the right questions about > alternative refrigerants. The only way to pick the right one (if you > must pick one) is to *understand* what effects they will have, because > none will make the system work *exactly* the same as it did with R-12. Some make your system work better. > What I hate to see are those $15 "R-134a retrofit kits" hanging on the > shelf in cheesy parts stores everywhere. People are excessively focused > on the low initial price of R-134a, so they think those kits are the way > to go and they don't realize that a good, reliable, WORKABLE conversion > costs hundreds of dollars. Look at all the changes OEM's made when they > went to R-134a (taken from my wife's 1993 R-134a- equipped car's factory > service manual): > > - new compressor with teflon coated pistons > - significantly tighter compressor tolerances > - larger compressors for the same BTU rated system > - 10-20% larger condensors for the same size evaporator > - Parallel-flow condesnsors instead of serpentine > - 20-50% greater condensor fan capacity > - PAG oil (good stuff, but disintigrates if even a TRACE of R-12 touches > it!) > - eliminated ALL copper and steel from the system > - Barrier hoses, neoprene O-rings > > They didn't do all that just because it was fun. They did it so that an > R-134a system would have a hope of surviving to 150,000 or 200,000 miles > and they wouldn't lose their shirts on warranty claims (and they've lost > quite a bit anyway)! As I said, I have an R-134a OEM system, and it > works just fine at over 120,000 miles so I know all those changes worked > to some degree. The kits make it sound simple... but I've read the > instructions on the packages and I've looked at the oils and "stop > leaks" they supply with the kits. I GUARANTEE you that if you use one of > those kits according to the instructions, you will have a completely > RUINED A/C system within 2 years... maybe even within 2 DAYS, especially I will second that. POE (ester) "Universal" oils can be unstable compared to the R-12 mineral oils. We always reccommend Mineral oil for R-406A, but many customers say it works in Esters (POE).. we think those will have shortened lives, due to lower lubricity, no foaming, and other POE oil problems. Don't even think of putting R-406A into PAG oil, it will self destruct unless the oil is "Daphne" and no long term data on Daphne when run with R-12 or other chlorinated refrigerants. > if you live in the south where A/C is needed nearly year-round. I've > seen LOTS of posts to www.aircondition.com/ wwwboard/retrofitting/ that > say "Help- installed retrofit and it worked for a week...." so true. > -- > Stephen Lacker > Applied Research Laboratories, The University of Texas at Austin > email@example.com (Remove the extra 'x' to mail me) > --ghg, www.autofrost.com, inventor R-406A/Autofrost, GHG-X7, GHG-HP