I Want to ask about R404 ,
I listen many people say that if you want to recharge some R404 in your system you have to change all the refrigerant.
Is it true ?
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I Want to ask about R404 ,
I listen many people say that if you want to recharge some R404 in your system you have to change all the refrigerant.
Is it true ?
No, it's not. Fractionation of R404a is negligible and therefore there is no need to change all of refrigerant.Quote:
Originally Posted by Giannis
R407c is example of such need.
Nike123
sorry mate I think are wrong on this one, in the event of a leak on the vapour side of the system on a low temp application and you do not replace the whole charge the system will not come down to temp. If there is no problem with fractionalisation why do we need to take the refrigerant from a bottle as a liquid, if there was not a problem we could take it as a liquid or a vapour as per R502.
Ian
If you are afraid of fractionisation use R507 R404a and some drop ins (R69L) will fractionate.Quote:
Originally Posted by nike123
I have seem the effect in both refrigerants, vast amounts of hp used with poor freezing. In one plant I re charged with R22 when all the R69L had leaked out, the plant was very poor on the 69L but received a new lease of life on R22, constant low side leaks over the years were the reason.
The reason I changed to R22 was to save money, with the refrigerant charge, with the effect of saving running costs too.
Kind Regards Andy:)
Kind Regards
It's near-azeotrope blend and some sources said that is possible to top-up R404A and R410A (of course in liquid phase) without danger of considerable change in composition.Quote:
Originally Posted by Pooh
I have very little personal experience with R404a because, we, here in Croatia, still servicing our plants with R22 and R12 and, I personally, evacuate and charge new R404a in new systems when I servicing them (main reason is because that is more work and material to charge:o).
I ask for which oil used for r404a mineral or syntheticand why ?
Synthetic:)Quote:
Originally Posted by m3ae2002
Mineral oil reacts with the HFC air and moisture to create an acid.
Kind Regards Andy:)
Interesting answer to the problem there Andy. Retro-fiitting R22 to a system filled with a Retro-fit gas! (R69L) Am I correct in thinking that R69L was the drop-in for R502?Quote:
Originally Posted by Andy
Also in requires a larger Condenser because for the same duty it runs with higher discharge pressures / temps?
Therefore does it work the other way? By changing to R22 ( The Condenser has spare capacity) and I presume the saving was due to running at lower discharge temps?
Do you favour a particular drop-in for R22 yet?
Interesting note.. I phoned Tech Support at Isceon once, asking about charging a system by weight ( critical charge). I was told take the R12 charge weight and reduce it by 10%. (replacing with R49L)
Has anyone else heard of this?
Grizzlyhttp://www.refrigeration-engineer.co...ons/icon14.gif
ADENDUM: Thanks Andy I have just realised we have a site with very similar problems to the one you describe. Where your mod may well do the trick!
The only problem is how could I justify changing to R22 when we should be starting to phase it out. Any ideas anyone?
Grizzly
I agree with you, how can anyone warrant charging a system with R22 in todays environmentally concious society no matter what the economic benefits are. I know that in the UK it is OK to recharge an existing system with R22 but I do not think it would be deemed OK to retrofit a system to R22 especially from a refrigerant that is seen as more environmentally freindly than R22, a bit of a retrograde step in my eyes. Also would it not have been more sensible to sort out the leaks that had caused the original refrigerant to fractionate and then stuck with that refrigerant.
Ian
Pooh.Quote:
Originally Posted by Pooh
I was not critisizing Andy, I think it was a clever move. Just one that we can no longer adopt.
Andy did not say when it was done?
One thing puzzles me! Don't the majority of these
replacement refrigerants have smaller molcules than the ones they are replacing.
Most of the larger R22 systems I work on have open drive compressers, with shaft seals.
Because of long low load cycles, non cycling of lead lag or whatever. A Compressor shaft seal could dry out and start leaking.
With a R22 system which does not fractionate the
efficency of the system is only affected when working level / pressures are low enough.
The levels were restored by the engineer and alls well.
In my opinion the problem is compounded because the replacements have smaller molecules and therefore even a gas tight R22 system may leak once retrofitted.
Also as Andy stated small fractionated leaks are harder to deal with and long term more dissruptive to plant efficency.
An even greater problem is some refrigerants have molecules that are smaller than the Nitrogen we are using to detect their leaks with!
Has anyone come up with a viable alternative and how big are their molecules?
Grizzlyhttp://www.refrigeration-engineer.co...ons/icon14.gif
ADDENDUM. Is the molecule size and therefore the ease at which we can detect system leaks not something we should be considering. It can be nigh on imposible to detect some leaks nowadays!
GrizzlyQuote:
Originally Posted by Grizzly
I too was not critising Andy, however there are people on the forum that may take his comments out of context and go down the same route as an easy option.
If you were to speak to anyone who knows me well they would say that there is nobody more against the so called environmentally freindly refrigerants than me, they as you point out have in the case of R134a a molecular size one tenth of that of R12 and are less efficient as a refrigerant also the oil they need requires more refining and thus more energy usage.
Take the issues with the zeotrolic blends into account and in my mind we have gone backwards nearly one hundred years. If I had any input into the whole refrigerant issue I would bring back R12, R22 and R502 BUT put in place sufficient controls on their usage to keep losses to a bare minimum, surely this would overall reduce the effect of refrigerants on the environment. At the end of the day the refrigeration industry used less than 1% of the CFC's produced (if my memory is correct) and we released less than 20% of that as it has always been in our favour to keep the stuff in the system. If you take that 80% of the R134a produced is already in the atmosphere we may as well go back to the CFC's at least we could find leaks easily and keep it in the system were it needed to be.
Ian
OFF the soap box now.
POOHQuote:
Originally Posted by Pooh
I Agree, well said isn't it time we all started asking how well informed are these tree huggers that are making the policies we have to work to.
I think we may stand a chance if we all said this more often.
good for you.
Meanwhile.... is it just me that finds it hard to leak
check the newer refrigerants?
Grizzlyhttp://www.refrigeration-engineer.co...ons/icon14.gif
Grizzly
no it aint just you even with a decent electronic you still cant find them.
Ian
Member of the BRING BACK THE HALIDE LAMP PARTY
Hi Grizzly,
There have been a few discussion on leak detection which may be of interest to you; unfortunately no easy answers yet I believe.
http://www.refrigeration-engineer.co...ight=leak+test
Brian.Quote:
Originally Posted by Brian_UK
Thanks for the link. I guess Andy's the nearest with those threads. I had heard that you could buy from BOC. A Nitrogen blended with something to facilitate
easier leak checking.Though ive not tried it yet.
Grizzly
PoohQuote:
no it aint just you even with a decent electronic you still cant find them.
Ian
Member of the BRING BACK THE HALIDE LAMP PARTY
Thanks also, yes I have 2 blue camping gas cylinder ones... I get them out and use them occationally.
I to miss that faint smell of Halide with it's pretty blue green and yellow flame. (don't look at the light!!)
Well I guess it's back to the Snoop then Guys?
Grizzlyhttp://www.refrigeration-engineer.co...ons/icon12.gif Seeking to join the BBT HLP.
I too have always recovered and recharged when using 404a. If you require a "critical" weight, then how do you know how much is left in the system. Also easier for F-Gas logs if over 3kg of course. I liked Halide when it went purple and flamed out.
Hi Grizzly:)Quote:
Originally Posted by Grizzly
I suppose I would site common sense.:D
The retrofit was carried out about 5 years ago.
R69L was only a drop in for R502, the system still had some R502 in it and R22 was less harmful (R69L is now not listed on the IDS web site).
R22 is still being made and correct me if I am wrong still available until 2010.
An old system is not best suited to the newer HFC refrigerants and as such will leak adding to global warming.
F Gas was brought in to control the HFC refrigerants which were adding to green house gases. R22 has no restrictions under F Gas.
Correct me if I am wrong in a case like this where the system was designed for R502 the best drop in may well be R22.
Is retrofitting R22 a crime even today:confused:I think not;)
In an old system I would not advise adding blends, what I would say is change the oil to ester in preparation for a furture retofit, but don't retrofit unless necessary;)
Kind Regards Andy:)
Pooh and Grizzly
I think you echo the sentiments of a lot of fridgies around the world. I certainly agree with what you have both said.
The replacement refrigerants for R12,R502 and R22 are more expensive, harder to leak check, need synthetic oils which are expensive and when there is a leak you have to reclaim and start again.
We don't know what long term effect these new refrigerants will have on the environment and it will probably be some time before we do.
R134A was supposed to be a long term replacement for R12 but there is some doubt about that now.
This whole debate about the effect on the environment has been discussed on other threads in this forum and no doubt it will continue.
I will get off Pooh's soap box now.
Paul
I found that on net. It is interesting.
Quote:
If a blend leaks out of the system, will I need to pull the remaining charge and recharge, or can I top-off the existing charge after repairs?
It depends. Studies were done a few years ago to show how higher glide blends behave during leakage and they showed significant fractionation, which affected the properties of the blend. When the system was topped off, the properties came back close to original. The cycle was repeated to see how many times the system could leak before topping off became a problem (the recommendation was not more than five). These studies were done on containers at rest, which promotes the worst case of fractionation.
Another study was performed recently on a system running full time, then cycling normally (2/3 on, 1/3 off), which found that the blend did not fractionate when the refrigerant is moving around inside, and not much fractionation occurred when cycling. Low-glide blends didn't show much fractionation in any case.
What this means is that running systems found to be low on charge have probably not fractionated the blend much, and can be repaired and recharged directly. If the system has been off for a long period (more than a day) and found to have leaked (worst case is about half the charge), it's probably better to pull what's left and charge with fresh, unless very little is gone, or very little is left. Low-glide blends won't cause any fractionation-related problems.
Hi Nike,
I wonder the source of that quotation ? it would be good if it was some official source.
Sounds like a document that was circulated by one of DuPont/ICI/Rhodia I cant recall exactly just around the time of HFC introduction. I am also trying to re-locate that document as it was very specific about the leak down & top-up rates plus the % capacity change ultimately after 5 such LIQUID LINE leaks - done for
407c and 404a I seem to recall.
Meanwhile here is something interesting from ARI on bulk tank refilling.
Just a little insight from an HFC manufacturer.
Years ago, when HFC's were first being used, we were concerned about fractionation. After years of field use and testing, we have determined that this is not a concerrn. This applies to all HFC, 400 series refrigerants. Remember, all 400 series refrigerants are zeotropes. You can top these systems off.
The greatest concern for fractionation is during charging. The refrigerant has to leave the bottle as a liquid.
HFC's will leak from a system if the elastomers (rubber material) are not replaced during the retrofit, from a chlorinated gas (R502) to a non chlorinated gas (R404A). This includes shaft seals. This is due to the chlorine causing the elastomers to swell at a different rate.
Not all HFC refrigerants require POE oil. Some are miscible with all oils.
Take care out there,
Dave
andy quick question am new to site not sure how it works
could you tell me or put me in the right direction as what the effect of 100 grams yes 100 grams of r404a refrigerant leaking into a well ventillated area would have on a person i think none but have a
complaint
dave the fridge
None at all!
Refrigerant R404a is gas with no smell, taste and it is non toxic. Only consideration is when large quantities escape in small area with no ventilation. Because it is heavier than air, in that case could cause suffocation because lack of oxygen.
Complaint could be if oil is smelled as part of refrigerant oil mixture, but it is harmless.