Can i have information on Triple Evacuation?
Procedure, etc
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Can i have information on Triple Evacuation?
Procedure, etc
Hi, kpapa :)
Welcome to RE,
try this or google for more;)
http://www.mitsubishielectric.ca/hva...stallation.pdf
http://www.bdt.co.nz/comfortmaster/d...410a_guide.pdf
http://www.achrnews.com/CDA/ArticleI...102323,00.html
http://www.supplyht.com/CDA/Archives...00f932a8c0____
http://www.xpedio.carrier.com/idc/gr.../24apa-3si.pdf
http://www.hvac-talk.com/vbb/showthr...postid=1181809
http://www.uaf.edu/fs/design_spec/15600_1.pdf
Hope this will help :)
Best regards, Josip :)
Hi Josip,
I like the Carrier installation sheet you provided the link for. On page 6 it shows a very good chart for deep vacuum purposes.
Very nice.
Hi, US Iceman :)
yes it is ok, but I'm using an old procedure given by STAL Sweden for large cooling plants. It is not possible to upload (scans) because it is bigger than 100kb.
There is nothing new in that procedure but for sure you must have a good vacuum pump, good connection to the system and must be very patient. Of course you must know what are you doing ;)
Best regards, Josip :)
Now that takes all of the fun out it.:DQuote:
Originally Posted by Josip
I would like to see the Stal information if you could email it to me.
Thanks in advance Josip.
Best Regards,
US Iceman
Hi, US Iceman :)
check your email, please ;)
Best regards, Josip :)
Finally some sense in an instruction. One good vacuum is all you need. The triple evacuation is a left-over from the days of using low-side gauges (inches of mercury) and inadequate vacuum pumps. If you can achieve and maintain a 500 micron vacuum once, you don't need to attempt it 2 more times.Quote:
Deep Vacuum Method
The deep vacuum method requires a vacuum pump capable of
pulling a vacuum of 500 microns and a vacuum gage capable of
accurately measuring this vacuum depth. The deep vacuum
method is the most positive way of assuring a system is free of air
and liquid water. (See Fig. 6)
Dan,
The best part of those instructions... They are almost 40 years old.
I have to agree with you on the triple evacuation method. If a good vacuum can't be done right the first time, why go back and do it two more times?
Is that supposed to improve the odds of getting a dry system?:D
I've used the triple vac system several times.. However those are due to the lovely drying technix of some manufactors. Other wise vaccum would take a couple of days.
99% of the time mine go down to 250microns or less.
-120F is mighty cold.
One thing which has always bugged me. Is how people preform a vaccum test. Most who use a micron gauge just hook it up to the vaccum pump. The best way to get a true system reading is at the TXV.
Quote:
Originally Posted by Dan
Absolutely.
At the risk of opening a can of worms?..
Triple evacuation serves no purpose whatsoever these days, other than to waste time. You cannot legally do it with refrigerant and what?s the point of filling with Nitrogen three times and letting it go?
You can do the job better and faster if you are properly equipped with a good quality vacuum pump and efficient evacuation path without valves and other obstructions plus, of course, a gas-tight system.
Really, triple evacuation is a relic of the old days when you used a triple flush of refrigerant to get non-condensable gases out.
Here?s a thought about triple evacuation that was explained to me many years ago when R12 was free and nobody cared how much was used and how much disappeared into the atmosphere.
It works like this.......
If you have a system that contains air or non-condensable and you release the lot (as was commonly the case in those days) and no vacuum pump (as was also common), when you reach atmospheric pressure in the system you still have a system full of whatever is in it (air etc) at 1 bar or 14.7 psi. It is this heel of non-cons that has to come out.
It was the removal of this lot that triple evacuation was used for.
You now pressurise the system with, for argument, 10 times the volume. You now have a ratio of 10:1 air / gas. Release it all and repeat the exercise. The remaining ratio is now 100:1, do it a third time and your ratio of mixture is 1000:1. This was considered safe enough to add a working charge.
I should point out that this method of venting refrigerant is now illegal, but that is the origin of the triple evacuation method.
It simply removed most of the non-cons by progressive dilution.
If all that you need to do is to remove non-cons from the systems, a good quality vacuum pump producing a deep vacuum does a better job every time.
Moisture removal is an entirely different kettle of fish.
.
________
Yamaha MO specifications
First off my practical experience of refrigeration is limited, but I have used vacuum ovens a lot. These always had a nitrogen bleed at the opposite end of the chamber to the vacuum connection, say 20ml/min in an oven of about a cubic metre. Without this, solvents with higher boiling points (60-80C) would not leave the oven, they'd evaporate off the stuff you were drying (oven set at 40C) and pool in the bottom. A small gas bleed carried away the solvent vapour to the vac pump, prevented the oven being a dead end. I've no doubt Argus is right (and you others), but I would have though that filling a system with nitrogen and sucking it back out will better help shift moisture. But then maybe you only need to do it once after all?
Don't we have some delightful sayings in the English language :)Quote:
Originally Posted by Argus
Any others come to mind?
P.S. I fully agree about the triple vac. As Iceman said, if you can't do it right first time ...........
Yes we do. It is always fascinating to hear these and try to learn where they come from. The one that comes to mind right now is; "I wouldn't touch that with a 10 foot pole".Quote:
Originally Posted by frank
This came from the middle ages during the plague!
or, "don't look a gift horse in the mouth" (I still have problems understanding that one)
or, "throwing the baby out with the bath water".
or, some others that use too "colorful language".
This would make a good subject for a darn good book. It shows how the language developed. The funny thing is, how do these keep getting passed around?;)
Frank, this would be a good thread to start in the chit-chat section don't you think?
Yes I do :) Me or you?Quote:
Originally Posted by US Iceman
Agreed, if it vacs the first time why do it twice more?
some people do, some don't.
thats the way the mop flops.:)
I would like to thank all of you. i will try my best with this triple evacuation.
maybe we should move this to the new thread in ChitChat & Service Stories :D - another English saying, although I can't say I've used this one in the pastQuote:
Originally Posted by slingblade
So you use triple vac for moisture removal???? (please explain this different kettle of fish)
I am at college at the mo and they worship triple vac and say that the dry N2o removes moisture?
Bear in mind that the use of OFN will absorb free moisture within the system.
The use of OFN will also minimise any change in recorded pressure due to deviation in ambient temperature on a pressure rise test.
Hi,
I'm afraid this is not exact:confused: I think this kind of chemistry or physics cannot work.Quote:
Originally Posted by mxstar
Main reason to use OFN instead of AIR for pressure test is to not charge the system with additional quantity of moisture and oxygen.
Best regards, Josip :)
Josip
Could I get the Stahl informationt to please
Thanks
Hi, nh3wizard :)
of course :) PM your email address, please;)Quote:
Originally Posted by nh3wizard
Best regards, Josip :)
Josip,
I agree about the main reason for the use of OFN as opposed to air. Typically specification for industrial air will be less than 250ppm moisture and less than 8 ppm for OFN.
Regarding pressure rise test have a think about ideal gas laws pV=mRT, considering the individual gas constant for air vs nitrogen. Also F1 teams fill their tyres with N2 as opposed to air for a number of reasons one of which is less deviation in tyre pressure which change in tyre temperature when filled with N2 as opposed to air and tyre pressure is particularly important when it comes to adhesion and performance.
Josip
Could I get the Stahl informationt to please
Thanks
OFN has a marvelous affinity for moisture !(not air) It will absorb as much moisture as it can to saturation! Progressively lower pressures allow for complete moisture evaporation from the system and then allow it to be absorbed by the nitrogen! Standard safe environmental practice in the event of a suction leak or opened system! DO NOT USE REFRIGERANT IN THIS PROCEEDURE! It is completely wrong and against the law! Leave it to the countries that don’t give monkeys about the environment to do it with refrigerant!
When triple evacuating it is useful to break the vacuum into the discharge service port. This pushes contaminants through the system into the low side. Then start the next evacuation at the suction service port, pulling contaminants first.
Oil absorbs refrigerant. That's why an initial evacuation takes a long time, because the refrigerant is very slow to escape from the oil.
OFN is not absorbed into the oil, so a second and third evacuation can be done very quickly when breaking the vacuum with OFN.
In my opinion, a triple evac with a mediocre pump is better than an all-nighter with the best pump in the world.
2 year old necrothread not as bad as a 6 year old one I saw once!
For small units with sever contamination I bleed OFN in at the discharge port while vac'ing and put a box over the plant with a blow drier to heat it all up! Of course remove the oil or it takes a loooong time to get that stuff boiled out ;) !
A new filter drier will pull the moisture out of the POE very quickly (usually less than an hour of operation).Quote:
Originally Posted by The MG Pony
Vacuum will pull the moisture out of the POE, but it will take days if not weeks of constant vacuum and breaking with dry nitrogen cycles. It's much quicker and easier to remove the moisture with a new filter drier.
:off topic:
With regards to the torr gauge at least put it on the liquid line service port, so you know the vac is being pulled throughout. And I make you right NIKE, Fit a new filter drier,Perform a proper vac,gas it up,run it, change the drier again, Happy Days!
Hence why one must remove the oil! The slight bleed of ofn really speeds up the drying of the system with out having to change vac oil :)Quote:
Originally Posted by nike123
Come on guys, the tripple evacuation method is used after a severe burn out. It's used to flush out any non condensables like acid, water and oil, not just moisture. You have a burn out, you flush with Rx11 flush, then nitrogen, then another nitrogen flush, then a deep vacume. Time consuming, but it keeps you from having to changing out the compressor more than once. Ever heard the horror stories about multiple comp failure? No triple evacuation is usually the cause.Quote:
Originally Posted by US Iceman
If you don't change the vac oil, water and non condensables mix with it after a while, this breaks down the oil, and WILL KILL YOUR VAC PUMP, trust me, I've f'ed up plenty of things while perfecting my craft over the years.;)Quote:
Originally Posted by The MG Pony