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Hi, I'm a fridge engineer who has recently taken over the maintenance and service of a supermarket with a new Co2 system. I have been told to ensure that the system never goes below 5bar during operation/maintenance because of the danger of forming 'dry ice'.
My question is, if this does happen will repreasurising the system 'melt' the dry ice? if not what do we do to ensure the dry ice is out of the system before we continue?
Any advise would be great as this is the first time I have delt with Co2.
Cheers Rowan
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Hi Rowan,
Are you talking about the pressure in action or refilling ?
For the active cooling there is generally no danger because the evaporating pressure
is much above 5 bars, even for freezers.
For commercial refrigeration you only have to take care that while refilling CO2
(in the case of leakage) the filling pressure is not around 5 bars or lower if you fill liquid. If the system is under 5,3 bars because of leakage, you have to fill gas until you
reach more than 5,3 bars, then you can refill liquid CAREFULLY.
Greetings, Matthias
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Rowan,
Now I don't know what system you are looking at but I would assume that the system is protected with a pressure switch to cut out if the pressure becomes to low. The 5,2 bars are absolute pressure which means that you manometer will read 4,2 bar.
It really depends on the system design how you charge the system but the cylinders you often use in supermarket systems have a pressure of about 55 bars at 20C out door temperature so you can easily charge the liquid where you want unless you are running transcritical.
Greetings Alex
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Rowan,
You are more than welcom to contact me with regards to this installation as I think I suspect which one you are talking about. Don't worry about the Dry Ice issue. Unless you have a major issue like a catastrofic leak you should never encounter this situiation. Bringing the pressure back up above said pressure (5 bar approx) will melt the dry ice and once up to my recommended pressure of between 8 and 10 bar you can safley charge with liquid Co2 remebering always to keep an eye on pressures both in the receiver, dischage and suction.
Any problems contact me 24/7
Regards
Martin R
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RE: commisioning of cascade sytems
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Hi;
I am a student in Univercity for MS degree and I am working on CO2, I designed a cascade system with CO2 and R-404A for the test.
Do you suggest any thing to me before charge the CO2 to the system for security during the filling? Or is there any installation manual for commisioning and charge the CO2 to sytem?
Thank in advance for your replies.
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RE: RE: commisioning of cascade sytems
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Mrs. Ayse Karaoz posted on 2008-12-02 20:53:37: Hi;
I am a student in Univercity for MS degree and I am working on CO2, I designed a cascade system with CO2 and R-404A for the test.
Do you su ... Jump to Post Hi Avse
If you tell me what temp range you are operating at I can advise on some of your questions
if you are still stuck
Andy
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RE: RE: Co2 below five bar
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Anonymous posted on 2008-08-07 20:21:46: Hi Rowan,
Are you talking about the pressure in action or refilling ?
For the active cooling there is generally no danger because the evaporating pr ... Jump to Post The only thing you should be wary about operating at that pressure is getting any in the comp.
If it is a supermarket application you should only be running the system at about 11Bar -35c aprox there is no major issues with charging the system at that pressure just do not go into the comp as you would on a normal with vapor
Andy
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