nismoxr34
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No oil leaked out, just had a refrigerant leak. Could have evacuated that but no need.
A/C O-Ring Sizes
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No oil leaked out, just had a refrigerant leak. Could have evacuated that but no need.
nismoxr34
New member
No need to go through the trouble of using the Parker catalog. Mobile HVAC O-rings are pretty standard. Any auto parts store should be able to match up your o-ring and get you a new one cheap. You can buy a whole generic set for $10.
28inHg isn't enough to boil off the water remaining in the system that has been exposed to atmosphere. Water boils at ~100 deg F @28inHg. You mentioned using a micron gauge, so maybe you went well below this. My gauge only reads up to 12,000 microns (~29.4inHg).
The two main reasons to evacuate the system are to remove the air, since it hurts the refrigeration process, and to remove water. Excess water can be absorbed by the desiccant. However, PAG oil is extremely hygroscopic and can suck up moisture and lead to oil breakdown.
So True! Sorry I forgot to clarify. I don't quite remember what the gauge was reading, but I know for sure I was pulling ~30 inHg. Thanks for clarifying and I'll fix that up front.
I was reading around 650 microns, so reducing the atmospheric pressure to match vapor pressure! 6 degrees to boil off the water. I made sure that the micron gauge didn't creep, ensuring there wasn't anymore water in the system absorbed into the oil and desiccant. I made sure to keep the system as closed as possible, and the change out the refrigerant as soon as possible to minimize the water absorption into the system. Didn't have to pump down for much time so that kind of proved it for me.
Thanks for clarifying that, and hope I didn't confuse anyone else.
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nismoxr34
New member
[MENTION=66389]BlackWorksInc[/MENTION] [MENTION=90026]JeremyB[/MENTION] [MENTION=66316]1engineer[/MENTION] I love these handbooks, they make it way too easy for us nowadays with the internet. I'm so used to steam tables, chemical compatibilities etc. from working in a lab and being a chemical engineer.
Thanks for all the help [MENTION=66316]1engineer[/MENTION] I need to participate more in these type of discussions. When I installed the lift with a buddy, he was just torquing the nuts in and was like... that's good. But the engineer in me needed everything torqued to spec of course.
Thanks for all the help [MENTION=66316]1engineer[/MENTION] I need to participate more in these type of discussions. When I installed the lift with a buddy, he was just torquing the nuts in and was like... that's good. But the engineer in me needed everything torqued to spec of course.
1engineer
Moderator
It's mostly right though haha. Geez man the first time I had to hand calculate thread shear (before apps) I had parts of the handbook memorized!
My favorite of all time is the 1960-1961 (42nd edition) Practical Handbook of Chemistry and Physics. It is sitting on my shelf above me as I type. Sure, the Machinery's Handbook will tell you how to build stuff but... can it help you use spider web to make a gun scope? Coefficient of friction of steel on steel lubricated with animal sperm? Benzene? Oleic acid? Laboratory Arts and Recipes? Food preservation? Recipe for mirror silver? From base elements? How to make conducting wire? Again from base elements? And finally! Mathematical formulas for just about everything and tables! Steam, resistance, specific gravity and pretty much all of them. This little jewel has 3,481 pages and combined with the Machinery's Handbook will let you figure out and do just about everything in the world.
Last but not least is the 'ol Steel Construction Manual. Any beam, any load any time. These three books are pretty much all you need. Unfortunately you need to be smart enough to use them lol. I struggle mightily with some of the chemistry and if you don't use some of the higher mathematical equations regularly then you lose that ability unless you re-learn.
1engineer
Moderator
No problem! There are some sharp guys here but there are some who think bluster and pontification will get the job done. They need to go work in a lab or an engineering group for just one day.
Lester Lugnut
New member
Refrigerant mixes with the oil.
nismoxr34
New member
Yes I know, but the same thing happens when you evacuate the system and remove water/air. Oil isn't the same hydrocarbon compound as the refrigerant. (oils are usually very long, hydrophobic hydrocarbons which do not turn into gaseous form unless burned) The refrigerant is a compressible liquid which has some pretty interesting thermal properties. If compressed (above the vapor pressure), we have it in liquid form (high pressure side), but when put through the expansion valve it vaporizes and turns into a gas. All the energy required for phase change (enthalpy of vaporization) is an endothermic reaction, causing the low pressure side to cool.
So if I look at the MSDS of R134a
http://www.refrigerants.com/msds/r134a.pdf
we see its a fluorinated hydrocarbon (1,1,1,2-Tetrafluoroethane)
I see that the boiling point is -26.2°C (-15.1°F) and vapor pressure is 85.8 psia @ 70°F
This tells me that at room temperature there ideally should be all refrigerant vaporized. But if the system is under some sort of pressure, we could be effectively raising the atmospheric pressure above the vapor pressure, allowing for liquid refrigerant. This is why we can pull vacuum on the line to vaporize all refrigerant and if the micron gauge doesn't creep up, we know there should be no more contaminants in the system.
Lexusbstrdchild
New member
Hey it's ok to be a Lamda!
