When charging blended refrigerants we always do so as a liquid to prevent fractionation, great. So what happens when the bottle is close to empty and only contains vapor? I've often sucked what's left in a r410a bottle into a system that's under vacuum before opening the service valves. With the introduction of r454b and a larger glide, I'm concerned about doing this. Once the bottle contains just vapor, is it fair to say it's no longer the correct mixture of refrigerants?
Charging as a liquid, what happens when only vapor remains in the bottle?
bbuller
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When charging blended refrigerants we always do so as a liquid to prevent fractionation, great. So what happens when the bottle is close to empty and only contains vapor? I've often sucked what's left in a r410a bottle into a system that's under vacuum before opening the service valves. With the introduction of r454b and a larger glide, I'm concerned about doing this. Once the bottle contains just vapor, is it fair to say it's no longer the correct mixture of refrigerants?
I suppose that's the root of my question, if the refrigerants are boiling off at different temp/pressure wouldn't the ratio in the vapor be off?
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Pull the remaining vapor and I’ll bet it’s not even 1 oz!
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50,203 Posts
You're removing it as a liquid so no boiling is going on
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Incorrect.
Reputable refrigerant manufacturers pull their tanks into a vacuum before filling them. If they didn't the refrigerant would immediately be contaminated with air and moisture.
This is why you should avoid ordering refrigerant from shady online sites or from countries like China. They have fewer or no quality standards and have been known to fill tanks with whatever gas they have laying around. Remember when they were selling straight propane as an R22 drop in?
I don't know about everyone, but our recovery cylinders go to a recycler. The recycler empties them, re-tests them, puts a new cylinder valve on, paints them, and pulls them into a vacuum before sending them back.
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I think the packager that I saw was trying to justify his own careless method of filling. He is in the small 1 - 3 pound containers of R600A and R290. (Something like that). Thanks for the clarification and the warning. Think twice before you suck out the last few ounces into a system.
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I have had that question ever since blended refrigerants were available. Everyone in chemical engineering that I have ever spoken to seemed surprised by the question. Although The Answer seems obvious to me.
If the refrigerants vaporize at various temperatures - at a constant temperature the highest boiling point refrigerants would be predominate in the vapor. A conclusion which seems to be echoed in the original mandate that system using blended refrigerants could not have the refrigerant charge be substantially topped up without performance being impaired due to mis-proportioned refrigerant.
That being said; if the above is true then the opposite is also true - the liquid refrigerant being removed from a cylinder must ever increasingly be the lowest boiling point refrigerant in the blend.
But having never received a genuine answer beyond my own logics - I have concluded that the refrigerant makers either manipulate the blend to compensate for the cylinder removal distortions in the blend - or none of means anything worthwhile in a practical sense.
I always prefer a sharp pencil - but so long as the dull one makes a mark sufficiently well; I guess there is no real need to go sharpen it. <g>
Calculus incorporates has chaos theory - we have de minimus theory. <g>
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We’ve encountered this exact scenario often, especially with R410A and now R454B, as it becomes more common. Based on our field experience, once a cylinder contains only vapor, the risk of fractionation becomes a significant concern, especially with high glide blends like R454B. That’s why our techs are trained to stop charging once we’re out of liquid, even under vacuum, to preserve blend integrity and avoid performance issues down the line. Better safe than calling back!
Stay sharp out there.
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Stay sharp out there.
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This is a good topic.
One thing we need to introduce is the volume.
11.2lbs system versus a 112lbs system the fractionation will be less noticeable in the larger system, over average conditions.
Just like a loss of a charge of 10lb charge of the old R22 systems of large volumes, was not noticeable, till a detailed analysis was done.
As pecmsg state not enough to worry about.
Just like what's in your charging hoses. Now do we need a hose for every flavor out there.
Labeled: (the refrigerant of choice)
R=reclaimed
RA=Reclaimed with acid.
VG=Virgin Gas state.
VL=Virgin liquid state.
All joking aside. Fractionation exists just remember the volume that you're working with. 30Lb cylinder 90lb cylinder 250lb? at least the gas is contained, for proper disposal.
One thing we need to introduce is the volume.
11.2lbs system versus a 112lbs system the fractionation will be less noticeable in the larger system, over average conditions.
Just like a loss of a charge of 10lb charge of the old R22 systems of large volumes, was not noticeable, till a detailed analysis was done.
As pecmsg state not enough to worry about.
Just like what's in your charging hoses. Now do we need a hose for every flavor out there.
Labeled: (the refrigerant of choice)
R=reclaimed
RA=Reclaimed with acid.
VG=Virgin Gas state.
VL=Virgin liquid state.
All joking aside. Fractionation exists just remember the volume that you're working with. 30Lb cylinder 90lb cylinder 250lb? at least the gas is contained, for proper disposal.
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50,203 Posts
Half a degree. Oh boy !
There's so many variables that could make half a degree difference it's not even worth mentioning.
nationalref.com
There's so many variables that could make half a degree difference it's not even worth mentioning.
R410A - National Refrigerants Ltd
GWP: 2,088 IPCC 4th Revision Application: A/C Preferred Oil: POE Ashrae Class: A1 Composition: 50% R32, 50% R125 Available Cylinder Sizes 9/20/46 Kg Cyl - 720 Kg Drum, ISO Tank
nationalref.com
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OK; the remaining vapor in the cylinder - after the liquid is gone - is disproportionately the highest boiling point refrigerant in the original blend.
So what does that mean?
Well; for one thing; it means that the liquid removed from the cylinder as it was charged into a system is now disproportionately the lowest boiling point refrigerant system in the original blend.
Which is a far more important consideration as the system is actually using that altered blend - at least the disproportionate vapor remains harmlessly in the cylinder.
Keeping the tanks cool to keep the Vapor phase pressure above the liquid is another factor to be considered. The volume of the tank/system ratio still needs to be considered.
off topic but still related:
No more hot water quenching of the tanks or heat blankets
The design of the piping system must include charging ports to assist in liquid charging. with low pressure state tanks. I see many manufactures doing this in the industrial side.
I don't work on Resi so That I am speculating that it is being considered?
off topic but still related:
No more hot water quenching of the tanks or heat blankets
The design of the piping system must include charging ports to assist in liquid charging. with low pressure state tanks. I see many manufactures doing this in the industrial side.
I don't work on Resi so That I am speculating that it is being considered?
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353 Posts
So what separates the nitrogen from the content of the tank whether it be gas or liquid ?
And are we sure the nitro is a vapor on the bottom of the tank ? What if it is a vapor at the top ?
things that make yah go huummmm.
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50,201 Posts
When you're done charging liquid into the system, there's about one pound of vapor left in the tank. Once in a while you NEED that one pound to put in the system. I've never had a problem taking every last bit out of the tank that I could. Maybe that will change with 454, I don't have a clue, but I'll bet after 5 pm on a Friday it will be just fine.
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