purging non-condensable gas from a storage cylinder
 

I found this information in a pdf www.robinair.com/sites/default/files/25175B.pdf
On page 7. It's also in the manual for my new RG3. (No pdf).

Anyways, I wonder how much this decontaminates R410a that has some air mixed in??

It works for purging the lineset for refrigerant gauges.

I guess it all depends on your standards of purity. The more air and the lower the tank level, the more headspace gas you will need to pull to remove the air. If the gas is stratified well, most of the air will come out first. Yadda yadda. Better than wasting the whole tank IMO.

The other factor to consider is this: the volume of R-410a that is outgassed to remove air will contain the lightest fraction of the mixture. In effect, you will be distilling out a fraction of the mixture, which could throw off the properties. Just as in distilling moonshine, the heads come out first. In this case, any lost booze is bad. You can use it, but it will not be the perfect blend.

Thanks for the reply. I've been thinking about the process of pulling out the charge,
checking it's weight, and then using it to recharge the system..
But, maybe it would be safer to use brand new R410A..?.

I guess the main point of bleeding off the non-condensable gas, is to keep the pressure 'normal'.
So you can keep using the recovery tank without fighting with it's pressure..

I saw this 'guide' to preparing a new tank. Getting rid of all that nasty nitrogen, before use..
https://youtu.be/E6-DDjWvHHU

A method of getting rid of air in a recovery tank is pump the liquid off the bottom
of the tank, into another tank.. https://youtu.be/pDxRnEqSFyE
Too bad, I only own one recovery tank..

I have seen refrigerant purge systems on R11 centrifugal chillers . In operation , the were running less than 1 atmosphere suction pressure and some what above 1 atmosphere on the high pressure side .

So , the plant operator was more concerned with air ( and water vapor ) being sucked in with a leak on the low side ( raises head pressure + the problems associated with water vapor ) . Than a leak on the high side loosing refrigerant .

The purge unit ran continuously ( small electric motor ) , pulling air + refrigerant gas from the top of the chiller vessel . The compressed mixture was run through a condenser coil , then into a small vessel . Liquid refrigerant would collect in the bottom of this vessel & the non condensables remain above the condensed refrigerant .

The vessel had a float & when liquid refrigerant reached a certain level , it would be discharged back into into the main chiller vessel .

The non condensables would be " burped off " periodically , maybe responding to pressure ? In theory , this would be mostly air and water vapor ?

God bless
Wir

That's what empty propane bottles are for....:D

Right side up, gas comes out. Upside down, liquid comes out. Hmmmmm...