How to stop O2 from defrosting?

[augustinoi]

For me this is the hardest thing about the game by far. They did a good job with the cannon and the antenna update. So it ends up that making frozen O2 (and keeping it frozen is the hardest part.) I created this blueprint by searching the internet, but I can't cool the O2 to more than 185 C and it defrosts in the pipes even though they are made of insulating ceramic. insulator pipes would be nice, they are extremely difficult to get in quantity. If anyone knows how to return the liquid to the refrigerator or keep it at least 200C so the rocket can return. Plus, I haven't even done the hydrogen cooler yet.

[Charletrom]

If you extend your O2 line back to the reservoir and add a liquid vent you should be ok. Allow the pump to run continuously. This way you will never have liquid O2 sitting in the pipes.

[Primalflower]

Pipes ran through tiles will transfer heat faster than anything else due to the sheer mass of the tile. you may want to run them outside of the insulated tiles

[meekay]

I solve the problem by using mini pumps for my cryofuels so the packets are never more than 1kg each, so the game engine won't phase-transition them. They fill more slowly but the limiting factor for me is always cargo anyway.

And yes, as Charletrom points out, you should loop the lines back to the reservoir and add a detector to cut off the pump when your rocket modules are full.

[blakemw]

Options:

1. Recirculation, or if you have plenty of oxygen valving a small amount into space (or back into your base) to keep the pipe moving, valving like 50 g/s out the end might be enough to prevent pipe busting (in the long term after the system has mostly cooled down).
2. Run small thermal mass pipes (e.g. lead) through protected vacuum and prechill them with 1000 g/s Valving. This is a really good strategy and really should be used where practical. If the vacuum can't be protected (e.g. rocket exhaust) you might prefer to use Obsidian Insulated Pipe because its thermal mass is not that high
3. When pipe passes through a Bridge, it doesn't exchange heat on the Bridge tile itself, because it teleports across the gap. Furthermore, if the pipe is free-flowing rather than backed up it also barely exchanges heat in the input tile of the bridge. So bridge spam can reduce heat transfer in a backed up pipe by 33%, or in a free-flowing pipe by 66%.
4. Run Insulated Pipe through Insulated Tile but be careful, by far the best kind of Insulated Tile to use is Mafic followed by Sedimentary or Obsidian, this is because in the specific case of cell:building heat transfer when the cell is hotter a Ceramic Tile transfers 2.6x as much heat as a Mafic Tile or 1.3x as much as Obsidian (in contrast when the building is hotter, Ceramic is better), that it works this way makes no sense but ONI devs are weird. The best Insulated Pipe to use is either Obsidian if you want to minimize the time it takes to achieve thermal equilibrium, or Ceramic if you want to minimize heat transfer in the short term or in the very long term.
5. Take care not to run Insulated Pipe through high conductivity tiles, such as Bunker Doors or honestly pretty much anything which isn't Insulated Tile, Vacuum or "Bridge", Insulated Pipe likes to exchange heat with the cell it is in and doesn't insulate the contents terribly well (the reduction is only 1/32.5) so you definitely want a second layer of insulation.

Or you can do the hot loxygen exploit where you just Valve it to 1000 g/s and don't care how much it heats up, the Liquid Oxdizer tank will accept it at any temperature. This allows using normal pipes. You can also do some counterflow heat exchange trickery to heat up the Liquid Oxygen to "room temperature" right as it leaves the condensation setup while cooling the incoming oxygen to close to the condensation point, this allows for using normal pipes and getting Liquid Oxygen with very little cooling input because Counterflow is doing most the work.

[Gurgel]

You need to loop it and empty the pipes. Simply place an element sensor at the pipe end behind the rocket tank and stop pumping when the tanks are full and it starts coming back. 

[Alex_D]

(I haven't played in a while, so my advice might be out of date)
I use the 1/10 mass trick, or mini-pump in this case. I also use an array of pipe meters to deliver the exact amount of liquid O2 and H2 to the rockets.