The battle against Condensation
There is a problem when you cool you hardware component below zero degrees, there is one enemy you have to look out for and that's condensation. Condensation occurs when the temperature of air is below the dew point. This means that the water within the air returns to its original liquid state. Condensation does not happen at one particular temperature but happens by a difference of two temperatures. Because of the extreme cooling we are using the surrounding air is also cooling down.
When we are cooling with extremely low temperatures the water, after reaching the dew point, immediately starts to freeze and becomes ice. That's the reason why you see so very often, during a LN² session, ice on the outside of the tube etc. You probably can imagine that if you do nothing during a LN² session, some or all of your hardware will die as water will short something out.
Ice on the outside of the tube after about 2,5 hours of benching
What can be done to prevent the hardware from dying during a LN² session? The answer is simple.
You have to isolate the hardware from the condensation. When you isolate the hardware, you prevent the condensation (water) from getting to the electronics of you hardware. For this I always use the following:
- Eraser gum, for the insulation of the main board
- Armaflex, for the insulation of the tube and partly of the mainboard
- A paper towel for absorbing the condensation during the LN² session
In the following photo you will see how to insulate a main board.
Main board isolated with erasable gum