====== Warming up the entire cryostat to room temperature ======

That's rather simple: just stop filling the helium tank and the nitrogen tank. The system will warm up by itself in about 3 days. You can follow the warming up by checking the two thermometers (VTI-bottom and λ-plate, T1 and T2). 7Ω is nitrogen temperature, 19Ω about 150K, 28Ω is 300K.

In any case there are some //very important// measures to be taken while warming up, to avoid explosions of tubes or capillaries due to the expansion of gases (Helium, Nitrogen and air) when warming up from low T to room T. //Never forget these steps before warming up//, or cryostat damage can be a consequence.

  - Close the needle valves.
  - Connect He-tank to recovery (should be already like that).
  - Connect VTI to recovery.
  - Conenct λ-plate pumping line to recovery.
  - Put an overpressure release after the speedy valve of the vacuum interspace. When the cryostat is still a bit cold (~19Ω or less), open the speedy valve. The underpressure will keep the space sealed automatically, but if there builds up overpressure, the overpressure release will go off.


Warnings and advises: 

  - NEVER NEVER NEVER vent the superinsulation, neither to air nor to Helium, nor to nothing.
  - If you do not want to keep the cryostat warm for long, it's convenient to keep a Helium vessel connected to the recovery close to the cryostat, so that the boiloff will keep the cryostat "conditioned" at Helium athmosphere.
  - If you want to keep the cryostat warm for a long time, avoid to vent any space to air.