That’s interesting. May I ask you a few questions?
Why are you storing in the gas phase?
Some temperature spiking is normal, but it should not exceed the glass transition temperature of about -130°C.
Glass transition of what, the samples? Sample containers? …?
“one-fill all-fill” (OFAF) to work. OFAF fills all tanks sequentially once any one triggers the process.
What are the benefits of that?
From the usage graphs, why does it seem like Tank 1 is using the most nitrogen, even though Tank 3 is getting accessed the most? Shouldn’t Tank 3 have higher losses?
When freezing samples, they are cooled rapidly to form vitreous (noncrystalline) ice. If the ice warms enough (and that temp is still well below 0°C), it can transition into a crystalline form. This makes the ice expand and become spiky, which can damage proteins and cells.
For differences in LN2 usage, not every dewar is created equal. Age, the degree of vacuum between the walls, and the distance between the inner and outer walls can substantially affect the thermal conductivity, and thus the boil-off. Differences in how they are capped (which by nature can’t be vacuum-insulated) can also change their efficiency.
That’s interesting. May I ask you a few questions?
Why are you storing in the gas phase?
Glass transition of what, the samples? Sample containers? …?
What are the benefits of that?
From the usage graphs, why does it seem like Tank 1 is using the most nitrogen, even though Tank 3 is getting accessed the most? Shouldn’t Tank 3 have higher losses?
I can answer questions 2 and (tentatively) 4!
When freezing samples, they are cooled rapidly to form vitreous (noncrystalline) ice. If the ice warms enough (and that temp is still well below 0°C), it can transition into a crystalline form. This makes the ice expand and become spiky, which can damage proteins and cells.
For differences in LN2 usage, not every dewar is created equal. Age, the degree of vacuum between the walls, and the distance between the inner and outer walls can substantially affect the thermal conductivity, and thus the boil-off. Differences in how they are capped (which by nature can’t be vacuum-insulated) can also change their efficiency.