The secret to freezing samples in liquid nitrogen storage tanks is “liquid nitrogen”.

The vacuum structure of the container keeps the liquid nitrogen out of contact with room temperature and then uses insulation materials to reduce the natural loss of liquid nitrogen.

Extended liquid nitrogen preservation times of 50, 100 or more days.

How often do I need to refill the 30-liter liquid nitrogen storage tank that is more commonly used for freezing this sample?

You have to look at the container caliber before deciding!

Similar to water cups, the same amount of hot water is always cooler with larger cups.

The same is true for 30-litre liquid nitrogen storage tanks, where the larger the calibre the shorter the preservation time of the liquid nitrogen.

The following is the liquid nitrogen tank manufacturers to organize the preservation time.

30-litre 125mm calibre liquid nitrogen tank with a static liquid nitrogen shelf life of 85 days.

30 liters of 210 mm with 45 days static liquid nitrogen storage time.

The difference in preservation time between large and small calibers is nearly half!

So, if it is a 30-liter 125mm liquid nitrogen storage tank, when it is filled with liquid nitrogen and not opened for use, it will take about 80 days to add liquid nitrogen once; for a 30-liter 210mm, it will take about 40 days to add liquid nitrogen once!

Also note that static save time ≠ use time!

Liquid nitrogen storage tanks used frequently with the lid open will take less time to add liquid nitrogen, the specific data need to be determined according to the use of the situation, the more frequently used to add liquid nitrogen time will be shorter.

A more prudent way is to fill up with liquid nitrogen and use it once and record it to determine your dynamic retention time.