First, take out the liquid nitrogen tank and liquid nitrogen, leave it for 2-3 days, wait for the temperature in the tank to rise to about 0 °C, and then pour warm water at about 30 °C and scrub with a cloth. If you find that individual melted substances stick to the bottom of the inner tank, be sure to wash them carefully. Then rinse with clean water several times, and then invert the liquid nitrogen tank, put it in a safe place indoors, and dry it naturally, or air dry it with a blower. Note that during the whole brushing process, the action should be gentle, the temperature of pouring water should not exceed 40 ° C, and the total weight should not exceed 2kg.