For the first time the frozen goods is into the container within 2 ~ 3 hours, after suggest user to carry out the personnel, observe whether external surface of the container is condensed water or regularly frost phenomenon, such as appear in both cases, show that container vacuum has been deteriorating, will cause the container of liquid nitrogen in a very short period of time volatile, container can't normal use. Although the probability of this phenomenon is very small, may be due to the product requirements for loading and unloading, transportation, but in order to avoid the loss of frozen items, this observation is necessary.