For new container or a container thawed and reheated, a small amount of liquid nitrogen must be filled into before use .When filling liquid nitrogen, pump or long tube funnel should be used. The filling pipe should be inserted near the bottom of the container, and leave a gap at the mouth of the container to let nitrogen escape. The height of the liquid nitrogen level in the injection container shall not exceed the plane of the lower end of the neck tube. Avoid contact with liquid nitrogen during operation to avoid frostbite.