Liquid level is a simple measurement tool, liquid nitrogen biological containers filled with liquid nitrogen and use for some time, how much liquid nitrogen in the container rest is the user eager to understand. Therefore, We produced this simple ruler. Ruler with a cylindrical structure is solid, the surface spray black low temperature paint. When measuring, insert the bottom of the level gauge straight into the bottom of the container. At this point, take the ruler of the hand, the ruler into the boiling water feeling. Keep 5 to 10 seconds, the feeling of liquid nitrogen no longer boiling, can only come up with. At this time, it can be observed that the liquid level in the liquid nitrogen soaking parts will occur frost. White frost and black paint to form a huge contrast, you can intuitively clear understanding of the container in the remaining liquid nitrogen stock.