Carbon dioxide is like nitrogen in many ways, but if it is mixed with limewater, it causes the clear liquid to because milky, while nitrogen dose not. This is the test for carbon dioxide.

If oxygen-deficient atmospheres are suspected or can occur, use oxygen monitoring equipment to test for oxygen-deficient atmospheres. Review the liquid nitrogen Material Safety Data Sheet (MSDS).

It has been proved by test that the problem of large space simulator liquid nitrogen system starting has been solved successfully in simulator liquid nitrogen system.