The large air separation units contain devices for the extraction of rare gases. Realized in them processes are carried out at the temperatures from 30 to 120 K. For the cryogenic providing these processes use liquid nitrogen. The features of two supply chains cryogenic equipment liquid nitrogen are considered. The first of them is basic, with a continuous flow of nitrogen through the pipeline, and the second contains additional capacity, which is installed close to the user. The advantages of the second scheme of the periodic supply of liquid nitrogen in the additional capacity are substantiated. A relatively simple method determining the degree using cold nitrogen vapors formed by cooling cryogenic piping with thermal insulation was proposed.