As the distance from the tank to the point of use increases, the initial piping cost increases, and potential for heat leak becomes even more critical. Application Cycle Time. Cycle time, or the frequency at which liquid must be supplied at the use points, plays an important role in the efficiency of any cryogenic system. When a cryogenic liquid first is introduced into a warm piping system, the liquid vaporizes and creates gas. This process of cooling the pipe until it is full of liquid can take from 10 min to 1 hr, depending on the size and length of the piping and the rate at which gas is vented away.
Gas vented from the piping is an unrecoverable loss.
When the pipe is left unused for a period of time, the piping will warm up at a rate equal to the heat leak rate. The higher the piping's heat leak rate, the faster it will warm up and the more liquid will be required to recool it. This is defined as the ratio of liquid to gas supplied at the use point. The higher the percentage of liquid, the higher the liquid quality. High liquid quality is important for smooth fluid flow through the piping system and proper equipment operation.