Understanding the basic properties of liquid nitrogen and the fundamentals of cryogenic pipe design can help plant engineers specify distribution systems that comply with safety protocols, meet user expectations and maximize efficiency.

During extended periods of nonuse, the liquid nitrogen inside a pipeline eventually will warm and turn into gas, and this gas will “push back” to the bulk tank. Using an inline venting device will keep the line wetted with liquid nitrogen.

Provide the answers to these nine questions about your cryogenic application to any supplier from which you are requesting a quote. Thoroughly considering your application before contacting the supplier can help you understand your needs and how a supplier can best satisfy them.
  1. What is the application?
  2. What is the pressure requirement for liquid nitrogen?
  3. How frequently will the liquid nitrogen be used?
  4. How much two-phase flow (mixture of liquid and gas) can be tolerated?
  5. What will be the peak demand for liquid nitrogen?
  6. Is there a preference for bendable vacuum-jacketed pipe or rigid vacuum-jacketed pipe?
  7. Is a bulk tank or other source already available or will one need to be installed?
  8. What is the timeframe for the project?
  9. Who will be responsible for installation, including tool hookups?