Dyplast Products is releasing the final installment of its 3-part series of Technical Bulletins to address "Logical Thinking" when specifying mechanical insulation for very cold/cryogenic applications. In this document, we continue our discussion about how the environment at very low/cryogenic temperatures is very different from the ambient conditions sometimes set by the test protocols of many standard organizations. 

In this third Technical Bulletin, we address water vapor transmission, water absorption, strength, and dimensional stability. As an example of logical thinking, consider this short quiz regarding water vapor transmission: 

  1. If the insulant has a positive WVT measured at 75ºF, what is the WVT when the temperature of the inner insulant drops below the dew point? - - then below freezing?
  2. To what extent does a "high" content of water vapor within an insulant reduce thermal performance?
  3. If the insulant itself has zero WVT, can the insulant actually absorb water?
  4. Logically thinking, if 'vapor' cannot exist at cryogenic temperatures, why is WVT important at all?

In Part 1 and Part 2, we considered: 

  • Concepts of Logical Thinking
  • Thermal conductivity (lambda or k-factor)
  • Differences in ASTM standards and testing
  • Lambda versus temperature
  • Insulant aging
  • Heat transfer
  • Radial (pipe) dimension effects
  • Due diligence

We hope you will take time to peruse the documents, and that they may be helpful in your decision-making process.