1.15. Consideration of Characteristics of Accessory Materials

1.15.1. Vapor Barriers

Condensation of water will occur on surfaces at temperatures below the atmospheric dew point, due to water vapor drawn towards the cold surface as a result of the difference in partial vapor pressure between the air at ambient temperature and the temperature of the cold surface. Unless it is possible for this moisture to be re-evaporated, it can be absorbed into any permeable insulating material that may be applied to the cold surface, thus increasing the thermal conductivity of that material, with impairment of its effectiveness.
The purpose of the vapor barrier is to reduce, and if possible to prevent, the ingress of water vapor into the insulating material, Thus, ...

Get Thermal Insulation Handbook for the Oil, Gas, and Petrochemical Industries now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.