ABSTRACT
In cryogenic systems for the liquefaction, separation, and purification of gases, one has to
deal with temperatures of around 112 K for liquid methane, and as low as 4.2 K for liquid
helium. The design engineer, therefore, has to provide adequate insulation for the processing
and ancillary equipment subjected to these very low temperatures, in order to reduce the heat
gain to a practical minimum. Any heat gain from the outside ambient atmosphere means a
corresponding loss in refrigeration applied to the process cycle. Since the cost of externally
applied refrigeration, energy for compressors, mechanical refrigeration units, far outweighs
the cost of insulation, it is therefore prudent to spend the necessary time to study the
requirements for insulation, instead of leaving it in the hands of others or of the cheapest
insulation supplier. The lower the processing temperatures, the greater the need for properly
specified insulation, in terms of type, quantity, quality, and density. For industrial purposes
any temperature lower than 120 K may be considered as in the field of cryogenic processing.
