We have a picture where the various layers of a transfer line are labeled.
One of the labels reads “n layers of superinsulation…”. We were thinking either the “n” stands for something (but we don’t know what) or it is a typo. Any thoughts on what the “n” means?
What does "n" stand for?
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1 Comment
Dr. Thomas M. Flynn, Cryoco
April 28, 2009No problem. “n” means the number of layers in the jelly roll. SI is made by laying metallic foil (Al usually) on a film of a non-conductor (PP=PPE= polypropylene, for instance) then rolling if jellyroll fashion around the cylinder to be insulate. n=25 layers is the standard.
n layers of super insulation {both sides of the PET Foil Al coated with PP spacer fleece between the layers.
In this case, they use PP as the thermal insulator between the foil layers. PP=polypropylene. It doesn’t matter much what film thermal insulator is used, mylar is common, also Kapton. The choice depends upon flammability (if liquid oxygen is contemplated, and ease of application, durability.)
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