From 2008 to 2010, I worked in a lab where my primary project was the upgrade of a helium dilution refrigerator so that RF measurements could be taken on a experimental package.  This system, previously used for helium experimentation, was massive.  Huge pumping speed with 6 or 8″ lines, double sealed mechanical pump, roots blower.  This is no small dilution fridge!

df1 df2 df3