I bought a -100*C refrigerated cold trap from a surplus sale, which was not operational. In this video, I describe how the unit works after recharging its second stage with R1150 (ethylene) refrigerant. Savant RVT4104 - (manual) http://phoenix.tuwien.ac.at/chemistry/Gebrauchsanweisungen/SAVANT%20Vapor%20Trap.pdf