Placed between the vapor tube and evaporation flask, rotary traps prevent a flask’s contents from being drawn into the condenser if they are bumped. Rotary traps also serve to provide expanded volume for reactions that are noted for excessive foaming, while a sealed-in fritted disc aids in reducing foam from being carried over. The inner vapor tube on a rotary trap is sealed to the top of the trap, which prevents entry into the condenser, while drain holes at the inner tube’s base allow solvent to drain back into the evaporation flask. Rotary traps are typically manufactured from borosilicate glass, which offers strong resistance to temperatures.