Rotary evaporator bump trap is used between the vapor tube and evaporation flask on a rotary evaporator to prevent contents of the flask from being drawn into the condenser in the event of “bumping”. Unique elliptical shape provides large trap volume while decreasing the overall length when compared to standard spherical designs. His allows the use of larger recovery flasks in a rotary evaporator. Traps have a 24/40 top outer joint and the listed size of lower inner joint.