Abstract: The liquid cooled trap for effectively and efficiently collecting condensable vapor in a chemical vapor reaction system includes two stages. The first stage includes an entrance area to the trap that is purposely designed to be large in space and a very poor heat exchanger in order to avoid condensation and resulting solid deposits that could clog the entrance port to the trap. The second stage comprises a better heat exchanger to spread the condensation and deposits efficiently over a larger surface area and a longer flow path. The second stage is a very efficient heat exchanger to clean up and remove whatever small amount of the condensable vapor remains after the first stage of the trap. The second stage includes cooling coil tubes and cooling cones or fins to increase the overall efficiency of the trap be increasing the interior surfaces upon which the flowing condensable vapor can condense, while not significantly reducing the flow conductance of the trap.