When sucking on a 5 lb batch of beans to cool them, the aluminum tubing running into the suction of the sucker / blower fan gets hot enough to give you blisters. When sucking on a 2 lb batch, it gets hot enough to blister (I don't learn very fast do I?)
You are sucking the air off of 425 degrees plus beans, and if you are running it through a plastic / vinyl vacuum cleaner hose, it may very well melt it, or possibly the plastic impeller of the vacuum. Use with care.
Aaron