A reactor is a vessel within which chemical reactions take place. Reactors can be used in numerous industrial uses. Surplusrecord sells a wide selection of both new and used reactors. 5 Gallon Reactor Vessel in Stainless Steel. Rated 50 PSI/Full Vacuum internal and jacket. Bottom mounted Lightnin high shear agitator drive. The reason for this is that the reactor is required to be taken from critical to start up. Visit our site for more information about the best industrial reactors.