Complete, two-piece, jacketed flask, pressure reactor system designed to perform low to moderate positive pressure reactions, synthesis and catalysis. Reactor capacities range from 500ml to 5000ml and use Ace-Threds to achieve a leak-tight system. Two-piece (flanged flask and head) design allows the use of large agitators and facilitates product removal and clean-out. Rated 36PSIG at 100°C. Reactor bodies, codes -09 thru -26, have 28/15 ball joint inlet/outlet while codes -309 thru -326 have Ace-Thred inlet/outlet.