Shawn, this was a section of ductwork from my work, they have 1-1/2" flanges on the ends, I routed an opening on the top and sealed the ends to the flanges. Another thing I did since I am going with CO2 gas I wanted to make sure that the return line and drains lines were sealed to the sump so I can put a cover on the sump. Also the DT tank will have glass on top to seal for prevention of off gasing of CO2. Also there is a bypass where I am thinking of inject the CO2.