So basically I've been giving the task of installing the prep and semi-prep normal phase columns on our shimadzu hplc system. The tubing has a 1/6 inch diameter and the semi prep column has the same diameter; so hooking that one up was no problem. The prep one however, has a 1/8 inch swagelok fitting. I've been told to go from the 1/16 inch tubing on the machine to the 1/8 inch column, I will need a reducing union. I'm curious if anyone has any experience in this area and if you do recommend the 1/16 inch tubing to the 1/8 inch column or should I replace all the tubing to 1/8 inch because of possible pressure concerns? Column will handle up to 1kpsi but I'm not sure of any of the possible issues that the tubing will face in doubling the diameter at the column.