I am interested in Copper Inner-grooved Tube, nom. size 6.35mmOD/ 0.250 inch. We want to increase our liquid nitrogen-LN2 heat transfer coefficient above smooth bore Cu tubing for use on our high temperature super conductor Flux Conserver at a pressure not more than 1 bar (15psig) and flow rate 0.75 l/m (0.2gpm), located inside an experimental plasma vacuum vessel. Our use is not typical ACR/heat exchanger usage. Our immediate need is for a small quantity of tube (20-50 feet/7-15m.) for next step in the proof of principle before advancing phase and scope of our project. Cost and minimum order USA Dollars, do you have a USA representative? Would a sample be available for test and evaluation? If no USA distributor or large minimum order requirement is there a possibility of a previous customer of the 6.35mmOD that might be willing to sell some of their inventory? Thank you,John Gumba