Successfully pumped down emergency GV hood prototype! After vulcanizing two 1/4" diam. o-rings and sealing via one band clamp, the volume pumped down to fractions of a torr. Using aux cart, pressure at turbo read 9.1e-3 Torr with a hefty foreline pressure of 3.2 Torr. I will try to improve hole plugging. I want to test the 6" gap calculation incrementally to see if the polyurethane withstands the atmospheric pressure differential as predicted.