I have a model venturi Ive created useing a air compressor letting the compressed air out of a small nozzle at the end of the air hose attached to the compressor. The nozzle is placed within a pipe causing the release of air directly torward the right of the pipe then to atmosphere leaving very little restriction within the pipe. The left of the pipe is a sealed system which has about 25cfm of air spilling from it into the left of the pipe.ó Simply put, how do i calculate the needed amount of air needed to pass through the nozzle into the pipe to create sufficient suction to pull the 25cfm from the left of the nozzle to the right and leave a less than atmospheric pressure behind the nozzle. (Leave a minor vacuem) The variables i have are: pipe diameter 1.5" available cfm from compressor is available up to 120cfm. I may be overcomplicating the obvious, but the goal is to scavenge the 25cfm constantly as effectivly as possible.