Question: Do you have a chart which shows the minimum pressure blaster nozzle size required for each of the mesh sizes of blast media?
Response: A reasonable guideline for proper media flow would be to use a nozzle bore size that is 7-10 times the average particle size of the abrasive blasting media you are using.
Note: See Mesh and Micron post to get a rough formula to convert from one identification to the other.