For this size Blast nozzle here is the size and the air required for best performance

NO.550 NOZZLE BORE-5/16″/8.0mm
LENGTH – 150 mm
Thread Size-50mm
Inlet Size-25mm
Air Requirement-150/170 CFM
Horsepower-hp/(kW) 30/(22.37)

THE AIR REQUIREMENT IS TO ACHIEVE 100 psi AT THE NOZZLE