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

NO.650 NOZZLE BORE-3/8″/9.5mm
LENGTH – 175mm
Thread Size-50mm
Inlet Size-32mm
Air Requirement-250/270 CFM
Horsepower-hp/(kW) 45/(33.56)

THE AIR REQUIREMENT IS TO ACHIEVE 100 psi AT THE NOZZLE