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

NO.450 Nozzle Bore-1/4″/6.35mm
Length-140 mm
Thread Size:50 mm
Inlet Size:25mm
Air Requirement-80/125 CFM
Horsepower – hp/(kW)- 18/(13.42)

THE AIR REQUIREMENT IS TO ACHIEVE 100 psi AT THE NOZZLE