Abrasive blast cleaning machines; high pressure spray equipment for use in treating a surface using pressurized water or air; abrasive blasting equipment for surface preparation and corrosion control; Machines and systems comprising abrasive blast cleaning machines, non-abrasive blast cleaning machines, nozzles for abrasive and non-abrasive blast cleaning machines and structural parts thereof, valves being parts of machines, for blast cleaning a surface; surface preparation and cleaning machines, structural components and pneumatic and hydraulic controls therefor