This system is similar to the above with the exception that the air pressure pushes the sand through the hose to the nozzle. A larger volume of sand can be carried this way. Here an air compressor is required to generate the air flow under pressure.
The sand can be made of various hard materials: Garnet, Silica, various oxides, etc. It is filtered and refined to a specific size, all depended upon the application.
The sand is carried by the high velocity water that is generated in the nozzle. The high velocity water jet in the abrasive nozzle accelerates the sand. In this system the water jet inside the abrasive nozzle creates a vacuum that pulls the sand from the container to the nozzle.