Heavier / dense blast media may need a pressure blast system consideration to enable sufficient media flow to be achieved. As described in the pressure blast cabinets and systems introduction Part 2 heavier and denser medias may not be capable of being delivered by a venturie / suction system because it requires sufficient energy to bring the blast media up the delivery tube to the blast gun and the system becomes inadequate.
The density/weight of a blast media must be taken into account when calculating both the volume and pressure of air required. For larger blast media (i.e. S330 Shot or G25 Grit and larger) with a high density, the ratio of air to blast media will change (i.e. more air, less media) to enable the air to carry and suspend this dense media to the delivery point (the blast nozzle).
Each particle of dense blast media is capable then of picking up momentum from the air speed movement and when combined with its own mass (size/weight), will be delivered through the nozzle to the work with much more energy.
Conversely, lighter, less dense blast media such as finer plastics, fine aluminas or finer glass bead of 100- 205 micron require less volume and pressure to enable the delivery to perform well. In these cases, the air to blast media ratio will be balanced to a higher percentage proportion of blast media resulting in a quicker saturation/coverage of the surface.
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Post written by
Shot Blasting Technical Manager