When it comes to an abrasive sandblasting cabinet there are many options. Arguably the most important is whether you choose a direct pressure or a siphon fed media bead blasting cabinet. If you are looking for a refresher on bead vs. sand vs. media terminology you can read our documentation. It’s basically about what comes out of the blasting gun. More importantly with siphon vs. direct pressure it is how powerful the stream is coming out of the blast gun.
Siphon Fed also called Gravity Fed
A siphon feed blasting system uses something known as the “venturi effect/principle” and draws abrasive media up a tube and out the blast nozzle. High pressure flow from an air compressor passes through a constricted section of the blast gun and creates a difference in pressure where the media tube connects. It is this difference that draws the media up through the blast gun and out the blast nozzle.
Siphon feed blasting systems are adequate for most users providing abrasive media is available and pressure is constant. Siphon feed blasting systems work well with almost any media except steel shot. This is a very heavy abrasive and Siphon Feed systems do not provide sufficient “draw” to pull the media up from the cabinet hopper and out the blast gun.
Pressure or Direct Pressure
These systems utilize a pressure vessel, or a “pot”. Don’t settle for any pressure vessel that does not carry an ASME (American Society of Mechanical Engineers) approval. Abrasive media is poured into the pot and then the pot is pressurized. The user then opens a valve and the pressure flows out of the pot carrying the abrasive with it. Pressure pots can be connected to a cabinet or they can be stand alone units like our PT-100 and PT-100-SK. We also offer a direct pressure blasting cabinet, our DP 38.
Direct pressure units can reside on a blast cabinet or as with our units roll on heavy-duty wheels. Direct pressure units provide sufficient energy to push any type of abrasive, at a lower pressure than siphon units.