Portable Pressure Blasters are designed to make the most efficient use of your compressed air and abrasive supply. These are NOT siphon units. The tank is filled with air and blast media under pressure. When the valve is opened, the media/air mixture is released under tremendous pressure. This operation quickly removes rust, paint, scale, and other coatings. Pressure blasters are 3 to 5 times faster than siphon fed machines.