Suction vs. Direct Pressure Blast Cabinets

The two basic types of abrasive blast cabinets are suction (or siphon) systems and direct pressure systems. While both types provide reasonable performance and high value, certain processes and applications will be better served with one type or the other.

Suction Blast Cabinets
This type of blast system contains an air jet in the blast gun that passes high velocity air over a media pick-up hose creating a siphon or suction effect. The media is pulled up through the hose and propelled out of the gun to the surface to be blasted. This is commonly used for light production applications and for general purpose cleanup and touch-up work. Suction systems are relatively inexpensive systems to purchase and operate.

Direct Pressure Blast Cabinets
A pressurized blast pot is used to force media out of the nozzle towards the target. The pressurized air pushes the abrasive at faster velocities than suction systems. Many processes can be completed 30-50% faster with a direct pressure blaster. Due to the higher flow rate (and
more force), pressure blasting offers the additional advantage of allowing for lower blast pressures ideal for delicate and sensitive surfaces.

Abrasive Blasting Cabinets

The choice of abrasive blasting cabinet needs to made based on the type of blasting being done including the media type and frequency of blasting. The primary benefit of a blasting cabinet versus a portable system is the containment of the media allowing for re-cylcing. Many re-usable blast media are abrasive and demand a durable cabinet construction and heavy duty fittings and nozzles.

A cabinet constructed of continuously welded 14 gauge or thicker steel will provide long-term wear with most blast media. Adding optional rubber mats (if available) to the inside of the cabinet will further increase the lifetime of the cabinet. Accessories such as heavyweight gloves and long-lasting tungsten carbide nozzles are also worth the additional expense. A nice addition is an underlayment on the inside of the window to prevent etching of the glass and keep operating costs to a minimum.

The selection of a siphon/suction or pressure cabinet will be described in another post. This decision will impact overall operational efficiency and performance. The blasting cabinets offered by Trinity Tool Company (Trinco) are excellent examples of the proper construction for long term durability and high value.

Portable Abrasive Blasting

There are two ways to abrasive (sand) blast using a portable system - pressure blasting and suction or gravity fed blasting. Both systems have advantages and the choice is based on the application and the usage. A variety of dry blast media can be used with either blasting method. As always, it is important to make sure the nozzle size being used is proper for the media grit size being blasted.

Suction or gravity fed blasting involves sucking or pulling media from an open container using a blast gun. The air jet inside the gun passes high velocity air over the media pick-up hose 'pulling' the media out of the nozzle with the air. This type of system is inexpensive and simple to use but the process is inefficient and takes a long time. This type of process is designed for small jobs.

Portable pressure blasting requires loading a pressurized pot with media that is forced through the hose and the nozzle. These types of systems are designed with a wide range of pot sizes (with a large cost range) and can be used with many different sized nozzles. Pressure blasting is very efficient and is the absolute choice for industrial and commercial (heavy duty) blasting applications. For industrial-grade portable pressure blast systems we prefer ALC.