What is a Blast Cabinet Dust Collector?
A blast cabinet dust collector primary purpose to improve visibility inside a sandblast cabinet. Secondarily, it contains the dust and debris it collects. We cover the second point in Part 2. For this article we focus on visibility and how to achieve it. During the sandblasting process, the abrasive is airborne and breaks down causing dust. Dust and debris from parts inside the cabinet are released too. These factors combine and make seeing inside during blasting difficult. That’s where a dust collector comes in. In this article we cover the basics.
What does it do?
On the most basic level, the blasting cabinet dust collector acts like a household vacuum. A motor and impeller create pull the air away from the interior of the cabinet. Along with the air comes with the airborne dust and debris. Although very simple in concept there is actually a lot to consider with a blast cabinet dust collector compared to a household vacuum. In part 2 we will compare the sandblasting dust collector to a household vacuum.
Before diving into the details, think about a time when you might have put your hand over a vacuum hose. You can clearly feel the suction against your hand. Release your hand and the surrounding air rushes into the vacuum. That air is from the room you are in. The vacuum is pulling as much of the air as it can. When we think about a blast cabinet dust collector, the situation is slightly different.
Blast Chamber Turnover
The blast cabinet chamber is nothing more than the inside of the sandblaster. It is where the work is done. We need to think about chamber size for a few reasons. As we will see, the term to keep in mind is turnover. Turnover is simply how many times the air in the cabinet is removed and replaced. The air turnover is done by the dust collector. Turnover is important because it relates to visibility inside the cabinet. Visibility is important because you want a very clear view of what you are working on during blasting. In general terms, the more turnover in a cabinet the better the visibility. There are some exceptions but we will start by looking at all the important parts of blast cabinet dust collection and then learn more.
Blast cabinet selection begins with sizing the chamber for the parts that go into it. The interior measurements are also important for dust collectors too. The interior of a blast cabinet is measured in volume, typically cubic feet or cubic inches. It’s the rough height x width x length. Most sandblasting cabinets are not perfect rectangles so we tend to approximate the volume. For simplicity, consider a perfect blast chamber that is 1 foot wide by 1 foot long, by 1 foot high. 1 ft x 1 ft x 1 ft = 1 cubic foot of airspace inside the chamber. Keep this in mind as we move forward in our discussion.
Cabinet Construction and Air Exchange
Another factor in dust collection is to consider is the construction of the blast cabinet. A good quality blast cabinet is well sealed to prevent leaks during blasting. Solid welds, sealants and good gaskets make this certain. Why does this matter? A quality blast cabinet is nearly airtight, as it should be. Therefore, the dust collector eventually pulls almost all the air out of the cabinet. Adding an air inlet to the cabinet addresses this problem. But, how can you do this without having dust and debris leaking? After all, holes in a cabinet will lead to leaks. Or will it?
A good blast cabinet has a properly baffled air inlet. This inlet is usually on the back or on one side of the cabinet and allows fresh air to enter into the chamber as the dust extractor pulls air out. A baffle surrounds the inlet and prevents dust and debris from escaping. Air entering through the inlet and extraction via the dust collector is air turnover (as mentioned above).
Abrasive choice is an often overlooked aspect of dust collection. When you blast, your cabinet is pushing media at the surface of a workpiece. When the media impacts, it is met with an equal force in the opposite direction. As a result, the process removes the “stuff” you want off the workpiece. Also as a result, the abrasive is eventually broken down. Much like sandpaper eventually wears as you use it, so does blast abrasive. When the abrasive breaks apart it creates airborne dust that decreases visibility.
Putting It Altogether
Remember, the basic goal of a dust collector is to improve visibility inside the cabinet during blasting. In order to do this, the dust collector must remove air from the cabinet. A baffled air inlet brings fresh air into the cabinet, thus turning over the air.
A blast cabinet’s shape is, as we discussed, not a perfect rectangle. The angle where the view window exists is the reason (in most cases). Let’s use a real-life example. We will use our 5532 cabinet as the blast chamber. Next, we compare our DC-1500 and DC-4000 dust collectors to demonstrate how turnover and visibility changes with dust collector size. Finally, we throw in an 800 CFM example too.
Real World Example — Sandblasting Dust Collector System
The 5532 is 55” Wide, 32” Deep, and the heights are 14” (Front) and 27” (Rear). Since we’re in a real world example, we have heights to consider in the 5532 diagram below. We did the math and ignored the hopper’s volume for this article. The overall volume of the blasting chamber in the cabinet is roughly 24 cubic feet. The formula for turnover in a blast cabinet is:
So that’s really neat math but it proves what you may already know. The more powerful the dust collector the more turnover. Thus, the better visibility inside the cabinet. However, as you increase the dust collector’s CFM you are likely increasing your investment cost. So, how do you know what size to get? In short, it deals with the density of the media you’re using, what you are blasting, and how much/long you are blasting.
How Abrasives “Impact” Turnover
Take for example steel shot compared to garnet (a sand like abrasive). Steel is much more dense than sand. In a blast cabinet it will break down much slower than garnet. As garnet breaks down during blasting, it produces more and more dust inside the cabinet. Therefore, when using a lower density media you may want more turnover in the cabinet to make visibility better.
Additionally, if you are blasting a piece of steel pipe compared to blasting dirty old wood, you will create more airborne debris with the wood. That would also be a better scenario for a higher turnover. We dug back to an article we found from the 1970s and their recommendations still apply today. Turnover rates between 1.2 and 1.3 times per minute are “satisfactory.”
Cyclone Blast Cabinet Dust Collector Systems
We want to educate our customers on what we offer in our industry. We include properly sized dust collection systems with our blast cabinets. The air turnover in our cabinets will not disappoint and will make visibility nearly perfect during blasting. We manufacture cabinets that properly baffle inlets to eliminate leaks. Our dust collectors include many very important features that we discuss in part two of this article. We hope that you enjoyed this article. Our sandblasting dust systems are listed on this page. Thank you for reading, part two will be out soon!