CFM is an acronym for Cubic Feet per Minute. CFM is most frequently used in our industry to measure airflow. Airflow in an abrasive sandblasting cabinet is what gives the abrasive the force needed to do the work or blasting.
Cabinet Turnover and Dust Collector CFM
Cabinet Turnover is a great example of the importance of CFM. Let’s consider a 35″ W x 24″ D x 24″ H Cyclone bead blasting cabinet. If we provide a 90 CFM dust collector, our DC-1500, how many times does the dust collector completely turn over the air in the cabinet? Of course, we’re assuming absolutely perfect conditions. This rarely happens in reality so we’re estimating here.
35″ W x 24″ D x 24″ H is 27,000 cubic inches. Consulting our friend Google, we know that one cubic inch is equal to 0.000578704 cubic feet. So, 27,000 in3 (cubic inches) x 0.00578704 (ft3/In3) = 11.7 ft3 (cubic feet). Again – we are estimating so this is an approximation.
Measuring Cabinet Turnover
Now, divide 11.7 ft3 of cabinet space by 90 of dust collector CFM and we find that the air is completely cycled inside our cabinet roughly 7.7 times per minute.
Why Does it Matter?
Great, we calculated some cool numbers – so what? Cabinet turnover is all about visibility. The more airflow in the cabinet out to the dust collector, the more visibility the user has on what they are doing. Remember, blasting in a cabinet is a dusty process. If you cannot see what you are doing, you risk damaging your parts.
Too much of a good thing?
So if 90 CFM turns it over 7.7 times, what if I want to add 400 CFM to my cabinet? Won’t that increase the turnover? Yes, it will take your turnover to about 34 times per minute. Unfortunately, that amount of CFM won’t improve visibility in that size cabinet much more than the 90 CFM unit.
We supply our 90 CFM dust collector with most of our cabinets. This is because the cabinet size and thus cubic feet inside the cabinet are appropriately matched to a 90 CFM dust collector. For our larger cabinets we advise the addition of a 400 CFM (Model DC-4000) dust collector to achieve good visibility.