In order for any filter to meet True HEPA Filtration, one simple standard must be met: a minimum particle removal efficiency of 99.97 percent. In order to achieve this rate, the air moving through a HEPA filter must be at or below 5 CFM per square foot of filter. Any air movement that goes over 5 CFM per square foot, efficiency drops below 99.97 percent thus depleting the qualification.
Looking at the sandcarving industry specifically, let’s put numbers on paper. Say a sandcarving machine has a 15 square-foot filter, a maximum of 75 CFM of air movement qualifies this filter as true HEPA filtration. If the air movement in that machine goes above 75 CFM, this is not True HEPA Filtration. Looking at another angle, say a sandcarving machine is running 750 CFMs, a total of 150 square feet of filter must be present in the sandcarving machine to qualify. This is not really plausible or effective.
It’s important to check the numbers and do the math especially if your current sandcarving machine is coined as “True HEPA Filtration.” If your facility needs to meet specific standards or if anyone on the shop floor has allergies, it’s important to know the truth and facts behind True HEPA Filtration. The equation is simple: If the CFM divided by the square footage of filter equals 5 CFM or less, then you have True HEPA Filtration. If the number is higher than 5 CFM, then you do not.
-Wes Barton, IKONICS Imaging
