Hey Ed, What Is the Most Appropriate Velocity Moving Across a Filter?

In This Edition of “Hey Ed,” Ed Discusses the Most Appropriate Velocity Moving Across a Filter

Hey Ed, what is the most appropriate velocity moving across a filter? My favorite target velocity is a number that you can find listed in Manual D®. It doesn't say what the velocity should be for a filter itself. What it's referencing is a filter grill, but I take that to be my number as what I'll call the gold standard. My target velocity is 300 feet per minute or less. Some of the manufacturers of filter grills, if you follow their guidance, will be a CFM versus square inches of surface areas. Along those lines, those numbers come out well under 300 feet per minute. Lower velocity, better filtration, and lower pressure drop can lead to more energy-efficient operation, and that's always going to be a positive. And that's the way I see it.

In This Edition of “Hey Ed,” Ed Discusses the Most Appropriate Velocity Moving Across a Filter