Originally Posted by
Doug Dawson
It gives a simultaneous output in two particle sizes, let's describe it as n|N, where n is associated with 0.5 micron particles, and N is associated with 2.5 micron particles. It's not an exact measurement, although Dylos can provide you with all kinds of formulas to make that connection, but it's a relative quantity, for comparison purposes. The Dylos is on a shelf over my left shoulder when I'm standing at my workbench.
I have a Festool CT48 shop vac, which I use to collect dust from my Festool sanders etc. When I'm sanding, which I may do for hours on end, I usually have the Jet overhead on low speed, which keeps the N numbers down. The n will tend to hover around 600 or so in the steady state. When I turn the PM1250 on, typically medium here, n will tend to hover in the 200's as a steady state. When I'm done sanding, n will get down to 60 or so within an hour, with the PM1250 on. The PM1250 mostly affects the n numbers, i.e. the 0.5 micron size particles (i.e. particles with size of that approximate magnitude.)
I had to open the shop to roll a car in there yesterday, with the garage door open n|N was 160|30, IOW ambient here. After closing the garage door, with the Jet on low for 20 minutes, N dropped down to 6 or so, and with the PM1250 on low for about 3 or 4 hours afterwards, n|N stabilized at 12|0. This is in an active woodshop, with a dirty dusty car just rolled into it. n=75 or less is considered "excellent" by the Dylos people.
YMMV. These are just my most recently observed numbers, in my own workspace.
Is that HEPA enough for you? :^)