Comparing shop vac and dust extractor performance (data included)

[Frank Pratt]

The difference is that with a HEPA filter you only have that and says nothing else about air and dust leaks. My Festool HEPA vac is well sealed everywhere on it with modest escaping. With my Ridgid vac with HEPA filter, the lid leaks and is not tight.

With the Ridgid vac, at least, the only place for particulates to get past the filter is right where the filter fits onto its seat. Pretty easy to make sure there are no leaks there. If the lid is leaking, it's only allowing air to bypass the suction hose, not the filter.

[Jim Dwight]

Interesting thread. I have two Rigid shop vacs, one for in the shop equipped with a dust deputy and auto-start switch and another for use outside the shop. But my favorite shop vac right now is a cordless Ryobi. It is not as powerful but does a really nice job cleaning the car. I also use it with a floor sweep to clean the floors in the house. Works better, or at least as well, as my house vacuum. And not having to plug and un-plug is great.

Each of my three serves a purpose. I'm sure Festool shop vacs are nicer but I'd rather spend the money on other tools.

[Thomas Marr]

I have 3 shopvac "professional" vacs (model 5872510) with HEPA filters that are very small and rated at 200 CFM (with a normal filter). I also have a CT36. The shopvacs cost just over $125 each and are very portable. The CT36 costs $800 and is not so portable. For the cost of one CT36, I can obviously buy several shopvacs...even dedicating some to specific tools (e.g., the Kapex). I measured the CFM's with the vacs connected to my Kapex and there was little difference. If I had it to do over again, I wouldn't buy the CT36. The shopvacs are not only cheaper, but more useful to me due to their portability.

[Rod Sheridan]

100% agree, Rod. I'm actually thinking of getting a new CT-26 because it's quieter and you can add that neat bluetooth on/off button at the end of the hose

I wish we lived closer, I'm trying to sell my CT26 which is in like new condition.

I really want a Midi which is what I had at first, however it was recalled by Festool and they gave me a CT 26 with handle and a box of 5 bags.

Regards, Rod.

[Larry Frank]

I would like to understand how people measured the cfm of their shop vac. Measuring cfm with such a small hose is difficult to get accurate information.

[Dan Friedrichs]

I wish we lived closer, I'm trying to sell my CT26 which is in like new condition.

I really want a Midi which is what I had at first, however it was recalled by Festool and they gave me a CT 26 with handle and a box of 5 bags.

Regards, Rod.

Well, at least you got a good deal in that exchange!

I actually bought a CT-26 last week and put my Mini on craigslist.

The new hose design is REALLY nice.

[Art Mann]

The variation in velocity from the center to the edge of the cross section of a duct is not negligible. CFM calculations based on center measurements only will be considerably higher than reality. I'm not sure what you can do about it with such a small cross sectional area to measure. Relative comparisons should still be useful if not exactly accurate.

[William Hodge]

It's interesting to see some numbers on shop vac performance.

I turned my Rigid shop vac into a central vac by parking it outside, and running solid plastic central vac pipe into the shop. 2 1/2" hose goes right on the end of the pipe. Reading this post, I guess I have been turning my "Rigid-central vac" into a "dust extractor" by putting a small hose on it for a sander. I did put a 55 gallon drum cyclone right before the shop vac, so only the finest dust ever makes it into the shop vac.

If I ever had to use that screamer indoors, I would be looking at a decibel chart, as well as a cfm chart. I don't have neighbors.

[Charles P. Wright]

I have a craftsman shop vac and a CT26; but pretty much never use the shop vac anymore. I don't know if the CT26 moves as much air; but it is quieter, has a more convenient footprint, and the integrated auto on feature is nicer than the separate plug-in one I was using before for the miter saw. I found that the D27 hose it came with would get jammed on any serious cleanup task, but after I bought a D36 hose and cleaning set I've not had any complaints. I did buy a CT MIDI afterwards to get something that is easier to go up and down stairs (and I wanted a second one so that I could have one in the shop and another in the garage where I'll break down plywood or other place that I'm working).

[Randy Hermann]

Thanks for doing the research on this- always interesting to see real-world data. I'm wondering- did you create the apparatus and essentially leave it alone while switching hoses or did you have to adjust the apparatus each test? I don't know much about fluid flow but it seems that a slight change in position in such a small tube could yield significantly different results? That is a question, btw. and not a statement! You guys know WAY more than I do.

[Dan Friedrichs]

Randy, when I did my tests, at least, I put the hot wire anemometer in a hole in a 5' section of PVC pipe, then just swapped vacs. So hopefully any test-to-test variation due to experimental set up was minimized.