Performance boosts to small shop DC machines

[memilanuk]

So... I went and saw a man about a dust collector today... picked up what looks to be a lightly used 50-760 with some extra hoses and fittings, plus a 50-860 air cleaner for $200 total.  I'm happy  ;D

Anywho, over the last week or so I've been going back through various threads on different forums and looking at some of the nifty 'improvements' that people have worked on to these smaller machines like the HF 2hp, Delta 50-760, and Jet DC1100 units.  Wynn filters, various incarnations of the Thien baffle separators with 4, 5 or 6" piping, bell mouth discharge pipe, round-to-rectangular intake pipe, air straighteners, etc.

The stuff I've read seems to demonstrate a small but noticeable improvement with the last three or four modifications, at least judging by the current draw, if I read those threads right.  My understanding of that testing was that the assumption was/is that various changes resulted in higher and higher current draw, implying that the motor was working harder by pushing more air - except for the air straightener 'pipes' where it was theorized that the lower current read was due to the motor *not* having to work as hard due to less turbulence in the air stream entering the impeller housing.  While thats all well and good and I don't necessarily disagree on any particular point...  what I'm kind of curious about is if anyone has done testing of actual changes in either air flow or static pressure?  I realize that requires a different set of test equipment that is not exactly commonly available - but I am curious if anyone has attempted these more 'direct' measurements?

The other thing I've been wondering about... the Wynn 35 series filters seem to be commonly accepted as an improvement over the stock bags, even if they have supposedly identical ratings i.e. 1 micron factory felt bag vs. 1 micron pleated filter (assuming the factory bag rating is accurate), due primarily to the increase in air flow as the surface area increase from 20-30 square feet to 100 or more for the Wynn cannisters.  Again, maybe I missed it... but has anyone tested/confirmed the improvements in terms of air flow in CFM or SP at the intake, or even just current draw on the fan motor if nothing else?

TIA,

Monte

[retired2]

There is CFM test data in the thread on my separator build.  The readings were done using the same anemometer and procedure used by Phil.

Here's the link:
http://www.jpthien.com/smf/index.php?topic=563.90

I did not test SP, but you can use the CFM data and the fan curve for the DC to get a close approximation of the SP.  The fan curve can be found in a test of several DC's that has been posted several times.  If you can't find it let me know and I'll repost the link.

[memilanuk]

Ah.  I remember wading through that (long) thread; I'd forgotten that the table had both amps and cfm in it.

Do you know of any similar testing/quantifying for the Wynn cannister filters?

Thanks,

Monte

[retired2]

The only testing I know of was the test I did with no filter at all.  Running the system with no filter did not produce a significant improvement over my green bag filter, and obviously a Wynn filter can't improve on no filter.  I have not retested my system now that the filter bag has some cake, but I can see it is not working as quite as well.  I would assume replacing the bag filter now with a Wynn filter would show some improvement.

[memilanuk]

Yeah... that was the bit that didn't make a lot of sense.  For all the hoopla made about the increase in air flow from a cartridge-type filter, and all the anecdotal accounts of 'I could feel a big increase in the suction after adding a Wynn filter!'... and then the results table seems to show basically no change / maybe a slight decrease (probably within instrument error) in air flow with the bag completely removed?

Very odd. 

Almost makes me want to duplicate some portion of the test just to see if the results would track or not.  I haven't seen my Fluke 33 ammeter in *years*, though and I would have to find/make a manometer ;)

[phil (admin)]

Yeah... that was the bit that didn't make a lot of sense.  For all the hoopla made about the increase in air flow from a cartridge-type filter, and all the anecdotal accounts of 'I could feel a big increase in the suction after adding a Wynn filter!'... and then the results table seems to show basically no change / maybe a slight decrease (probably within instrument error) in air flow with the bag completely removed?

Very odd. 

Almost makes me want to duplicate some portion of the test just to see if the results would track or not.  I haven't seen my Fluke 33 ammeter in *years*, though and I would have to find/make a manometer ;)

The resistance of the separator (any separator, not just my design) is proportional to the speed of the airstream squared.  So beyond a certain point the resistance just eats-up any additional CFM.

So if you find that by removing any filters you don't see any more airflow, you're already operating at the top-end of a separators range.

In my case, adding my separator to my shop vac reduces CFM by about 25%.  But if I add my ductwork to the picture, the separator only reduces CFM by approx. 14%.  This is because the ductwork reduces the airspeed to a point where the resistance of the separator drops significantly.

Make sense?

[memilanuk]

Hmmm... hadn't thought about in terms of things already being maxed out.  That does make a certain amount of sense ;)

FWIW... I was going back through that Wood magazine article from issue #182 that gets linked to a lot, and I may have found a partial answer to my question:

...using a high-efficiency filter on the top and a nonporous plastic bag on the bottom added 40–80 CFM of airflow versus 30-micron bags. And although stepping up from a 5-micron to a 1-micron bag didn’t improve airflow in our test, it will boost your shop’s air quality.

From looking at their fan curves it appears that the tighter/finer filter bags (aftermarket 1 micron & factory 5 micron) and cartridge filter (factory 2 micron) all had about the same CFM and SP - the curves pretty much overlapped one another.

Short of anyone doing testing specifically with the Wynn cartridge filters instead of an OEM Jet cartridge... looks like that pretty much answers what I was asking - whether going from the factory Delta 1 micron felt bag to an aftermarket cartridge like the Wynn - or from the spun bond polyester to the nano fiber media - would yield a meaningful difference in the CFM/SP of the system, all other concerns aside.

Not enough to measure, apparently.

Part of why I was asking is that I've seen it suggested that one needs approximately a 1:2 ratio between filter surface area and air flow in CFM, which most filter bags fall far short of (Pentz).  Evidently I didn't read that *fully*... the reason appears to be less to increase air flow through a less restrictive filter, but more to prevent excessive loading during use and premature failure due to cleaning.  So there may still be incentive to 'upgrade' to a cartridge filter... though after building a good separator baffle to keep most of the crap *out* of the filter in the first place, that may go down somewhat ;)