Airflow increase from cannister filters

[Monte Milanuk]

Hello there,

I recently picked up a Delta 50-760 dust collector with a stock '1 micron' felt bag, and am looking at upgrading to a cartridge-type filter (probably a Wynn 35A). I see a lot of posts on different forums saying that going from the OEM felt bags to aftermarket cartridge should, or did, result in an increase in air flow due to the increase in surface area (in this case ~20 sq ft for the stock bag to ~275 sq ft for the Wynn filter)... but I don't think I've been able to find anything saying 'how much' in quantifiable terms.

Anybody know of any tests/measurements that would help with this?

TIA,

Monte

[Alan Schaffter]

I don't have any links to tests, but initially the flow may be better. The BIG problem putting a cartridge on a single stage DC like the 50-760 with no pre-separator or cyclone is that the cartridge will clog just as quickly as the bag. Once that happens your suction will drop off considerably. Cleaning must be done often and it can be difficult to remove dust from deep in the filter pleats. Some dust will permanently clog and reduce the capacity of the filter. If you are not careful you can permanently damage the cartridge attempting to clean with a beater stick or compressed air.

At the price of cartridge filters, you would be better off using some type of pre-separator to remove as much of the chips and dust as possible while discharging the remainder outside without using a bag or cartridge filter.

[Jamie Buxton]

I did that exact "upgrade" -- canister on a bag-type DC. The problem was that the dust caked up on the inside of the canister, and there was no easy way to clean it off. You'll notice that most of the DCs with that arrangement have a beater inside the canister, so you can easily knock the dust down into the bag. You might better acquire a canister-plus-beater from Delta or Jet or the like. Me, I went back to the top bag, then sold that DC and went with a cyclone.

[David Kumm]

I would talk to Dick Wynn and get his advice. Cartridges do load up if you are sanding and you want a surface loading cartridge that blows out easily if that is the route you go. Brushes inside cartridges are not a perfect answer in that they can degrade the filtering capacity and turn a 1 micron filter into something worse with constant use and only your lungs will know after it's too late. Dave

[Joseph Tarantino]

this enhancement to almost any dust collector drum ring will send more chips and fines to the collection bag, keeping them out of the filter:

http://lumberjocks.com/topics/40189

less "stuff" in the filter = greater air flow and dust collection performance.

[Kevin W Johnson]

A seperator is pretty much a must no matter if you have a bag or cartidge filter. Either filter clogs up fast without a seperator, and you lose airflow. With my seperator, almost nothing at all ends up in the filter or the cllection bag beneath it.

[ian maybury]

One additional issue is that strictly speaking cartridge type filters are best/intended to be used in installations that deliver outside to inside air flows. i.e. the air comes into a chamber which has one or more cartridges mounted over the exhaust(s). This means that whatever dust accumulates does so on the outside surface which is somewhat easier to clean - although it's not going to eliminate the basic reality that a cyclone or some sort of separator (while it reduces air flow initially by increasing pressure drop by something between 1.5 and 4in Wg depending on the design) is probably advisable to maximise filter life.

They get mounted the other way on many DIY level dust systems because it saves on ducting etc. - to mount the other way typically requires building a cabinet.

The one exception to using separation that's commonly about is the Felder type cabinet unit - they don't seem to have separation - but seem to do a decent job as you don't hear people complaining about short filter life. Maybe they have a lot of area, or there's something different about the type of filter they use?

ian

[Monte Milanuk]

Yes, folks I am planning on using a separator - no way I'd spend the $$$ on a cartridge filter just to plug it up with crap every time I used it.

Now back to the original question...

[Michael W. Clark]

I bet you will have as much or more drop across the separator than you will gain from the larger filters. It could actually reduce your overall exhaust volume.
However, the new flow will be more sustainable with the reduced loading in the filters and the filters will be much less likely to blind and easier to clean.
If you can reduce your system losses, you may be able to improve your flow.
Mike

[Greg Peterson]

Phil Thien baffle.

http://www.sawmillcreek.org/showthre...-Baffle-Barrel

[Monte Milanuk]

Holy cow.

Greg, see my last reply. I do intend to build a Thien-type baffle, FWIW. I don't need another half-dozen replies telling me to get a separator, or what kind - it isn't relevant to the question at hand.

Mike, yes, I understand that. A cursory review of threads on various forums indicated that the drop across the separator will be significant, albeit necessary to keep from plugging the filter and maintaining some level of performance. And that the increase in flow through the aftermarket filter should help alleviate that somewhat.

I GET THAT, folks.

What I'm asking, is 'How much?'

[Monte Milanuk]

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

[Kevin W Johnson]

Holy cow.

Greg, see my last reply. I do intend to build a Thien-type baffle, FWIW. I don't need another half-dozen replies telling me to get a separator, or what kind - it isn't relevant to the question at hand.

Mike, yes, I understand that. A cursory review of threads on various forums indicated that the drop across the separator will be significant, albeit necessary to keep from plugging the filter and maintaining some level of performance. And that the increase in flow through the aftermarket filter should help alleviate that somewhat.

I GET THAT, folks.

What I'm asking, is 'How much?'

Holy cow is right. Thanks for the attitude. The people here are simply trying to help, try not to be so...... brash.

How much is not easily quantifiable, thus you won't get that exact answer, as there are too many variables and very very few people have the equipment needed to measure it.

[David Kumm]

Monte, it is almost impossible to predict how the filter change will impact the cfm from a distance. Every unit has a flow curve that maps cfm vs SP. You need to know not only the curve for your DC but how much SP you have with various ports open. If your system has low resistance because of short runs, few ells, little flex, the reduction in resistance from adding surface area in the filter is much different than if you are at the higher end of the pressure range the difference might be more significant. Each filter media has its own recommendation for area per cfm. Nano filters are tightly pleated and 2 cfm per ft is about right. I would guess the upgrade will reduce resistance 1-2" so if you have a system curve you can figure out the cfm increase. Dave

[Greg Peterson]

Holy cow.

Greg, see my last reply. I do intend to build a Thien-type baffle, FWIW. I don't need another half-dozen replies telling me to get a separator, or what kind - it isn't relevant to the question at hand.

Sorry, just trying to help. You mentioned you were going to use a separator, which is entirely different device. I won't make this mistake again. Have a nice day.