What makes Al-Ko (or Felder RL) dust collectors so quiet?

[Dan Friedrichs]

I guess the "typical" dust collector is a 3450rpm motor with a ~16" impeller, which makes quite a lot of noise (beyond just the noise of air movement). But I've heard that the Al-Ko style dust collectors (or ones like the Felder RL-125) are markedly more quiet. Why is that?

[Jim Becker]

I will guess that they used a different kind of blower system to generate the air movement required for dust collection. Again, that's a guess. They are also fully enclosed systems which is going to cut down on noise transmission, too.

[Jamie Buxton]

Felder sure is close-mouthed about those dust collectors. They don't seem to be cyclones. As far as I can tell, they just have big filters, with the blower sucking air through them. I'm guessing they have some sort of cleaning system to knock the dust off the filters.

While I'm puzzling about those machines, I also note that Felder's spec about the filters doesn't tell the whole story. They say the output dust is .1 mg/cubic meter. For the safety of users' lungs, the big issue is how much extremely fine dust is exhausted. They're not saying how big the dust particles are, and that's a problem.

[Bill Dufour]

I don't know much about them but my father had a one HP cyclone blower for a organ. It ran the pipes and various bellows to ring bells, bang a drum etc. It made good airflow and had to be quiet. Different impeller styles make more noise then others. For dc the concern is handling chips that sneak through without clogging. Noise is far down the list well after suction and exhaust pressure and cfm. I bet efficiency is a concern for big shop size multi horse power units running 8 hours a day.
Bill D.

Some mention of noise issue here:

http://hardmanwurlitzer.com/blower/

[Matthew Hills]

Felder sure is close-mouthed about those dust collectors. They don't seem to be cyclones. As far as I can tell, they just have big filters, with the blower sucking air through them. I'm guessing they have some sort of cleaning system to knock the dust off the filters.

While I'm puzzling about those machines, I also note that Felder's spec about the filters doesn't tell the whole story. They say the output dust is .1 mg/cubic meter. For the safety of users' lungs, the big issue is how much extremely fine dust is exhausted. They're not saying how big the dust particles are, and that's a problem.

By all accounts, the filtration on the RL series is supposed to be quite good and they can be a good choice if ceiling height is limited such that no room for a full-height vacuum. You will also see some people post issues with them--worthwhile to do a search and compare among the various options.

There are several different designs in the RL series -- some of the larger collectors run an internal bag-house style filter that can be cleaned with air puffers, but there isn't an option for a filter cleaner on the smaller models.

I saw an early promotional article on the RL-125/-160 that show the construction about the design:
Cleaner than claen-air, dust extractors! (http://fpartner2009.felder-group.com/files/testreport/tsr_pdf_240_1_703.pdf)by John Renzetti

Folks going in to replace the filter sometimes post photos of the guts of the system.

Matt

[Dan Friedrichs]

Bill, you sent me down a rabbit hole of reading about pipe organs for more time than I'd care to admit :D That is really cool! Wonder how that guy has the time (or money) for such a crazy endeavor...


I guess I was just curious if there was something specific to these "euro" dust collectors that causes them to be more quiet (e.g. do they use a different type of blower since the dirty air doesn't touch the blower? Do they run slower motors? etc)

[Wes Grass]

I briefly looked into the RL-125. The price was ... well ...

Bigger issue for me was the floorspace it uses up.

It has a system to scrub the filters, IIRC. Manually operated. The handle is above the inlet, which makes it a no-go if you want to run the ductwork straight to the ceiling.

[Patrick Walsh]

I have a rl 125.

I don’t know why it’s more quiet or that it really is honestly. I have years of experience standing next to various dust collectors all day long at this point. Pretty much all the big brand names. Pretty much my Felder even with a silencer is just as loud.

The filters clog like crazy. There’s a manual brush that indexes a pleated filter that you push back and forth “pretty much everytime you turn it on” or you end up regretting it. Even adjusted well “brush to filter” it does a poor job as dust just gets jammed deep up in the floats of the filters and no brush is ever cleaning them that deep in the pleats.

Plus the gasket around this giant very expensive filter blows off from the suction of the machine on average well all the dam time.

To clean the filter you have to take it outside and bang it out carefully and it makes a huge huge huge mess. Compressed air worked but Felder saiz don’t do that. I have had the same issue with Oneida filters when you overflow them. But this same thing happens to the Felder even without overflowing it or not emptying it soon enough.

The floor space at least for me is and was my driving force and then the claim if those German clean air standards. Those clean air standard go right out the windows when you figure out that gasket even when not blown off always leaks a bit.

All dust collectors stink but this one stinks and it twice the price and requires expensive bags. Reuse the bags with a slight hole and forget about clean air.

If I had the height I’d just buy an Oneida. I use a clear view at work and it seems kinda like a toy to me. Same as Oneida really but at least a big Oneida feels like a real industrial machine. The clear view seems like a woodpecker square vrs a just good high quality macchiato square. Don’t like woodpecker either as I have had a number of their squares that did not end up being even close to square.

To be clear the RL is ok when it works as it’s kinda fancy looking. The barel on wheels is nice and I don’t know other than that it’s a waste.

[Dan Friedrichs]

Thanks, Patrick - I knew about your troubles with your RL-125, and that's what got me looking at the Al-Ko units. I've read they are extraordinarily quiet, and I'm wondering if that's just from "normal" sound dampening techniques.

[Patrick Walsh]

Ah I missed that your question or motivation is toward the Al-ok units,

I thought you were asking about the Felder units.

I guess I’d consider the Al-Ko also if I really thought it would be everything I thought the Felder would be vrs or over a onieda. And who knows maybe they are.

But with the high price I’d want to know exactly how they differ if AL-Ko is making the Felder units.

And I now suspect and get that’s probably what your trying to figure out. Sorry I’m often late to the party.

I’m pretty smart but it sometimes takes me a bit to get up to full operetta game speed. I’m kinda half blond and pretty sharp all at the same time.


Thanks, Patrick - I knew about your troubles with your RL-125, and that's what got me looking at the Al-Ko units. I've read they are extraordinarily quiet, and I'm wondering if that's just from "normal" sound dampening techniques.

[Bill Dufour]

Moffet field near San Jose California has a big wind tunnel. Four motors of 65,000 horsepower for a total of 260,000 Horsepower. I bet it is loud. speed is up to mach 3.5. No mention of airflow or filtering.
Bill D.

https://en.wikipedia.org/wiki/Unitary_Plan_Wind_Tunnel_(Mountain_View,_Californi a)#Drive_system

[Wes Grass]

Tour of SLAC many years ago, they told us they couldn't run the accelerator at the same time Ames was running the wind tunnel. Not enough capacity on the grid.