Dust Collector or Dust Pump?

[Ken Ganshirt]

I posted a couple of messages with graphs and comments in the original Dylos particle counter thread. During the testing I had come to the conclusion that my dust collector was actually working as a pretty good air cleaner.

I have the Dylos 0.5/5 micron particle counter.

The dust collector is a little 1HP King with a 1 micron top bag and poly bottom bag. I have added closed-cell weather-stripping around the top and bottom of the bag tree so I have a pretty good seal for both bags. I noted during the testing that I could leave the dust collector running with the flex hose laying open on the floor for a couple of hours after machine operations and it would pull the fine particle count down into the low double digits .. typically 20 to 30 on the metre display.

I've been struggling for the past few years trying to figure out what to do about improving my dust collection in the shop. I have known for a long time that my 1HP DC - bought when I started woodworking a few years ago and knew little about woodworking and nothing about dust control - is not the answer. So, what to do? ... Well, for me the question is what to do that gets me the most effective dust control for the least cost?

I've done all the reading on Bill Pentz's site and a variety of other sources, including multiple woodworking forums. I've achieved a pretty good understanding of what I need to accomplish it. Until I got the Dylos particle counter I never had any way of determining how bad my current setup might be nor any way to tell if any changes I made were going to be effective or a waste of money.

While I was muddling around trying to figure out what do to I decided the best interim solution was a good respirator so I got a Trend Airshield a couple of years ago. It works well. So my goal became somewhat modified. While I'm machining and wearing the Airshield I really don't much care how much dust gets in the air.

So the goal became, after I shut the machines off how quickly can I get the fine dust content back down to a level that allows me to take off the respirator and work without it?

I thought my testing with my little dust collector had given me the answer .. get a single stage dust collector with 1 micron bag and better airflow to capture more of the fine dust at the source and cycle the shop air through faster after the machines are turned off so the fine dust count comes down quicker than with my little 1HP DC.

All of my research over the past couple of years indicated that the Delta 1½HP was at the top of the list for single stage dust collectors. So when it came on sale here a couple of weeks ago I bought one.

I've done a little measuring since I got it assembled and I must admit to some puzzlement at the results. Unlike my King 1HP with the 1 micron bag, which seems to be a great air cleaner, the Delta seems to be a major dust pump.

As an example, I was doing some turning yesterday. I'm using dry lumber so even with a sharp gouge there's some dust created. I'm a novice turner so I tend to rely on my scrapers a lot, which create a little more dust. I've got a piece of flex hose near the lath to suck off the dust and any shavings that get near it. That Delta 1½HP unit sure grabs the dust away from the lathe area nicely but it seems to just blow it right back into the air.

Doing this sort of operation with the 1HP collector running seemed to keep the fine particle count down below 500 on the metre display. With the Delta hooked up and running while I did the same thing, the fine particle count got up above 4500 on the metre display fairly quickly and stayed up there. Stopping the operation and leaving the Delta run for an hour made no difference. Turning off the Delta, turning on the King and leaving it run for an hour made a big difference .. pulled the fine particle count down to under 500 in an hour or so. Leaving it run for a little over 3 hours had the fine particle count down to 8 (yep, that's right, EIGHT).

So, what's going on here????

The only thing I can think of is that the 1 micron bag on the 1HP King has a pretty good cake built up in it and the Delta 1½HP has a fresh clean bag so the bag on the King is filtering the fine particles and the Delta is just recirculating them.

Does that make sense?

...ken...

[Phil Thien]

The only thing I can think of is that the 1 micron bag on the 1HP King has a pretty good cake built up in it and the Delta 1½HP has a fresh clean bag so the bag on the King is filtering the fine particles and the Delta is just recirculating them.

Does that make sense?

...ken...

I suspect you're correct. But there is only one way to find out...

Unless, of course, someone else has the Dylos w/ the same DC and can report their observations.

Also, are you sure there aren't any leaks on the Delta?

[Leo Graywacz]

Why don't you get an air cleaner. I have the JDS 750 and it works well. Much more efficient than letting your dust collector with a 4" intake run for 8 hours. But if your DC is spewing dust into the air instead of capturing it, you need to look at solving that problem too.

[Steve knight]

a big part of what your seeing is the amount of air your moving has changed. Your little guy did not move a lot of air so it could not force much dust through the bag. going to a more powerful blower allows more dust to be blown through the bag. the dust cake is some of it but the bigger blower is the biggest problem.
the solution to this of course is bigger and better bags. most if not all single stage units loose a lot of airflow because of the small bags they need to have. plus because of that a lot of fine dust will blow through them no matter how fine they are.

[Dave MacArthur]

Ken, you came to the same conclusion I was going to say--dust cake. I have the 50-760 also. I recall reading that the 1 micron bag on it didn't really give the "rated" filtering until it had a decent dust cake on it, by which time the CFM was much reduced.

[Ken Ganshirt]

Leo,

In fairness I didn't make clear that my goal for dust collection/control is to save my lungs. If all I cared about was shop cleanliness I wouldn't have a problem to discuss. My 1HP King DC and my two shop vacuums do that job perfectly well. The dust collector does a fine job of chip collection. The shop vacuums, with their HEPA filters, do a great job of vacuuming up the rest of the junk without recirculating anything they suck in.

I don't get an air cleaner because I haven't yet found one with filters better (smaller) than 1 micron. The particles of most concern are those smaller than 1 micron. Since my main goal is to protect my lungs, I view an air cleaner that simply recirculates the finest particles as a complete waste of money for me. Others will have different goals and so will make different decisions.

I'm not entirely certain how an air cleaner would be "more efficient" than running my dust collector for a given period of time (not eight hours, by the way). Let me ask the question this way: if I could find an air cleaner that would filter the fine stuff as well as my King dust collector does right now and if it had the same airflow as my dust collector, in what way would it be more efficient to run the air cleaner instead of the dust collector?

If I can find or build an air cleaner that effectively filters the particles of most concern to me, I will buy or build one. I am presently looking for a Canadian source for one of those big Wynn 0.5 micron pleated filters that some of the cyclone guys are using - or better still, one that size with HEPA rating - so I can build my own air cleaner around it.

Steve,

That's an interesting thought about the increased airflow versus the airflow capacity of the filter bag. I don't think it's the size of the filter bag on the Delta at this point. When I turn the Delta on, the bag does not fill. It has almost no tension on the surface at all, which tells me that the airflow is almost totally unrestricted by the bag. That's backed up by my initial current draw testing. As I assembled the dust collector I decided to get some baseline current draw numbers. Before adding the bags I did a test with the dust collector intake and outlet wide open .. nothing on the bag tree and nothing on the 5" intake (the reading was 15.1A). Then I installed the bags but still nothing on the 5" intake. The reading was still 15.1A.

That tells me that the filter bag is presently flowing as much air as the impellor can shove through it, yes?

The filter bag on the King, on the other hand, fills like a baloon. That suggests that it has become somewhat restricted. The downside being that it's probably not flowing as much air as it's capable of. The upside being, of course, that most of the fine stuff that's getting sucked in is staying in.

Phil,

At this point I have absolutely no idea how I would test for leaks on the Delta other than visual and tactile examination, which I've already done. The Delta has a really nifty method of securing the bags to the bag tree. There does not appear to be any way to have a leaky fit on the filter bag and the poly bottom bag also seems to be secured quite well.

Any thoughts on how to test for leaks - short of sucking a few pounds of my wife's bread flour into it!! - would be welcome.

...ken...