Lost suction!!! Please help.

[painterman]

Last week I did two things.  The first was to get my 4 inch flex hose off of the ground.  I had two 4 inch flex coming from two trunks of 4 inch pvc.  They just laid on the ground and I was tired of cleaning around them and tripping over them.  So I went to the ceiling and other means.  So I basically added about thirty feet of more pipe/flex with more turns and angles.  I am not sure how much it affected the suction because I was busy making my Thein separator and wasn't paying attention.  So then I built the separator as pictured and then noticed that my suction dropped off quite a bit.  I have a grizzley 1029, 1180 cfm and five inch inlet and outlet.  All my pipe is 4 inch pvc and 4 inch flex. Here is my questions
- how much suction loss is because of the separator
- how much suction loss is because of my basic 4 inch setup with flex connecting the machines, connecting trunks, and the DC.
- if I was to get a bigger machine, say a 1550 cfm or 1700 cfm with running 6 inch  everywhere that I can, would I be back to where I was before last week.  (still using the separator) (by the way the separator works fantastic with sucking over 17 gallons of saw dust during testing and only having about half a cup of fines in the bag).
I know this is all hard to say, but I am willing to buy a newer bigger machine and run bigger pipe if it will make a difference.  It seems that when I put the separator on that I lost a lot of suction.  Is there a way to make the separator more efficient?  My slot is about 1 5/8 inches wide.  Is that to wide? Does it matter?
Sorry about these crazy questions.  Just confused.
I need more suction but want to keep the separator.

Please, any info would help.
Jon

[painterman]

hi chuck thank you for responding .  my grizzly 1029 is an older version and the intake is  5 inches.
how much does having the separator affect the pressure loss ?   I do plan on upgrading my machine and also all of piping  to 6 inches far as I can. what do people find out after they add the separator as  to the pressure loss ?
thanks jon

[painterman]

If I do go for a new machine with a 6 inch intake and keep 6 inch trunks as far as I can, wouldn't I be far better off than my machine with 5 inch trunks?  Or is it not worth it?  I noticed at Lowes that the metal is 30 gage and not the recommended 26 gage, but also noticed that the crimping is all going the wrong way for dust collection.  How do people deal with that?  Thanks in advance.

Jon

[Bulldog8]

Painterman, if you are still looking for 26 gauge pipe, check out a HVAC supplier. I ordered my pipe from PSI and later found that I could have gotten it down the street for a similar price and wouldn't have had to pay shipping.

Pitbull has piped his system with 30 gauge and reports good results.

My system is powered with a Griz 1029 that has a 6" intake. I had a duct system made of 4" PVC and flex off of the griz. When I built the Thien baffle, I upgraded to a Wynn filter and 6" mains at the same time. I ended up with a significant increase in air flow and suction.

I see that your system has flex all the way to the baffle. If you are going to re-pipe, I would consider making the last section as straight as possible. I think that the main run right before the separator is the place where you want the highest possible debris speed to get the maximum separation.

I have found that the lower plastic bag on my DC gets no dust or chips. This is after filling the separator barrel several times. I have gone to the point of closing the bottom of the chamber and running a filter on top with a plastic bag closed inside of the bottom chamber to be used for filter cleaning. There was a significant reduction in noise by doing this.

In the pictures you posted it looks like there are chips and dust in your plastic bag. This leads me to conclude that you are not moving enough air to make the separator work as well as it could.

Steve

[painterman]

Once again thanks to everyone for your help.  Steve, my "clear" bag is difficult to see through but there really is no chips in the bag and very little fines.  I didn't quite understand what you did with your lower bag.  Do you have a bag at all?  Could you describe again?  And how would that lower the sound?  Thanks, Jon

[painterman]

Chuck, thank you for your help.  I have gone back and forth between metal and pvc.  My thinking was that pvc was smoother on the turns, so maybe was "better".  But when it gets down to it does it make that big of difference?  Does the crimped side of the metal narrow the pipe a bit?  Once again, does it really matter?  I only want to do this once more and would like to do it as right as possible.  I found a good supplier for 26 gage pipe right here in town and they can even supply me with none crimped metal (to give me a choice).  Some one please sell me on using metal or pvc.  The internet is full of both sides, but I tend to favor the opinions of those on this forum.

Thanks,
Jon

[painterman]

I forgot, one last question.  Is 26 gage metal y's strong enough to have a gate (being pushed and pulled on) and have a 6 inch flex hose hanging off it?  Does it move, bend, or otherwise not be strong enough to survive my shop.
Thanks again everyone
Jon

[Bulldog8]

Painterman, after I upgraded to a Wynn filter, I found that my DC was quite a bit louder than it had been with bags and PVC pipe. This was due to the larger amount of air and its speed. I considered buying or building a muffler that would fit between the blower and the filter, but hadn't got around to it yet.

I saw another post when a guy was thinking about building a dust drawer to collect fines when cleaning out the filter. Because my plastic bag wasn't really doing anything expect catching fines when blowing the filter down, this sounded like a good idea to me. Last weekend I was out in the shop and looked at the lid that came on my drum, it looked about the same size as the bottom of my DC ring. I checked to see if it would or could serve as a temporary dust drawer.

It fit, and I found when I turned the DC on, it was a lot quieter. Knowing that I wanted to be able to catch all of the fines when cleaning the filter I folded a bag in half so that it was only half as tall as normal. I secured this in place with the clamp and sealed with tape. Here is what it looks like.



I then folded it up and put the drum lid back on as a cap.






So all in all its a lot quieter and takes up less space.

I did a short video to show the difference in sound. The camera doesn't quite do the sound justice, but here it is.


http://www.youtube.com/watch?v=L-x9fZpAsa0

[painterman]

Thanks, Bulldog.  That video was great.  So do you think that most of the noise comes out of the bag area?  And if you built a little enclosure around the bag, would that help with the sound.  With your system, do the fines keep recirculating and never fall down or do you have to empty more often?  I could go for less sound.  Thanks for the explanation and video.  You have my mind a going
Thanks,
Jon

[Bulldog8]

Are you asking about fines in the bag or the separator? I don't get anything at all in the plastic bag. I have filled the separator barrel to the point where debris was swirling in the chamber and couldn't go down due to the sawdust level touching the bottom of the drop slot on the size opposite the inlet. Even then I didn't get chips in the plastic bag. I assume that I would have or could have collected more fines in the filter by filling the drum so full.

I don't routinely clean my filter unless I had used the drum sander a lot. I make end grain cutting boards which require a lot of sanding and get a lot of dust. When I am done with the sander, I blow the filter down and let the dust settle in the bag for removal.

In you discussion you also asked about 26 gauge Y's. I used pipe and Y's from PSI, they were their lower cost sets. For the drops I used their package that they called an "economy" drop. It had the Y, blast gate, clamps, flex pipe and a straight pipe. I have 10' walls in the shop so the drop kit didn't drop the blast gate as low as I wanted, so I added a piece of PVC to get things where I wanted them. Here is a shot down the main run.

I still have to replace the right hand main run with metal.



Steve

[painterman]

Hey everyone, I finally had some time to do some "testing" on my new top hat design.  My top hat dimensions are as thus:
overall diameter is 2 feet
inside diameter is about 21 inches
inside height is 6 inches
fall through slot is 1 3/8 inches
thickness of baffle 3/4 inch
intake size 5 inch (with 4 inch attached to it)
exhaust size 5 inch

I took off the inlet hose to the impeller, turned on the DC and felt the force of the suction at the impeller intake.  It is quite strong.  then I put the hose back on between the top hat and impeller intake and felt the suction at the top hat intake.  It seemed like quite a bit less than at the impeller intake.  Like maybe even half.  Obviously this is hard to quantify, but my son and I both thought that is was quite a bit less.  So my question is:  Is my design at fault or is this the normal loss of suction in these designs?  I checked for leaks and did not find any.  I am not sure this is acceptable now.  Is there any changes I can make to the top hat to reduce the loss?  Please refer to the top of the thread for pics.  Thank you in advance.
John

[Vodkaman]

My stab at an explanation would be, that you are not feeling the full power of the vacuum with your hand at the top hat inlet. This is because the plastic bin under the top hat is flexing and absorbing some of the power or energy. Under normal conditions, the bin won't flex and your system will work fine.

To test this theory, place a layer of polythene sheet between the bin and the top hat assembly. This will cut out the bin flexing effect. Now repeat the hand test.

Dave

[bill70j]

Painterman:
To answer your question about the losses through a separation system.  They can be huge, depending on flow.  At max flow they can be as large as 60% of the unit?s capacity.  And that is what you are feeling with your hand testing.  But under normal conditions, they are probably closer to 10 ? 15% of total capacity.  I agree with others that your issues are likely not with your top hat system.

Here is my experience with separator losses.  I built a trash can separator for my Harbor Freight 2HP unit and measured the actual vacuum at two locations with a gage, just like you did with your hands.  You can see from the images below, that at the separator inlet under no load, the vacuum was 1.75" of W.C, but at the blower inlet under the same conditions, it was 6.0" of W.C.  So at maximum flow conditions, the loss through the can was 4.25" or almost 60% of the total capacity of the unit (which is about 7.3? of W.C.).  I did smoke testing on my unit, so know there are no leaks and the losses are real. 

The reasons for my losses are due to the friction loss through two 90deg elbows, the 45deg wye, plus other friction losses from the air moving from the can back into the blower suction pipe.  Wood Magazine just did an article on calculating losses in a DC system under normal conditions (350 CFM).  If I use their spreadsheet, I come up with a predicted loss for my separator system of 1.05? of W.C.  But that is at normal flow conditions.  At max flow conditions for my unit of about 650 CFM, that figure translates to 3.62? of W.C. which is not too far from the 4.25? I measured.

In Wood Magazine?s 3/2008 article, they show your Grizzley1029 as having  something like 900 ? 1100 CFM capacity at max flow conditions and a max static pressure of 9? of W.C. ? far superior to my HF unit.  So you will see even larger differences of loss between max and normal flow conditions.

[pitbull]

John-

First thing...go with 6" metal pipe. End of duscussion (PVC is not any cheaper, and it is much heavier, and it carries static). You can use 30 gauge no problem or go thicker if you prefer.

Second, sell your current grizzly dust collector on craigslist and pic up a newer used model that has a 6" inlet

Third, unless your place in town can compete with these prices... http://www.kencraftcompany.com/Dustindex.htm I recommend this company. I used them for all my wyes and blast gates and shipping was actual charge..no fluff/ no tax.

Forth- Limit flex hose to as small lengths as possible and round your bends so they are not a true 90.

This will all considerably increase your CFM and it will be night and day.

[pitbull]

Bulldog-

Nice move with your noisy bag. I am going to check that out for sure-