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Thread: How to measure dust collector performance.

  1. #31
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    Quote Originally Posted by Paul Stoops View Post
    This may sound a little wacky, but could you post a pic of your wiring in the J-box? Maybe we could figure out how to reverse the direction of the motor for a test. I am not familiar with curved bladed impellers, so I don't know which way it should rotate.
    The rotation is correct if the drawing is correct. Most blades on DC impellers bend the other direction. HF to my knowledge is the only one using a forward curved blade. They deliver more cfm at lower pressure but generally are not as desireable at working pressures. I don't why they do what they do. Dave

  2. #32
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    Yes, I think you measure the difference between the height of the liquid on each side.
    From Bill Pentz's site:
    "This test measures the vacuum
    that "pulls" the air through the tube so the water on the side of the gauge
    gets pulled up causing the water on the other side to go down. Do not
    measure the water height from the center, measure from both ends of the
    water column.
    This Max. SP should be the highest pressure you will ever
    see from the blower.

    If you are actually seeing 6" WC, that is probably okay, considering your altitude -- as they say,"Bigger is better" in this case.

  3. #33
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    OK. So this is where I am at now.

    Thanks to David, I now know the DC is turning in the right direction.

    I also know that I am actually measuring 6” WC thanks to Michael and Paul, and the 3” WC was pilot error (I was the pilot).

    The only question left to answer is why I am pulling only 8.5 amps at full load, and I will check into that. I guess that will be either pilot error again, or the altitude really affects the load on the impeller.

    Thanks to everyone for helping me understand this better.

  4. #34
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    Any idea what the FLA rating is for your motor?

  5. #35
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    Well, the specs say it is a 20 amp motor, but most of the threads I have read say that it starts at about 20 amps and then immediately drops to about 14-15 amps. This is under a load, meaning that at least one blast gate is open. I assume that with no gates open it would run at about 7-10 amps.

    I am now considering that my problems, including the low amp draw, could be because the impeller is just too small for my altitude. This seems to be pretty well known to some of the experts, as they recommend a larger impeller for higher altitudes.

    Wish I could just add a slightly bigger impeller to mine as it looks like it could hold a 12" (has a 10" now).
    Last edited by Vaughn Kaloust; 03-13-2013 at 10:09 PM.

  6. #36
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    10" is too small to pull much cfm at pressure. Since the altitude also allows for a lower hp motor- correction is 1.2 also- you could use a 12". I would get the blades bent in the other direction or a straight blade impeller. Almost any impeller with the correct sized arbor should work. most housings are reversable so you can correct for the blade configuration. Dave

  7. #37
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    Wow, thanks Dave. I have been searching the net to see what I could find, but all I have found were blades that are straight and I thought that wouldn't work.

    So just to see if I have this right, you are saying that I should be able to use a straight blade, 12" impeller? And it obviously needs to fit in the housing and on the shaft. I think Jet has one that will work. I think if I can get to 12" it will draw a more appropriate amount of amps. and improve CFM dramatically!

    Any other recommendations?

  8. #38
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    Vaughn
    Take a look at this link.
    http://www.cincinnatifan.com/catalog...1-internet.pdf

    On page 5, there is a good explanation on how to use the tables at different densities. If you go through the example, this will give you a good insight on the effects of density and fan selection. You and David are correct that a larger fan and/or higher RPM is needed at lower densities to move the same volume. However, the HP requirement goes down as apposed to operating at standard conditions.

    There is also a picture of a typical BC fan wheel which is opposite your HF wheel. You may be able to order a wheel from Cincinnati Fan if you are interested in a replacement. I think there was a thread on here several months ago where someone reversed the rotational direction of their HF wheel and saw a significant increase in motor amps (increased volume)?

    Mike

  9. #39
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    Vaughn, three things to expect with a straight blade impeller.

    1. It will be loud. Like an airplane
    2. It will pull more cfm when hooked to pipe and flex but less with no restriction
    3. It will pull more amps. Should be no problem but to be safe you want to check the amp draw closed and then open one gate and check. Finally all open to make sure you are not exceeding FLA. If by chance you are you just can't run it with all gates open. I don't believe you will have a problem at that altitude and the straight blades may be a help at that altitude.

    Any Grizzly, Asian fan should work. Dave

  10. #40
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    Dec 2012
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    Mike and Dave, thanks for all the effort.

    Mike, really good info. I may give them a call tomorrow, but looks like they may be high dollar,but you never know.

    Dave,
    1) NP as I am nearly deaf already. I do wear ear protection in the shop.
    2) Good! I only need the CFM when I am connected to the ducting, so that works perfectly.
    3) I will follow these directions to the letter. And Paul already sent me a PM where he showed me his setup for monitoring amperage, and I will get that hooked up before I start testing.

    This forum has been so helpful to me today. Thanks to all.

  11. #41
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    I find the Cincinnati fan tables so useful I printed them out for several models. Ebay and CL are good sources for stand alone blowers. I bought a 7.5 hp CF RBE9 for $600 that included a Baldor motor. Smaller ones can go pretty cheap. If you have the CF brochures you can watch for the right one. Dave

  12. #42
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    Quote Originally Posted by Vaughn Kaloust View Post
    ...Paul already sent me a PM where he showed me his setup for monitoring amperage, and I will get that hooked up before I start testing.
    I'm interested in some ideas on monitoring fan current. All the handy "Killawatt"-like devices I've seen are 120V only. 240V ones on eBay that I saw all had european round pins on the back. Also on the 'Bay I found this cheap ($15) idea:



    search "240V amp meter"

    I'm considering building this into my contactor box if there's room.
    Any other ideas?

  13. #43
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    Quote Originally Posted by Mark Burnette View Post
    I'm interested in some ideas on monitoring fan current. All the handy "Killawatt"-like devices I've seen are 120V only. 240V ones on eBay that I saw all had european round pins on the back. Also on the 'Bay I found this cheap ($15) idea:



    search "240V amp meter"

    I'm considering building this into my contactor box if there's room.
    Any other ideas?
    I'm going to give one of these a try, too. You might want to search for item #310604994957 on the bay, exact same meter for $8.99 shipped. For 9 bucks it's worth giving it a shot.

  14. #44
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    Quote Originally Posted by John Lanciani View Post
    I'm going to give one of these a try, too. You might want to search for item #310604994957 on the bay, exact same meter for $8.99 shipped. For 9 bucks it's worth giving it a shot.
    I have seen generator hookup panels with this basic setup. I had a grizzly drum sander that had an ammeter... I wonder if you could purchase these components as if they were a replacement part? (should already be calibrated that way)

    Edit: just took a look and this one has the pickup included

    http://www.ebay.com/itm/Digital-AC-3...81004140330%26
    Last edited by Carl Beckett; 03-14-2013 at 7:10 PM.

  15. #45
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    Quote Originally Posted by Carl Beckett View Post
    I have seen generator hookup panels with this basic setup. I had a grizzly drum sander that had an ammeter... I wonder if you could purchase these components as if they were a replacement part? (should already be calibrated that way)

    Edit: just took a look and this one has the pickup included

    http://www.ebay.com/itm/Digital-AC-3...81004140330%26

    The one I referenced includes the current transformer too. I'm going to incorperate it into my drum sander, I'll keep you posted.

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