Thread: Oneida super dust deputy kits

Originally Posted by QC Inspector

It would be far more useful if they just stated the static pressure loss with the airflow they tested.

Agreed. That's what I asked them for.

Originally Posted by QC Inspector

Oneida's "equivalent" is a touch vague but using a duct loss calculator for 5" hose and 550CFM (max 5" duct can flow) exposed hose has a static loss of 1.283" and the covered hose has .843". It would be far more useful if they just stated the static pressure loss with the airflow they tested. That is why I am curious what a test done on one would show. At the moment only Oneida knows for sure.

Bill stated his design has a static pressure loss of 2.25". It would be harder to verify that because the impeller and cyclone are integrated as unit where the Dust Deputy is separate and can be tested with and without for the resulting difference.

Clear Vue used to publish the fan curve for their cyclones but don't anymore. I presume because it prompts comparisons to others that claim higher flows without showing their fan curve.

Pete

Originally Posted by jack620

Agreed. That's what I asked them for.

If I were Oneida I would use the exposed hose for the comparison because that gives the shortest equivalent length, So, 1.283".

Based on testing that jack620 did my number crunching yields 15' equivalent hose length. Using the same online calculator 15' of covered hose results in 1.265" pressure loss.

So those numbers are in really good agreement. Now, since 550 CFM is just about a 1" velocity pressure (it's NOT a maximum, just a convenience) I would just round that up a bit and call it a loss coefficient of 1.3.

By the way, the loss coefficient of that separator/bag holder thing is about 2.1 so getting rid of it and replacing it with a DD will actually improve the flow.

Originally Posted by dmorse

By the way, the loss coefficient of that separator/bag holder thing is about 2.1 so getting rid of it and replacing it with a DD will actually improve the flow.

That was certainly my experience.

Originally Posted by jack620

Onieda told me the 5" SDD is equivalent to a 10ft length of 5" flexi.



I've never seen any airflow measurements for the Clearvue either.

Contrary to popular opinion measuring air flow is a moving target for all sorts of reasons and any flow figures from any manufacturer will be quoted at 60hz and not 50 due to the prime market being the US. None of the manufacturers quote installed figures thus any figure you see is not installed and it can be discounted about 30% for 50hz operation. Clearvue in particular recognise that quoting numbers will cause them to justify that number and in reality no one can do that due to variations in the installation or even in the measument of them because there is no standard to measure against. For iinstance even hot air v's cold air will get a different result due to density changes.

Originally Posted by Chris Parks

Contrary to popular opinion measuring air flow is a moving target for all sorts of reasons and any flow figures from any manufacturer will be quoted at 60hz and not 50 due to the prime market being the US. None of the manufacturers quote installed figures thus any figure you see is not installed and it can be discounted about 30% for 50hz operation. Clearvue in particular recognise that quoting numbers will cause them to justify that number and in reality no one can do that due to variations in the installation or even in the measument of them because there is no standard to measure against. For iinstance even hot air v's cold air will get a different result due to density changes.

Chris, it's not really all that difficult. Nobody is asking for as-installed performance. That would be absurd. There are standards for measuring and presenting performance data. In the US Oneida, Grizzly, and Laguna all provide performance curves for their cyclone based dust collectors. My guess for the reason Clearview doesn't is simply that their market doesn't demand it. If people buy your product as-is, why add the expense of testing?

The effects of frequency and air densty on performance are quite predictable. Any good HVAC technician knows how to make those corrections.

Dave, fan curves can be supplied but that is not the air flow number when the impeller is installed. I do not know of a standard to test an assembled dust extractor but I am not saying it could not be done only that as far as I know no one has bothered. I can understand why it has not been done and that is it would make a nonsense out of quoted performance figures that have been quoted up until now. Bob has demonstrated more than once how difficult it is to meaure the performance of a DE and a duct connected to the DE.

Re-reading your post I hope we are not talking at cross purposes. Oneida can quote what they like but until every manufacturer is using the same standard it means very little.

Originally Posted by Chris Parks

Dave, fan curves can be supplied but that is not the air flow number when the impeller is installed.

I can't make sense of that statement. What kind of fan curve do you get without an impeller?

I do not know of a standard to test an assembled dust extractor but I am not saying it could not be done only that as far as I know no one has bothered

Testing is done by treating the DC as a fan and testing with a simplified version of Figure 16 from ANSI/AMCA 210.
Example:
G0852.jpg

With that and a calculated system curve for your ducting you can then estimate your installed flow rate.

Another example:
CFlux3.jpg

This has gotten a bit off topic with discussion of line frequency and dust collectors. Back to just cyclone bodies:

The pressure drop of a cyclone can be characterized by a single dimensionless number. For cyclones the Euler number is often used and relates the pressure drop from inlet to outlet reference to the velocity pressure inside the cyclone. Another number that can be used is the loss coefficient and it relates the energy loss to the inlet velocity pressure. A close relative of loss coefficient is discharge coefficient. All of these are nearly independent of flow rate and scale factor, depending almost entirely upon the geometry of the system.

A cyclone manufacturer should be able to provide that information. It's fundamental to cyclone specification.