The Official Mercdog Flowbench thread - The Official Mercdog Flowbench thread

[Thomas Vaught]

I am looking at using a aluminum flow orifice disc with a 8" diameter that I can drop into the bench
from the outside either with a large port hole or a removable plate. For exhaust flow I would just flip the disc over. Different 8" discs would have different orifices.

Tom V.

[Fkned]

John,how does your flow element work?Is there a way to replace the orifice disk w/it in the Mercdog bench?

[turbotuner]

Ok I'm a little confused about the Manometer setup on the Mercdog plans, figured it made more sense to post it here then to start another thread. It seems the plans/bench is setup to test pieces at 28" water, but the length of the inclined scale is 28", not the rise. So if you install the Manometer at 26* like the plans state, it works out to be about a 12.4" rise. After reading through the old forums last night until my eyes bugged out, I am under the impression that if you want to test pieces at 28", then the vertical rise of your incline scale must be 28" which means that at 26* then the actual lenght of the scale (hypoteneuse of the triangle) would need to be around 62". I totally understand the square scale, this is the only piece of the puzzle I cant quite grasp. So am I missing something, or would I be right to redo the incline to get my 28" rise?

[Mouse]

[mdavidsn]

John,

What is the cfm range that your flow element will measure?

Mark

[Mouse]

[turbotuner]

[Pesty]

John, you posted a diagram showing how the FP1 is attached to your FP FE2.5, at the bottom is there a reducer connected from the pipe coming out of the FE 2.5 to the 4" abs pipe??

Pesty ???

[Mouse]

Hi Pesty,

Yes, a 4" to 2" reducing bushing (available from your hardware store). What I do is bore out the 2" slip area so that the flow element can simply slide in and out very easy without leaking too much air. That way it can be slid down a bit to remove it from the receptacle.

It doesn't show it, but the 4" or 3" pipe is actually a loop made from 2 Ys. The element actually fits into one of the Ys. Using Ys in a loop configuration provide a superior velocity profile into or out of your element or recptacle (settling chamber). A piece of sheet plastic is glued to the bottom of the Ys to keep the air straight and from swirling in that area of the Y. Also, the feed Y (into element/receptacle) is not glued into the loop, so that it can pivot or tilt to aid in removal of element or connecting pipe.


John

[Thomas Vaught]

Can you post a pic or a diagram John?

Tom V.

[Mouse]

This picture shows a 3" loop with a Flow Performance FE2.0m flow element.


This picture shows how the 3" feed Y can tilt for removale of flow element. The element is pushed down into the Y to clear the receptacle above, then tilted to remove.

This bench is good for 360 SCFM @ 28"wc using 4 of the #16-1234 motors from Surpluscenter.com.

[Thomas Vaught]

Thanks
Tom V.

[Pesty]

John, i was thinking over the items you posted and thought about the y piece in a different manner. By placing the flow control valves as close as possible to the y piece. My only concern is the turbulence at the y piece??? and would it be detrimental. Now after seeing your reply, i think that may be a better option, as with anything to do with flow you want the smoothest transition without causing interruptions..

???

[Pesty]

John, Further to my last reply, you said a piece of plastic is placed in the y piece to prevent swirling, this is what they actually do to the base of intake manifolds to aid in fuel delivery to each cylinder just below the carb base. It actually looks similar to the shape of the manual kitchen juice extractor. I remember seeing it a circle track or one of my hundreds of books.

"Innovation is only limited to ones vision"

[Mouse]

Pesty,

The possible problem encountered with an elbow into the flow element is an uneven or biased velocity profile through the element. This may become evident when a test piece is flowed in 2 different positions, perhaps if rotated 180 degrees, and is usually noted in exhaust mode where the flow element is directing the air at a particular area on your test piece.

Local air turbulence is not a problem if given enough straight run to settle it. The Flow Performance FE2.0m flow element is especially good at handling a certain level of turbulence through it's unique design, but the problem, again, is what happens to the air in the receptacle or settling chamber.

I have been working on a air source box that hopefully minimizes the complexety of air flow reversal into a pipe. There is a diagram of it somewhere on this site, maybe this thread, I can't remember. Basicly, the box is able to slide so that it's intake or exhaust ports can be positioned line up to one pipe.

John