Initial Test Results

[Dom G]

Sorry, I know there's a way to add multiple pictures I just don't how to do it. This is the last picture.

[larrycavan]

Dom,

Ok..what I was after with that test was to see if disk position was having an affect beyond orifice selection alone. In other words, is there something we can't see related to the disk that is affecting your readings when you select any orifice except the 2" one.

So what did we learn?

You positioned the disk in a position that up till now yielded very low measurable flow. With the disk in that position but with the size of the hole reduced, measurable flow increased.

Ok..then it should be safe to establish that you had no leakage past the flowdisk from anywhere inside the top plenum.

You have enough power to pull enough pressure drop to max out the inclined scale with the orifice size temporarily reduced.

Next logical progression would be to incrementally increase the size of the orifice and continue testing....see how far you can increase it before you run into low readings...

Looking at the photos.....it looks like there is a fairly large gap between the sealing ring and the flowdisk. It's less of a problem on intake testing but exhaust tests my reveal a problem. The finger setup helps to overcome the problem but looks like it introduces another potential problem in itself.

The shape of the fingers are probably having a big effect on flow through the selected orifice. They look like they are going to have progressively more influence as the range is changed to larger orifices because they get progressively closer to the edge of the orifice.

Can you temporarily remove them or possibly cut them back away from the orifices?

Larry C

[Mousehouse1]

Dom I will do a few more tests in the next couple of days and see what all 10 motors will do. I am waiting on my checker springs to come back from a friend. I knew I should have bought 2 sets of those.

I believe I used 3 motors the last time I did a leakage test. I turned on 4 and the bench went over 32". My plexi-glass front panel didn't like that to much.

[Thomas Vaught]

Agree with what Larry posted.

I helped a guy in Nebraska build a orifice plate bench (stoppers) using 6 of the surplus motors.
He can pull well over 350 cfm at 28" with his deal.

160 cfm out of 4 motors seems very low when 6 will give over 350 on another bench. JMO

Tom V.

[Dom G]

Larry

Over the next few days I'll remove the fingers and run some additional tests then report my findings.

Thanks.

Dom

[larrycavan]

Dom,

Here's a pic of a setup that I think would work much better than the finger setup. It's far less intrusive to the air stream.

It would probably have some influence on the flow but ultimately your calibration will compensate for that.

[larrycavan]

Another view

[Dom G]

Larry

Originally I didn't think I would get a chance to do some more testing with the pressure fingers removed, but was able to con my 16 year old daughter into holding the head of the bolts that held the fingers in place while I loosened the nuts from under the bench.

In any event, I removed the fingers totally, recaulked a few spots and sealed off the holes where the fingers were.

Here are the results using the calibration plate and 2.531" orifice:

Test 1- Ran with orifice half covered again

Turned on 4 motors, got to 21" pressure when
inclined went to 100% - I was surprised it
performed worse w/o the fingers

Test 2 - Ran with orifice about 70% uncovered

Turned on 5 motors, got to 28" pressure and
inclined read an actual of 49%

Test 3 - Ran with orifice about 80% uncovered

Turned on 5 motors, got to 28" pressure and
inclined read an actual 25%

Test 4 - Ran with orifice fully open

Turned on 5 motors, got to 28" pressure and
inclined read an actual 12.25%


I expected more encouraging results than what I got. I think I need to regroup and decide how I'm going to proceed at this point. If I need to do major re-engineering to this bench to straighten it out; at this point, I am inclined to scrap it and build a pitot style bench.

Let me know what you think of the test results and if there's anything conclusive in them.

Thanks.

Dom

[bruce]

[larrycavan]

[Dom G]

Larry

That's the hole in the bench top where the head adapter mounts. I offset it because of all the comments made in the archives about avoiding a direct line to the orifice.

Dom

[larrycavan]

I see said the blind man....

Larry C

[Nick]

Let's see a picture of your incline scale. When you say 12%, what is the vertical rise of the water?


Nick

[Dom G]

To Larry .....and everyone whose attention I have captured with this thread, I found the problem!

The reason the numbers and test results did not make sense is because I'm an idiot.

Some of you know I'm using a 1 meter scale for my incline manometer. One of the things I've not done yet is create a chart converting the number from the manometer scale to a percentage.

In the meantime, I've been doing it manually and instead of calculating the percentage by determining the square root of the reading on the inclined, I've been squaring the reading. Obviously, it generates a dramatically different result.

I hopefully would have found the error in time, but really need to credit Nick for his last post asking me for a picture of the incline scale and the vertical rise level. Not wanting to publish something that was incorrect, it provoked me to re-examine my notes and recalculate a few of my last tests....then it hit me what I had done.

Now I need to rerun my tests to see where I'm really at.

Thanks for your support and indulgence.

Dom

[larrycavan]

Dom,

You're not an idiot....you're human!

I'm going to pour myself three fingers of JB....sit back and feel pretty good about you're discovery and GLOAT in the delight of an orifice bench that was saved from the scrap heap [Yo Bruce...that's a dig there buddy ]

One For All and All for One....'er somethin like that...

Larry C