calibrated orifice plate ?? - orifice plate

[larrycavan]

Here's that bench's pickup location

[ThomasVaught]

Curtis,

There are actually three probes used in most flow benches:

A Test pressure probe that is in a "quiet" area of the bench (allows you to set test pressures at 10", 25" 28", etc).

The Delta P Probes that are used to measure the Delta P across the flow orifice. On the Blue bench the upper and lower probes are about 1/4" off the surface and about 1/2" from the edge of the wooden opening on the bench. These probes seem to be in a general central area of the bench.

The probe you are referring to I thought was the test pressure probe and not the delta P probes that people have supplied pics of. Which one do you need help with? I am confused.

Tom V.

[cboggs]

Larry,

Your brake line idea is cool, .. I'll try it later when I have some time.

I can't even see the pick ups for the orifice disc , .. so I have
no idea where they are and can't tell if they will be influenced
by velocity.

I think your assessment of the pressure pick ups and velocity
is proving to be accurate. I have already proven that the test
pressure pick up below the test opening is being influenced
by the velocity. Now I'd like to look at the pick ups for
the orifice disc too, .. but I can't get to them without
tearing a new flow bench apart, .. and I'm not doing that.

I tried a few shielding ideas learned from my last go at this, .
foam, shielding etc, .. nothing had an effect other then
moving the pick up point.

About the bench not being right after I spent good money to
avoid this, .. yes I'm not happy. I'm a very busy shop and
bought one to save the time of building one, .. now I've got
to re-engineer the #### thing.
It is what it is, .. I have to move on and get over that as it
won't solve anything. The good side is I / we can help these
people build a better product.
I don't want to publicly "hang" anyone, .. myself, .. and we as a
group have influence on other people, .. they listen
to us, .. with that comes responsibility to avoid hurting those
who don't deserve it.

What I think is more important is what it will contribute to the industry.
I have a BIG issue with all the shops who lie about flow numbers
to make sales, .. put stupid flow numbers in magazine ads etc.
It REALLY gets under my skin, . so the last thing I want is
a commercial flow bench builder making benches that
boost numbers by 30 cfm !!!

If it was 2-3 cfm I could easily live with that, .. not 30 !

If you don't know it yet, .. the little pass around plate deal
proved several things, .. the primary one is how well
you can calibrate with a sharp edged orifice plate, ..
and how close several different benches can be.

On another note, .. my CnC machine, . I bought the first machine
the company made, .. and spent the year working out all the
bugs and passing that info back. They aren't going to tell the
world I helped re-engineer their machine, .. but they have
more then made up for it, I've been very well taken care of.

So, .. back to the task at hand, . . . this bench design is almost the same
as a Big Blue bench of 600 fame, . . so, .. can it be as simple as moving
the pressure pick ups to a location in the back corner where velocity
and any air movement will not influence them ???

here's a photo of the top 1/2, . ..


Thanks gang, .. really, .. thank you.

Curtis

[cboggs]

[ThomasVaught]

Curtis,

If you are trying to compare to someone else's bench at 28" of water and your probe is actually giving you an error in the checking point then I can easily see the shift in the evaluated parts flow numbers between the two benches.

Show of hands of how many have actually checked the test pressure manometer reading for accuracy:

Tom V.

[gofaster]

On my Baby Blue Bench (110), testing at 10", the Perf Trends sampling tends to settle after about 1 or 2 seconds, then I hit record, and it averages 10 samples. My test pressure manometer usually rads a little bit over the 10" mark. PT says it's 9.98" to 9.99".



Edited By gofaster on 1186177034

[larrycavan]