Not the Mercdog again

[1960FL]

When in sharp focus, its amazing what you can see if the image is made big enough.

then you hook up a digital oscilloscope to the mains fine tune the axis adjustments and WOW you see voltages all over the place some as high as thousands of volts! Noise, leakage, EMF etc.

Grey I think rather than chase the tail, maybe if you let us know what even if possible it is that you are expecting from any of these DM's, PTS, FP1, C&D? 3 CFM at 100 is way within reason! just not sure where you are going with all this.'

Rick

[Old Grey]

Grey I think rather than chase the tail, maybe if you let us know what even if possible it is that you are expecting from any of these DM's, PTS, FP1, C&D? 3 CFM at 100 is way within reason! just not sure where you are going with all this.'

Rick

Nothing really, just curious.

The owner of the Mercdog has lost interest somewhat so I have this bench lying around while he's making the fluid manometer, and because I see it everyday I keep thinking about stuff.

I'm not really worried about about ultimate accuracy but more repeatability, because if it's repeatable it can be made accurate with compensation factors in software - if the 100cfm is always going to read 107 cfm, why not just subtract it -.

How about fitting a manometer tube beside a transparent plastic school ruler into the focal plane an old 35mm slide projector laying on its side, and project the image of both side by side onto a wall.
It will look absolutely huge next to the ruler scale, which might have sixteenths of an inch or millimeter graduations.
When in sharp focus, its amazing what you can see if the image is made big enough.

Optical amplification, and I though I had some ideas.

I was thinking about a Lazar distance measuring device reflecting off the fluid level of a fluid amnometer , and then I started thinking about mass of the fluid and it's inertia damping it's movement - I think too much -

[Tony]

Optical amplification, and I though I had some ideas.

I was thinking about a Lazar distance measuring device reflecting off the fluid level of a fluid amnometer , and then I started thinking about mass of the fluid and it's inertia damping it's movement - I think too much -

One day they will invent a medical cure for people like us LOL !!!

[Old Grey]

I reckon if you put a 40" sensor in the PTS DM it's robust averaging will make the difference nearly neglectable, or at least very small.

It was, the first test version of the board had 3 40" sensors and the only reason we went to 16 was that it showed better linearity across a range on an orifice as we has no intention of a 40" Delta P.

Rick

When you used the 40" did you use the whole 40", or just the first 16"?

One day they will invent a medical cure for people like us LOL !!!

I LOL your LOL

[Old Grey]

I thought I would move the averaging tube away from the wall - it's hard to tell what air is doing in this weird shaped chamber but the POS FB showed that air smashes against walls while it looses energy -, so I looped the AT in a 12" circle on the board around the orifice.

40" dep, reading 28" converted, sample rate low at #3
40.0 301.7 300.2
40.1 300.3 298.8
40.0 302.2 300.7
40.0 300.2 298.7
40.1 301.7 300.2
40.1 301.6 300.1
40.1 301.0 299.5
40.2 300.0 298.5
40.1 301.9 300.4
40.0 301.4 299.9
40.0 304.2 302.7
40.1 299.3 297.8
40.0 303.8 302.3
40.0 302.0 300.5
40.0 302.0 300.5
40.0 301.4 299.9
40.0 301.1 299.6
40.0 303.0 301.4
39.9 303.9 302.4
40.0 301.0 299.5
40.0 300.4 298.9
40.0 300.9 299.4
40.0 301.2 299.7
40.0 301.2 299.7
40.1 298.7 297.2
40.1 299.7 298.2
40.0 301.1 299.6
40.0 302.4 300.9
40.0 300.6 299.1
40.1 300.8 299.3
40.1 298.8 297.3
40.1 302.3 300.7
40.1 298.5 297.0
40.2 301.4 299.8
40.1 300.0 298.5
40.1 299.3 297.8
40.1 302.4 300.9
40.1 303.4 301.9
40.1 301.0 299.5
40.1 303.2 301.7
40.1 302.2 300.7
40.1 301.5 299.9
40.1 300.8 299.3
40.1 301.5 300.0
40.1 303.8 302.2
40.1 302.6 301.1
Difference of 5.5, and 5.0 max and min subtracted
The stability of the AT seams to be a touch more steady

0.040" restrictor on end of tube encased in a housing at 28" max to min = 8.5cfm
Averaging tube at 28" max to min = 11.2cfm
Each set of readings had erroneous blips that that accentuated the difference between max and min, so if the highest and lowest was removed it would be 5.9cfm and 5.5cfm.

40" dep, reading 28" converted, sample rate max at #20
40.1 301.5 300.0
40.3 301.6 300.0
40.2 299.5 298.0
40.1 302.0 300.5
40.1 301.7 300.2
40.1 301.0 299.5
40.2 302.1 300.6
40.1 302.0 300.5
40.1 301.4 299.9
40.1 299.8 298.3
40.2 301.8 300.3
40.3 301.7 300.2
40.3 300.5 299.0
40.3 300.4 298.9
40.2 301.3 299.8
40.3 301.2 299.7
40.3 300.5 299.0
40.3 301.2 299.6
40.3 302.3 300.8
40.3 302.0 300.5
40.3 302.0 300.5
40.3 300.6 299.1
40.3 300.9 299.4
40.3 302.0 300.4
40.3 301.6 300.1
40.3 302.0 300.5
40.3 302.5 301.0
40.3 302.3 300.8
40.3 300.7 299.2
40.3 301.8 300.3
40.3 301.9 300.4
40.3 300.8 299.3
40.3 302.8 301.3
40.3 301.6 300.1
40.3 302.8 301.3
Difference of 2.8, and 2.3 max and min subtracted

Then I did this weird thing and tested it at 28"
28" dep, reading 28" converted, sample rate max at #20
28.0 301.2 299.7
28.0 300.0 298.5
28.0 299.2 297.7
28.0 299.7 298.2
28.0 299.1 297.6
28.0 298.8 297.3
28.0 299.2 297.7
28.0 298.0 296.5
28.0 300.4 298.9
28.0 298.9 297.4
28.0 299.4 297.9
27.9 299.2 297.7
27.9 299.3 297.8
27.9 298.7 297.2
27.9 299.7 298.2
27.9 299.7 298.2
27.9 298.9 297.4
27.9 299.8 298.3
28.0 298.7 297.2
28.0 298.7 297.2
27.9 299.0 297.5
27.9 298.8 297.3
28.0 300.4 298.9
27.9 298.6 297.1
27.9 299.6 298.1
27.9 298.7 297.2
27.9 299.5 298.0
27.8 298.9 297.4
27.8 299.4 297.9
27.8 299.6 298.1
27.8 299.8 298.3

Even though I didn't change the cd, the cd seams to have to be different for different deps. Weird

So I went back to my 3.33" 3mm square edge internal orifice and cal-ed the top 300 PAP plate at 28" with 0.578.
I then tested it at 28", and max of 6 motors 40", and this is what I saw.
27.8 301.7 300.1
27.9 300.9 299.4
27.9 302.1 300.6
27.9 302.2 300.7
27.9 302.1 300.6
27.9 301.8 300.2
27.8 302.0 300.5
27.8 302.8 301.2
27.8 302.2 300.7
27.8 301.4 299.9
27.9 301.1 299.6
27.8 301.5 300.0
27.9 302.4 300.9
27.9 301.4 299.9
27.9 302.4 300.8
27.8 302.5 301.0
27.9 302.2 300.6
27.9 301.8 300.2
27.9 301.1 299.6
28.8 303.3 301.8
32.0 304.1 302.6
33.6 303.8 302.2
34.4 304.0 302.5
35.8 306.5 305.0
37.8 305.7 304.2
38.8 305.5 304.0
39.3 305.7 304.2
39.6 305.1 303.6
39.9 305.9 304.3
40.2 304.8 303.3
40.4 305.0 303.5
40.5 305.1 303.5
40.5 305.6 304.0
40.5 304.9 303.4
40.4 305.5 304.0
40.5 305.0 303.5
40.5 305.7 304.1
40.5 305.3 303.7
40.4 305.8 304.3
40.4 304.7 303.2
40.4 305.9 304.4
40.4 305.7 304.2

[jfholm]

This is exactly one of the things I wanted to see with my smoke testing of an orifice. I really feel that the cd of an orifice gets larger when you apply more pressure. It is just for curiosity sake though.

But we need to remember that if we do our flows the same way every time then we will have our repeatability and will be able to tell if we are making improvements. I think it is more important that we compare against ourself and not try to match somebody else's readings. I have a friend with a Super Flow bench that he knows reads low compared to others, but he still makes winning heads because he just compares to his own work. He makes some very good heads and that is what is important. IMO

John

[Old Grey]

This is exactly one of the things I wanted to see with my smoke testing of an orifice. I really feel that the cd of an orifice gets larger when you apply more pressure. It is just for curiosity sake though.

But we need to remember that if we do our flows the same way every time then we will have our repeatability and will be able to tell if we are making improvements. I think it is more important that we compare against ourself and not try to match somebody else's readings. I have a friend with a Super Flow bench that he knows reads low compared to others, but he still makes winning heads because he just compares to his own work. He makes some very good heads and that is what is important. IMO

John

That's what I was also thinking about when large orifices are used to measure low flows. If the DM is always reading 107 with a 100 orifice it can't really be the DM because it's repeating the same error each time, and that makes me ask if it's the mechanics of the orifice discharge. It's got to the stage that to get accuracy you need a 3D cd table like an EFI table, which is weird because with DM you can do it in software.

I'm not that fussed with accuracy but I want a stable figure that repeats, and that's what I'm testing, it's just that I stumbled upon this interesting phenomena.

Now it's got we thinking if Bruce's sharp edge orifice does that same thing, so I might crack out the bench again just to see if sharp edge is more stable than 3mm square edge.

[Brucepts]

That's what I was also thinking about when large orifices are used to measure low flows. If the DM is always reading 107 with a 100 orifice it can't really be the DM because it's repeating the same error each time, and that makes me ask if it's the mechanics of the orifice discharge. It's got to the stage that to get accuracy you need a 3D cd table like an EFI table, which is weird because with DM you can do it in software.

I'm not that fussed with accuracy but I want a stable figure that repeats, and that's what I'm testing, it's just that I stumbled upon this interesting phenomena.

Now it's got we thinking if Bruce's sharp edge orifice does that same thing, so I might crack out the bench again just to see if sharp edge is more stable than 3mm square edge.

When we decided to design and build the PTS DM my thought was to keep it as simple as possible for the average user to use, we accomplished that goal by keeping the calibration and software package as simplistic as we could by using just the Cd to "calibrate" the DM. We know from testing that we can do other things with it to improve the software such as lookup tables and a calibration factor. My idea was to keep the DM reading on a water column scale and not stray away from that which keeps it pretty simple to get a repeatable numbers product that reads the same for anyone who has one on a flowbench. This will be 98% of the users, some of which have little to no detailed computer knowledge and just want something that gives repeatable accurate numbers.

Then you have the 2% that want to tweak the accuracy as much as they can and we get that. We have to keep in mind those 98% users and not make this DM so complicated that it drops them out of the market on a simple to use product, so we end up with a balancing act. Rick and I discuss this pretty much a few times a week in our phone conversations on how we can improve the product and suit everyone who wants to use it (he likes .00000000 and I am happy with .000 of accuracy so we don't always agree ). Personally, I think we have only scratched the surface on what we can do with the PTS DM but it is a balancing act of the 98/2% of keeping it simple to setup and operate for which I will side with the 98% crowd. I am the one who interacts daily with the end-user and have a pretty good understanding of what they are looking for. Having built and shipped over 300 DM's now I think the market understands what they are getting from PTS and are quite happy with it

We have shared way more of the design and software than any other manufacture of a product would be willing to on an open forum and behind the scenes! Looking back now we would probably do things a little different with some of the sharing part of the inner working of the DM and software. But, it is what it is and we will are moving on . . .

[Old Grey]

By all means keep your intellectual property, it's just that in this App world peoples coding is only limited by imagination.

I suppose people only use 1 test dep, so it's over kill, but you could have 4 calibration plates and flow them at different deps so that the points could be made into a self assembling table by code.

My friend used to code on one of the first electronic g/box in 1980, and he said to Ford that for the price of a switch they could shift gears electronically. They declined because they didn't think ahead, and now you see paddle shifters everywhere.

I still think a complete SF retro fit kit with multiple orifice facility would sell mainly because the others are so expensive - Performance Trends is min $800 hardware + software -.

[Old Grey]

Well I made a very rough sharp edge orifice - 3.33" 0.572 cd - and it's pretty much the same.

28.0 301.7 300.2
28.0 300.7 299.2
28.0 300.7 299.2
28.0 301.2 299.7
28.0 301.2 299.7
28.0 300.7 299.2
28.0 300.3 298.8
28.0 301.4 299.9
28.0 301.6 300.1
28.0 301.6 300.1
28.0 301.7 300.2
28.0 301.0 299.4
28.0 301.5 300.0
28.0 302.0 300.5
28.0 301.2 299.7
28.1 301.9 300.4
31.5 304.4 302.9
33.4 303.8 302.3
34.5 304.2 302.7
35.2 303.8 302.3
35.7 304.4 302.8
36.0 303.7 302.2
36.3 304.4 302.9
36.5 304.2 302.7
36.7 303.9 302.4
36.9 303.1 301.5
36.9 303.1 301.6
37.0 303.8 302.2
37.0 303.3 301.8
37.0 303.6 302.1
37.0 303.2 301.7
37.0 304.1 302.5
37.0 304.0 302.5
37.0 304.5 303.0
37.0 303.1 301.6
36.9 304.6 303.1
36.9 304.6 303.0
37.0 304.1 302.6
37.0 303.4 301.9
37.0 303.6 302.1
37.0 303.8 302.3

I think someone else with a different DM has to try this because I'm not really confident that this old FP1 is that great, and at least we will know if it's an actual orifice behaviour.