PTS DIY flow sensor

[cre]

My DM I just arrived this morning, very good news

[MrHijet]

[bruce]

For everyone who has been following this project;

I know when we started this thread the PTS Digital Manometer project was going to be a DIY'er project, as we progressed into the design it was felt that it reached beyond the DIY stage with the time and skills involved with the assembly, calibration and final assembly.

I'd like to show just one part of what's inside the "box" so you all get a better idea of what we have accomplished in our quest. I showed the prototype PCB early-on in the design but here it is in it's final stage.

[msj442]

you are right on the slow numbers with large plate bruce. i have a 750mhz laptop and it does the same thing. the smaller plate does not notice this as much as they respond right away.

jmo, max

dm is awesome guys!!!! it is worth the wait. remember bruce hand builds and tests every one.

[49-1183904562]

[color=#000000]C'mon Max you mean he does not have one of those fancy robotic machines that bends all the component leads and solders it al together for him?

I've seen Bruce

[msj442]

lol. just thought i would see if i could lift the heat a little on bruce. :laugh:

max

[MMack]

Just got mine half way hooked up, loving the velocity measurements! The PTS stuff has worked great! The POS laptop I am using, not so much! The power cord is iffy, the mouse is touchy, and I found that it did not have a winzip program to open the software.

But now it works, and all is well in the world!!

Mike

[MrHijet]

I received my PTS DM yesterday. I had to drive to the customs office in the neighbor town and had some discussions what this electronic device is made for
(I remember similar discussions when I received the orifice disks from Bruce at the customs office ...)

The digital manometer looks great. As the temperatures are rising, I really have to complete my flow bench now.

Thanks for the quick shipping!

Daniel

[RVG440]

I am new to the forum and am building my own simplistic bench design. I have not yet had a chance to read all 15 pages so these questions may have been answered already so dont shoot the messenger.
I have 2 questions. i am eager to buy the digital manometer.

1. does the box read in reverse flow for the exhaust?

2. does the unit automatically calibrate itself incase my motors are only pulling say 8 inches or less and convert it to 28 inches on the display screen?

thanks for your help.

[bruce]

1. You need to swap the connections for reverse flow. This can be done using a Clippard MTV-5 valve, info on this can be found here on the forum.

2. There is a pop-up window (user selectable) that shows flow converted to any pressure you want.

The PTS DM is setup to work with a 16" Dp across the orifice plate installed in your flowbench, keep this in mind. The PTS DM was designed to compliment my PTS Flowbench plans.

We are looking at a smaller Dp sensor but at this time do not have a working prototype. I have the sensors but haven't had time to work on it yet. This will allow us to support smaller bench builds. There is a trade off in accuracy as you come down in Dp though as orifice plate holes need to be larger. We are hoping that using a smaller Dp sensor will overcome this problem. Most of the other DM's on the market are using a 40" Dp sensor so if you are reading 8" of Dp you are only using 20% of the sensor's range which puts you in the lower part of the sensor's scale.

[RVG440]

Bruce,
how much for the clippard MTV-5 valve and do you have them?

regarding the Dp. i am not to familuar with the pressure termonlogy so bear with me :p

from what you are saying i would still be better of with your unit reading 16 " than the competitor units at 40 ".
am i reading this correctly.

Thanks for your time as i am very new to this.
Regards Simon

[bruce]

I do not have any Clippard valves for resale.

What I am saying is this; we use a 16" Dp sensor and use a 16" Dp orifice plate or 100% of the sensor's range. If someone uses a 40" sensor and only uses 6,8,10, 16 Dp etc they are only using a percent of the possible range.

A sensor has a working range much like an inclined manometer does and you should try and stay in that range. The sensor's are way more sensitive than a water gauge though so they tend to work in the lower part of the scale. We see this with the 16" sensor when using a large plate internally ie 400cfm and trying to measure down to ~25cfm. Depending on your averaging and computer speed your numbers might be slow to change on screen.

We are using the full range of the sensor, imagine if you were only working in a percent of the total range of the sensor? In order to take full effect of a 40" sensor you would need a 40" Dp for the full range.

Currently, with the PTS DM you need to use a 16" Dp across the plate. The math within Flowsoft only works in this range, this was done for the best possible linearity across the working range. This means you need to have 16" more vacuum below your plate than above the plate for 100% across the plate.

It really can be confusing . . . and we are still learning what we can do with this DM.

PS: I'm also looking at 100" sensors for static pressure for those who want to test above 38". My PTS Bench design does not allow for testing above 38" due to it's basic simplistic design in construction.

[RVG440]

Bruce,
thanks for your time. I just placed an order for the digital manometer via pay pal and am looking forward to recieving it.
I hope you have them in stock as i am like a kid in a candy shop right now.
regards Simon

[charlieb]

Bruce,

Does you DM have a wide enough range that a single orifice bench is practical? This is assuming that the orifice would be sized so a full 16" differential would be seen at or just above the maximum port airflow.

Charlie

[bruce]

I would say from my testing that a range of 350-400cfm is a good working range. One thing you will notice is on the lower end of the range ie below 25cfm, depending on how you have the averaging set the readings will be slow to change on the screen. If you plan on testing lower cfm ranges I recommend changing to a smaller plate.

I am using a 400cfm range plate on my personal bench and the parts I test for myself are less than 125cfm.

Bruce