My name is Anthony and I just recently finished getting my PTS flowbench operational! Now I'm starting to dial in the computer program I'll be using. I'm currently using a Performance Trends DataMite Mini usb data logger and the current version of there Port Flow Analyzer program. But I'm have some incorrect readings when I flow my PTS orifice plates @ 28". My smallest orifice plate is calibrated at 100cfm @ 28 and the program is reading 2.8cfm @ 28" Do you see the problem here....
So my question is for anyone has a Performance Trends Port Analyzer. What are your calibrations settings for your PTS flowbench and where are you pressure pickup points? Unfortunately, I don't have any manometers hooked up to the bench to give me a manual reading because I was told I didn't need them because I went digital so I'll be ordering some ASAP.
First off welcome to the forum, second DO Not my manometers to debug your bench a yard stick and a coffee can of water will tell you if your close. ( if you understand the principles and math)
Post a picture of you software configuration screen and settings and i will try to point you in the right direction.
The PTS DM uses a 16" pressure sensor, I doubt that would be the range they are using, possibly they use a 40" sensor in which case all your ranges would be based on 40" not 16" so the calculations in the software would need to reflect the sensor that is used in that DM.
If you used 16" you would only be using 16" of the 40" sensor and you would need to "stretch out" your calibration so 100cfm = 100cfm. Doing this you loose sensor resolution
Just my observation . . .
Bruce
Who . . . me? I stayed at a Holiday in Express . . .
before we go any further just how is this unit connected to the flowbench to measure. 1. Static Pressure/Test Pressure and 2. The differential pressure across the internal orifice plate?
On the PT site i do not see where this device even measures pressure, or are you using their Blck Box?
Well, after being on the phone for a hour and having PT remote access the program to see what's going. They found that the Inclined Flow Manometer setting was reason for the incorrectly readings. They switched it from 100 to 19. Now when I flow the 1.180" orifice plate it repeats with 1-2 cfm(100cfm) now @ 28". Wish I knew how he figured it out, was interesting how they were checking around the program to figuring it out lol I'm very novice to understanding how calibration are figured out but when it comes to testing with the Port Flow Analyzer I'm very familiar it. Just glad is reading the cfm correctly.
I tested one more plate to seeing how it reads and it flowed 286 @ 28" and the calibration rating was for 300cfm. Still close in my books, I blame the humidity in the air since was pretty humid! Thank you all for your input!
Too answer your post, here is the layout for this data logger to have a better understanding of it. It's hooked up the same way according the air schematic from the PTS plans except the hoses are reversed for the Test pressure for it to read correctly.
1960FL wrote:
Performance Trends DataMite Mini usb data logger
before we go any further just how is this unit connected to the flowbench to measure. 1. Static Pressure/Test Pressure and 2. The differential pressure across the internal orifice plate?
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I think you are close, you need to find out why you are off 14/15 cfm at the 300 plate, I would change the incline number to say 20 and teat again see how much difference you get between 100 and 300 also where do you input the CD value for the plate and what value are you using?
Rick
PS the reason i asked about how you were get pressure is the PT site shows that the Mini does not have pressure taps ???
1960FL wrote:where do you input the CD value for the plate and what value are you using? how you were get pressure is the PT site shows that the Mini does not have pressure taps ???
Yea, I might play with that setting more since I have a master copy of it now. Stupid question, does humidity effect cfm readings at higher flow? It was really humid when I got that reading.
I enter the 16" value under the "flow ranges" section of the program since I have four PTS plates in my Flow Bench setting. So the 75/226/378/625cfm. When I flow test, I need to select the correct range or it throws off the reading.
If I'm understanding the last question, The datamite is getting the readings from the actually PTS pressure pickup points. If I built a "Performance Trends bench" their pickup points are incline with the airflow(flow is direction through PVC pipes) so the test pressure would be directly under the cylinder head and the flow pressure(cfm) would on either side of the orifice plate inline with it. Hope that answers your question! I believe they have the build plans for one of their benches on the PT site.
Ok so i will try to answer this but partially blind, the PTS bench is an orifice int a box design and thus makes it ratio-metric meaning the air on each side of the plate is basically the same air. I/E we are testing pressure on each side of the plate and it is not changed from one side to the other, in other words we are not adding moisture o temperature to it as it passes through the bench. The opposite of this might be and SF 110/120 where the test air passes through the motors and your orifice is split between atmosphere and the inside of the bench.
As for your condition i do not know if the box is taking into consideration/adjusting for the atmospheric conditions automatically.
Things to consider.
Bruce's plates are designed with a theoretic .62 CD and stand atmosphere at i think 70°F
Do to air flow in your bench (Potential turbulence) you bench may not calibrate to a .62CD
The flow through an orifice plate is not 100% linear this is why we try to calibrate 100% at 50% of the internal plate flow and try not to flow more than 90% when testing.
Last to better understand the math and effects of CD and Delta P i suggest you find Ed's flow calc spreadsheet on the forum and fool with different scenarios in calibration you may be able to set your max incline to 16" and a .62CD or maybe 17" and a .60CD to get the proper calibration.
My take is they have a 100" sensor in that box, hence the reason for 100, see my post about 16 to 40 above. By making your scale 19 now it calibrates the PT box to only use 19" of their sensor in the calculations. You now have limited yourself down to 19% of the sensor range. Your plate is now using 19% of a 100" sensor to read 100% of the plate range which is a serious loss of resolution depending on the bit count of the ADC that is being used.
Rick: Think the "calibration factor" shown in the pics is their name for Discharge Coefficient? Depending on what you have in that configuration block you would need to change your scale ie 19 instead of 16 that the plates are machined to.
Now that I have thoroughly confused you, I am not familiar with the PT product so as long as they got it working they should know . . .
Bruce
Who . . . me? I stayed at a Holiday in Express . . .
