Correction (temp/humi/baro) and pitot tubes in a orifice FB

Discussion on general flowbench design
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paulo_aa
Posts: 60
Joined: Thu Feb 21, 2019 1:14 pm
Location: Brazil

Correction (temp/humi/baro) and pitot tubes in a orifice FB

Post by paulo_aa »

Hello guys.

I have searched and read a lot in the forum about corrections. Learned the basics:

- Orifice flow benches like PTS design don't need corrections due to its orifice ratiometric working principles, once the air that passes and is measured through both the orifices is the same.
- Pitot tube flow benches need corrections to get the math calculations in order to result in a CFM number.

In my flow bench I installed an air temperature and humidity sensor inside the upper chamber and a display in the panel.

Having that in mind I would ask you:
- When using velocity probes (pitot tubes), I have to apply corrections in the Flow Soft Configuration Screen, in order to have correct measurings? Which corrections are needed?


And, risking to be that kind of person whom don't do a good search in the forum and asks something that was already answered:

- My question is: Why there are fields in the Flow Soft Configuration Screen related to air characteristics, fi this type of FB don't consider them?

- Here in Brazil's Northeast, the air temperature is high. In intake mode, I am getting 30 Celsius grades (86F), way different of the 70.05F that is standard in the Flow Soft.
I should put these value in the Flow Soft Configuration Screen?
When testing in exhaust mode, I am getting more than 53 Celsius Grades (127,4F).

- I tried to change the Air Temperature in the Flow Soft, and looked for changes in the Air Density value in the same screen.
But id didn't changed. Air density is based in on its temperature, so this value should be changed automatically when I change air temperature value? Or not?


Sorry if it is some are more of the same questions aready existing in other threads...
Brucepts
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Re: Correction (temp/humi/baro) and pitot tubes in a orifice

Post by Brucepts »

Pitot tubes use temp/baro correction factors.

Changing the temp/baro will have such a small change on your FPS it will hardly be noticeable due to the fact you can not get the probe in the same location on every test you run. Unless you have a wide swing of conditions in your shop just leave at the default would be my opinion.

We included the option to make the changes in the software for those who would like to have that option to make changes.
Bruce

Who . . . me? I stayed at a Holiday in Express . . .
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