How to convert pressure (Bar) to flow rate (L/min)?

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Discussion Overview

The discussion revolves around calculating the pressure in bar required to achieve a specific flow rate of 3 L/min for Argon gas, considering factors such as pipe length and internal radius. Participants seek to understand the relationship between pressure and flow rate in a gas system, with a focus on the necessary calculations and underlying principles.

Discussion Character

  • Exploratory
  • Technical explanation
  • Homework-related

Main Points Raised

  • One participant outlines the need to calculate the pressure drop, noting that it varies with pipe length.
  • Another participant expresses confusion about the calculation process and the relevance of the pressure drop.
  • A different participant clarifies that pressure drop is not a standalone parameter but a result influenced by multiple variables.
  • Reference is made to a methodology in a textbook that emphasizes the importance of considering gas compressibility when dealing with significant pressure changes.

Areas of Agreement / Disagreement

Participants exhibit uncertainty regarding the calculation process and the significance of pressure drop, indicating a lack of consensus on how to approach the problem.

Contextual Notes

Participants mention the need for additional information, such as pipe length, which is not provided. There is also an indication that the compressibility of the gas must be considered due to the large pressure change.

avishay
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hii,

I'm try to calculate the pressure (in bar) needed for a certain flow rate 3 L/min of Argon gas given the following setup:
- I have a tank of Argon gas and the line pressure can be between 0 bar to 5 bar.
- The gas will flow out to the open air in the end.
- My pipe has an internal radius of 2.3mm.

I will be very happy if someone can also explain to me the process of getting to the answer...

Thanks for the help :)
 
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Hello avishay, ##\qquad## :welcome: ##\qquad## !

Your problem statement isn't complete: for a short pipe the pressure drop is less than for a long pipe.

With the expressions in the link you can calculate ##\Delta p## for your pipe length.
 
I didnt really understod how to calculate this prameter, I'm not really sure why i need this...
any help?
:)
 
avishay said:
I didnt really understod how to calculate this prameter, I'm not really sure why i need this...
Pressure drop is a function of length or rather is given per unit length.
 
avishay said:
calculate this parameter
It's not really a parameter: according to the link it's a result of a bunch of variables.

What have you calculated yourself so far ?
 
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The methodology for solving a problem like this is presented in Chapter 7 of Transport Phenomena by Bird, Stewart, and Lightfoot. But, please note that, in a case like this where the gas pressure change can be as large as a factor of 6, you will need to take into account the compressibility of the gas, and, as such, will probably be working in terms of the square of the absolute pressure (rather than the absolute- or gauge pressure to the 1st power).
 

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