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

• avishay
In summary, the conversation is discussing the calculation of pressure needed for a certain flow rate of Argon gas. The setup includes a tank of Argon gas with a line pressure range of 0 to 5 bar, and a pipe with an internal radius of 2.3mm. The conversation also mentions the need to consider pressure drop, which is a function of length and can be calculated using various variables. The methodology for solving this type of problem is presented in a book called Transport Phenomena, and it is important to take into account the compressibility of the gas.
avishay
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 :)

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 ?

russ_watters
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).

## 1. How do I convert pressure from Bar to flow rate in L/min?

To convert pressure from Bar to flow rate in L/min, you will need to use the Bernoulli's equation, which states that the pressure and flow rate are inversely proportional to each other. This means that as pressure increases, flow rate decreases and vice versa. You will also need to know the specific density of the fluid in question and the diameter of the pipe or channel through which the fluid is flowing.

## 2. What is the formula for converting pressure from Bar to flow rate in L/min?

The formula for converting pressure from Bar to flow rate in L/min is: Flow rate (L/min) = (Pressure (Bar) x Area (cm²) x 60) / (Specific density (g/cm³) x 1000). This formula takes into account the Bernoulli's equation and the units of measurement for pressure, area, and specific density.

## 3. Can I use the same formula for all types of fluids?

No, the formula for converting pressure from Bar to flow rate in L/min may vary depending on the type of fluid being used. Different fluids have different specific densities, which will affect the conversion. Additionally, the viscosity of the fluid can also impact the flow rate and may require a different formula to accurately convert from pressure to flow rate.

## 4. Is there a simpler way to convert pressure from Bar to flow rate in L/min?

Yes, there are online conversion calculators and software programs that can quickly and accurately convert pressure from Bar to flow rate in L/min. These tools take into account all the necessary variables and provide a simple and convenient way to convert the units of measurement.

## 5. What are some common mistakes to avoid when converting pressure to flow rate?

One common mistake to avoid when converting pressure to flow rate is not using the correct units of measurement. For example, using cm³ instead of cm² for area or using g instead of g/cm³ for specific density can result in an incorrect conversion. It is also important to ensure that all the variables used in the formula are for the same point in the system, such as the inlet or outlet of the pipe or channel.

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