Cubic Feet of Argon required to fill a tank under vacuum

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Discussion Overview

The discussion revolves around calculating the volume of Argon gas required to fill a 250 cubic foot tank that is under vacuum (1x10-5 Torr) to atmospheric pressure (14.7 psia) at an ambient temperature of 90 degrees Fahrenheit. Participants explore various aspects of gas behavior under different conditions, including the Ideal Gas Law and the implications of initial pressure conditions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant questions the simplicity of calculating the volume of Argon needed from a vacuum state.
  • Another participant suggests that the required volume of Argon would be approximately 224 cubic feet, factoring in temperature adjustments from standard conditions.
  • A different viewpoint emphasizes that the initial pressure of the Argon gas is crucial for determining the volume needed, indicating that without this information, the question cannot be fully answered.
  • One participant mentions the use of the Ideal Gas Law for volume calculations and references the van der Waals equation for non-ideal gas behavior.
  • A participant humorously requests more information about the tank size to provide an answer regarding the volume of Argon corresponding to a specific weight.

Areas of Agreement / Disagreement

Participants express differing views on the calculations and assumptions involved in determining the volume of Argon needed. There is no consensus on the exact volume required, as factors such as initial pressure and temperature adjustments are debated.

Contextual Notes

Participants highlight the importance of knowing the initial pressure of the Argon gas and the implications of temperature on gas volume, indicating that assumptions about standard conditions may not apply directly to this scenario.

Who May Find This Useful

Individuals interested in gas laws, thermodynamics, or practical applications of gas behavior in engineering contexts may find this discussion relevant.

Nathan Smith
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I have a tank that is 250 Cubic Feet.
The tank is under vacuum (1x10-5 Torr).. which is actually 1.93368e-7 psia.
How much Argon, in cubic feet, does it take to back-fill to atmosphere or 14.7 psia?
Ambient temperature in tank is 90 degrees.
 
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Nathan Smith said:
I have a tank that is 250 Cubic Feet.
The tank is under vacuum (1x10-5 Torr).. which is actually 1.93368e-7 psia.
How much Argon, in cubic feet, does it take to back-fill to atmosphere or 14.7 psia?
Ambient temperature in tank is 90 degrees.
Hello Nathan, :welcome:

I don't suppose you mean 250 cubic feet ? But then: what do you mean ?
 
Is it that simple from a vacuum?
 
Nathan Smith said:
I have a tank that is 250 Cubic Feet.
The tank is under vacuum (1x10-5 Torr).. which is actually 1.93368e-7 psia.
How much Argon, in cubic feet, does it take to back-fill to atmosphere or 14.7 psia?
Ambient temperature in tank is 90 degrees.

Well, it will take about 250 cubic feet. Gas volumes are normally quoted at STP (standard temperature and pressure, which is 0 degrees C and 1 atm). You want 1 atm of pressure and 90 degrees. I'm going to assume, since your other measurements are in English units, that you mean 90 degrees F, which is 305 degrees K. So the volume of the gas will increase by 305/273, so you will need somewhat less than 250 cu ft of gas. You will need 250*273/305 = 224 cu ft of Ar to fill your tank. So one large gas cylinder will do it.
 
Pretend that the initial vacuum was perfect. Then your question is how much argon does it take to occupy 250 cubic feet at 90 degrees F?

The answer can not be given in cubit feet, because we don't know the pressure of the argon before it was put into this tank. You may be getting the argon from another tank at 1000 psi.

Wolfram alpha is a good source for such questions.
slask.png


Now your next question is how many cubic feet is 25 pounds of argon? You have to tell me the pressure to answer that.
 

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The source 130 PSI supply pressure from a 16 pack of Argon cylinders with 5721 cubic feet of gas storage.
 
It's been too long since I did this stuff but the Ideal Gas Law is used to determine how much volume an IDEAL gas occupies at different temperatures and pressures
https://www.engineeringtoolbox.com/ideal-gas-law-d_157.html

and the van der Waals equation is used to adjust for the fact that different gases behave differently and thus DEVIATE from the IDEAL equation's results. The following link explains it and has data for 200 or so different gases, including Argon.

https://www.engineeringtoolbox.com/...-Waals-equation-constants-gas-law-d_1969.html

Hope this helps. I'm not a physicist, just remember some of this from my brief stint in engineering school roughly 1000 years ago.
 
anorlunda said:
how many cubic feet is 25 pounds of argon?

Tell me how big your piece of string tank is and I will tell you how big the argon becomes. At least for reasonable sized tanks.

BoB
 

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