Can a Subsea Lifting Bag With CO2 Rise to the Surface?

Click For Summary

Discussion Overview

The discussion revolves around the buoyancy of subsea lifting bags filled with different gases, specifically comparing CO2 and O2, and their ability to rise to the surface when submerged in water. Participants explore the implications of gas density and mass on lifting capacity, as well as the forces acting on the lifting bags.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether a subsea lifting bag filled with CO2 would rise to the surface similarly to one filled with O2, noting that CO2 is less dense than water.
  • Another participant challenges the initial assumption that 37% more CO2 would be needed to lift the same mass as O2, prompting a consideration of water density.
  • A reference is made to a similar discussion comparing the lifting power of Hydrogen and Helium in balloons, suggesting a broader context for the topic.
  • One participant emphasizes the importance of considering the mass of the gases in the lifting bag and suggests that the type of gas has a minimal effect on buoyancy when submerged.
  • A later reply acknowledges the need to account for forces such as F=ma and drag forces in the analysis.

Areas of Agreement / Disagreement

Participants express differing views on the lifting capacity of CO2 compared to O2, with no consensus reached on the correctness of the initial calculations or assumptions regarding gas density and buoyancy.

Contextual Notes

Limitations include the need for clarification on the density of water and its role in buoyancy calculations, as well as unresolved considerations regarding the effects of drag forces and the mass of the gases involved.

cps.13
Messages
40
Reaction score
1
This may sounds like a stupid question but...

If you were to use a subsea lifting bag filled with O2 it would rise to the surface.

Would the same happen with CO2? I assume the density of CO2 is different so the amount required would be more or less than O2, but it is still less dense than water so should rise?

Thanks

Edit:

After looking on google I can see that CO2 is 1.824 Kg/m3 whereas O2 is 1.331 Kg/m3. So you would therefore need 37% more CO2 to lift the same mass using O2.

Is that correct?

Thanks
 
  • Like
Likes   Reactions: Xilus
Physics news on Phys.org
cps.13 said:
After looking on google I can see that CO2 is 1.824 Kg/m3 whereas O2 is 1.331 Kg/m3. So you would therefore need 37% more CO2 to lift the same mass using O2.

Is that correct?
No, it is not correct.
What is the density of water and how does that figure in?
 
There is a similar question, comparing Hydrogen and Helium for lifting power of balloons.
Take a look at this link about balloons (and lifting underwater).
 
I think we just have to consider that the O2 has mass. and the CO2 has mass. and we have to add that in. when its in that giant balloon. we can consider it to be its own object with a certian mass and a certian size (and extremely low mass). so let's just use 1m^3 volume.

I think the force from the water is going to be 1000 times greater than the weight of the O2 or CO2.
so the type of gas (while under water) has a really small effect.
 
I didn't account for F=ma or drag forces.
 

Similar threads

  • · Replies 70 ·
3
Replies
70
Views
6K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 6 ·
Replies
6
Views
1K
  • · Replies 4 ·
Replies
4
Views
1K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 18 ·
Replies
18
Views
3K
  • · Replies 18 ·
Replies
18
Views
2K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 4 ·
Replies
4
Views
5K
Replies
9
Views
2K