High pressure chamber using PVC
Posted: Fri Jun 15, 2007 3:04 pm
Everything we talk about here is gage pressure, which is relative to surrounding pressure (usually 1 atmosphere) rather than the absolute pressure.
All the numeric values I use for this example are just made up to give you the basic idea of what I am saying.
It is safe to say that a sealed piece of PVC rated for 100 PSI will explode when 200 PSI is pumped into it. Say you were able to surround that piece of PVC with 100 PSI air, it would be equivalent to filling that chamber to 100 PSI under normal conditions, or if the outside conditions were 200 PSI, the chamber material would experience a net pressure of 0 PSI.
Using multiple chambers contained within each other, it could be possible to achieve unrealistically high absolute pressures, I have created a diagram that shows the basic concept using two chambers.
Before anyone goes and tries this, here is a warning. Using many chambers to sequentially step down from the pressure in the main tank may look good when you imagine the inner chamber containing its maximum pressure, but you must also look into what could happen when the inner chamber is empty. We are familiar with pipe explosions here, but we know almost nothing about implosion.
Worst case scenario: your inner chamber collapses causing a massive pressure drop in your second chamber causing it to implode and so on, the combined high pressure gases from imploding chambers could lead to explosion of the outer tank if the combined pressure of the contained gases exceeds the rating of the outermost wall of PVC, possibly by a large amount. This could result in an explosion.
The probably of such a situation is not high (hopefully impossible), just be careful when delving into new concepts especially since there is little information concerning subjecting PVC pipes to negative pressure.
All the numeric values I use for this example are just made up to give you the basic idea of what I am saying.
It is safe to say that a sealed piece of PVC rated for 100 PSI will explode when 200 PSI is pumped into it. Say you were able to surround that piece of PVC with 100 PSI air, it would be equivalent to filling that chamber to 100 PSI under normal conditions, or if the outside conditions were 200 PSI, the chamber material would experience a net pressure of 0 PSI.
Using multiple chambers contained within each other, it could be possible to achieve unrealistically high absolute pressures, I have created a diagram that shows the basic concept using two chambers.
Before anyone goes and tries this, here is a warning. Using many chambers to sequentially step down from the pressure in the main tank may look good when you imagine the inner chamber containing its maximum pressure, but you must also look into what could happen when the inner chamber is empty. We are familiar with pipe explosions here, but we know almost nothing about implosion.
Worst case scenario: your inner chamber collapses causing a massive pressure drop in your second chamber causing it to implode and so on, the combined high pressure gases from imploding chambers could lead to explosion of the outer tank if the combined pressure of the contained gases exceeds the rating of the outermost wall of PVC, possibly by a large amount. This could result in an explosion.
The probably of such a situation is not high (hopefully impossible), just be careful when delving into new concepts especially since there is little information concerning subjecting PVC pipes to negative pressure.