In a sealed container (plastic bottle filled with water and applied a cap). The container has a fitting. Would that be a pressure different inside the container, if I used air to provide 10 psi through the fitting and maintain this pressure, vs I used water to pump into the container to maintain at 10 psi?
Will there be a pressure difference inside a sealed container?
- Posted:
- 3+ months ago by UncleSpider
- Topics:
- water, inside, bottle, plastic, different, container, pressure
Details:
Added 3+ months ago:
I should re-phrase my question:
We have two sealed containers with fitting, both filled with water.
One container is pressurized by air through the fitting. When the supply air pressure reaches 10 psi, we maintain this pressure for 20 minutes.
The other container is pressurized by water through the fitting. When the supply water pressure reaches 10 psi, we maintain this pressure for 20 minutes.
Here are my questions:
a) Will the pressure be the same inside both containers.
b) Will the volume expansion be the same, or difference between the two containers. The bottles are plastic and the material is stretchable when the container is pressurized.
c) Which one may have more chance to leak?
Responses (2)
I believe you are talking about the difference between hydrostatic pressure vs air pressure.
Both water and air and water are fluids — they can flow from one place to another.
The difference is that water is an incompressible fluid — its density is almost constant as the pressure changes — while air is a compressible fluid — its density changes with pressure.
Hydrostatic pressure is the pressure exerted by an incompressible fluid (a liquid) at a given point, due to the weight of the fluid above it.
www.cyberphysics.co.uk
Interestingly enough I do some pressure testing at work of precision investment casting used in the aviation industry. Fuel transfer pumps to be exact. We test some cavities with compressed water, these are considered to be high pressure tests 160psi for 20 minutes. And we check with air pressure @20psi for 5 minutes under water in other cavities.
I believe the pressure difference inside of your bottles and the force exerted on the containers will have different pressures based on the simple deduction that the definition of the scale in which the measurements are recorded are different.
( hydrostatic pressure & air pressure )
I could be wrong.
Have a good one.
Hi Casino,
I just re-phrase my question. You point out a very important point. The density of the water is almost constant as the pressure change and air is different.
Please review my re-phrase question and let me know your opinion.
Thanks