Air pressure over water pressure? 1

[enzo2015]

Hi,
I tried posting this question elsewhere, but no one there answered, so I'd like to try here(maybe this is more suitable forum) if it's OK

This is what I want to do:
Air tank holds 6 cubic feet of air at 3000 PSI going through a two stage regulator, first at 3000 PSI, and out of regulator at 130 PSI, then through a 3 way valve just after the regulator into a water tank that hold 2 liters. In the water tank there is another valve that opens and lets the water out(about 1 oz. each time valve opens) pushed by the air pressure. After that valve closes again, another valve connected to a water supply opens and fills the water tank the 1 oz. that was let out, and the air pressure that was used for pressure is sent back out of the water tank through the other side of the 3 way valve near the regulator, and through a vent.
My question is how many times can the 6 CF tank of air push this water out in the 1 oz. amount before it is not able to push the 130 PSI ? I'm confused if the compressed air loses something to the water?
One more detail, the water in the tank is about 100F

Any help would be greatly appreciated....

 

[hydromech]

enzo...
The air pressure will not lose anything to the water.

The air pressure will always remain above the water and apply even pressure across the surface of the water.

The number of times 1 oz of water is forced out of the tank will partly depend on the external pressure or the pressure of the environment into which the 1 oz of water is being forced.

Water will be forced out of the water tank as long as the air pressure is equal to or greater than the external pressure.

The other controlling factor is the amount of water in the tank. The more water there is, the less air there is and the greater the drop in pressure every time 1 oz of water is forced out.

When you know the volume of water, you can work out the amount of air at a given pressure using Boyles law...simply put, Boyles law is P1 X V1 = P2 X V2.

P1 = Starting Pressure 130 PSI
V1 = Starting Volume 6 Cu FT + 2ltr - volume of water.
P2 = Secondary Pressure External Pressure
V2 = Secondary Volume ? No. of 1oz "squirts" in Cu Inches

As long as the temp stays at 100F it will be isothermal and can be ignored.

You should be able to work out the number of op's using this information...that is after you have converted the 1oz weight of the water into volume...

Regards

Hydromech
Hydraulic Systems Engineer

 

[enzo2015]

Thanks, very helpful