You have a 1" diameter steel pump 12 " high vertical in a 2 ton hydraulic press connected to you chamber below. Check valve, cut off valve etc.
Fill the pump/chamber to 600 psi with you a/c compressor.
(see my post on pressure assisted a/c compressor)
Use the hydraulic press to push the piston down to the bottom with 4,000 pounds of force
These pumps are under $20 at Harbor Freight..
Depending upon the volumes and diameters involved, your chamber will be filled at much higher pressure than 600 psi.
