Within an apparatus for storing a liquid, there is first included a storage tank. The storage tank has formed integral thereto and in fluid communication therewith a liquid inlet port and a liquid outlet port. The storage tank also has formed integral thereto and in fluid communication therewith a gas inlet port and a gas outlet port. Finally, the gas outlet port has connected thereto and in fluid communication therewith a floating plug valve. The floating plug valve comprises a first plug movably positioned over and sealing a first aperture within the floating plug valve such that a first weight of the first plug and a first area of the first aperture define an upper operating pressure of a gas introduced into the storage tank through the gas inlet port. The apparatus of the present invention also contemplates a floating plug valve employed within the apparatus of the present invention.
