Abstract: A piston pressure regulator has a body, a corresponding piston, and a floating seal. The body includes an interior piston cavity, a low pressure port connected with the piston cavity, and a high pressure port connected with the piston cavity. Further, the piston cavity has a length. The corresponding piston is located in the piston cavity and cooperates with the piston cavity to define low pressure and high pressure portions of the piston cavity and low pressure and high pressure sides of the piston. The piston also slides along the piston cavity length, between the low and high pressure ports. The seal is a wafer member that is interposed between the piston and the high pressure port. The seal is separate from each of the piston and the high pressure port to "float" between the piston and the high pressure port. Seals of different thicknesses may be substituted to adjust the operating pressure.