Apparatus for compressing a gas

A lubricant piston and cylinder gas pressurizing assembly, comprising:

• a substantially vertically oriented cylinder body having a top wall and a longitudinally extending bore with an inner wall;
• a substantially vertically oriented piston adapted for reciprocating motion in said cylinder bore, said piston including a piston head with a top end and a bottom end, a piston rod being secured to said piston head bottom end, said piston head top end having a substantially horizontally oriented top face;
• a seal groove extending around a periphery of said piston head and spaced from said piston head top face;
• a plurality of spaced fluid conducting grooves extending along said periphery of said piston head from said piston head top face to said seal groove;
• an annular primary seal member positioned in said seal groove and having an outer face, adapted to contact said cylinder wall, and an inner face;
• an annular resilient backup seal member positioned in said seal groove radially inwardly of said primary seal member and adapted to contact said inner face thereof as well as at least two walls of said seal groove;
• a pool of a lubricant provided on said piston head top face;
• refill means for allowing additional lubricant to be added on said piston head top face;
• inlet means for allowing a gas to enter said cylinder above said piston;
• and,
• movement means for actuation of said piston upwardly to compress said gas and pressurize said lubricant, a portion fo said pressurized lubricant flowing through said fluid conducting grooves and into said seal groove to compress said backup seal member and thereby urge said primary seal member outer face against said cylinder inner wall.