exhaust valve 34 and a handle 23 which is one possible means to reciprocate the entire pump plunger assembly 18 which fits slidably into the fixed cylindrical plunger guide 17 and is sealed gas tight by the high pressure seal 26 the closed upper ends of the outer sleeve assembly 19 and the inner sleeve assembly 37 are connected to the intake valve 21 and exhaust valve 22 by channels 24 30 and 25 the inner sleeve assembly 37 is comprised of an inner sleeve 32 a connecting bolt 36 containing channel 30 which extends to the channels 24 and 25 cooperating gaskets 38 and 39 which are positioned about the connecting bolt 36 and a flexible membrane 20 a lower flexible membrane 48 cooperating gaskets 40 and 41 and plate 42 connecting screws 43 detachably secure plate 42 flexible membrane 20 lower flexible membrane 48 and gaskets 40 41 to the lower end of the inner sleeve 32 the connecting bolt 36 detachably secures the inner sleeve assembly 37 to the outer sleeve 19 referring further to the inner sleeve assembly 37 the flexible membranes 20 and 48 within a vertical channel 28 form two distinct free interior volumes or chambers 44 and 45 which completely contain the fluids or gases within them the chamber 44 is charged with fluid or gas 35 by means of the charging valve 33 and channel 46 and the fluid or gas is exhausted by means of the channel 47 and the exhaust valve 34 the flexible membranes 20 and 48 may be composed of any suitable material and may be of any predetermined shape to form distinct free interior volumes or chambers with flexible walls within the vertical channel 28 of the pump plunger assembly 48 which completely contain the fluids.