An inflatable evacuation slide has a pressure relief valve in at least one of the inflatable support tubes. The pressure relief valve has a "floating" lifter that slidingly engages the valve stem of the poppet valve portion of the pressure relief valve. Because the lifter floats on the valve stem, the lifter cannot load the poppet valve in compression. When the poppet valve opens, however, air pressure acting on the lifter causes the lifter to engage a stop at the end of the valve stem, which enables the lifter to fully open the poppet.