Jerry, the liquid fill surrounds the entire internal mechanism of the gauge, and the viscous fluid damps the vibration of the bourdon tube, the linkage from the bourdon tube to the needle and the needle itself. As Denny points out, another approach when one is dealing with a pulsating pressure is a pulsation dampner. Often, in severe services like a fluid pump discharge pressure the answer is both, a pulsation dampner to chop the highs & lows, and liquid fill to dampen the result. It is not a question of "fixing" the pulsation. The pulsation in a fluid pressure is there because of the process, not something wrong to be "fixed". With that, I'm done.