Dampeners that attenuate pressure pulsation by use of a liquid to gas to liquid "phase change", or "release from solution". Dampeners that cause the distance between point of pressure pulse wave entry and point of exit to be a huge multiplicity of distances. And, dampeners that accelerate the velocity of the pressure wave, increasing its amplitude, then destroy the wave by exploding it into a chamber, within which chamber the distance to any reflection point is so great that the amplitude is decreased to an acceptable level.