Pulse damper

Abstract

A pulse damper for use in high-pressure liquid pumping applications such as liquid chromatography comprises a length of flattened polytetrafluoroethylene tubing that can be coupled to the high-pressure liquid flow line. The flattened tubing is enclosed within a liquid-tight housing structure completely filled with a compressible liquid, and the end of the tubing are coupled to the high-pressure flow line by fittings mounted inside the housing structure. When a transient pressure variation occurs in the flow line, the cross-section of the tubing changes from a flattened elliptical configuration to a more rounded configuration as the pressure pulse temporarily overcomes the stresses that tend to maintain the tubing in its flattened configuration. The restoring force of the compressible liquid in the housing structure surrounding the tubing prevents expansion of the tubing beyond a desired limit during a pulse, so that the tubing cannot burst when its cross-sectional configuration changes. The overall length of the tubing, related to the volume and compressibility of the compressible liquid, the highest anticipated pulse pressure in the flow line, and the pre-determined maximum change to be allowed in the average cross-sectional area of the tubing, is generally much greater than the length of the housing structure, and hence the tubing is folded or coiled within the housing structure. Dissipation of the transient energy of a pulse in compressing the liquid in the housing structure effectively damps the pulse.