Attenuation of Oscillatory Pressures in Instrument Lines

A theoretical investigation has been made of the attenuation and lag of an oscillatory pressure variat ion applied to one end of a tube, when the other end is connected to a pressuresensitive element. An elementary theory based on incompressible viscous-fluid flow is first developed. The elementary solution is t hen modified to take into account compressibili ty; finite pressure amplitudes; appreciable fluid acceleration; and finite length of tubing (end effects). Account is taken of heat t ran sfer into the tube. The complete theory is derived in an appendix. The results are summarized in eight graphs in a form convenient for use in computing the lag and attenuation of a sinusoidal oscillation in a transmission tube.