The Response of Pneumatic Transmission Lines to Step Inputs

An equation was derived which describes the pressure-time relationship that occurs at the end of a dead-ended or volume-terminated pneumatic transmission line following a sudden pressure change at its input. The two partial differential equations which are solved are basic for transient fluid flow in pipes and analogous to the equations for transient electric current in lines without leakage. The derivation was based on a one-dimensional uniformly distributed system, small, reversible, adiabatic-pressure changes, and laminar flow. Experimental results obtained from tests on 3/8-in. and 1/4-in. tubing showed good agreement with the theoretical results.