Stability of gas pressure regulators

Gas pressure regulators are widely used in both commercial and residential applications to control the operational pressure of the gas. One common problem in these systems is the tendency for the regulating apparatus to vibrate in an unstable manner during operation. These vibrations tend to cause an auditory hum in the unit, which may cause fatigue damage and failure if left unchecked. This work investigates the stability characteristics of a specific type of hardware and shows the cause of the vibration and possible design modifications that eliminate the unstable vibration modes. A dynamic model of a typical pressure regulator is developed, and a linearized model is then used to investigate the sensitivity of the most important governing parameters. The values of the design parameters are optimized using root locus techniques, and the design trade-offs are discussed.