Fire Safety Science Digital Archive

Pneumatic tube type heat sensitive fire detectors are used in several different applications, e.g. the protection of road tunnels. Some quantitative knowledge in the dynamic performance of these systems is essential for the prediction of response times under different operating conditions or for the calculation of a suitable response threshold setting. The paper discusses an approximative method to calculate the dynamic performance that takes into account the inherent nonlinearities of some system elements. The method is based on some simplifying assumptions and uses models for all system elements. The simplification results in an approximative overall model for the pneumatic system which can be described by a fairly simple nonlinear differential equation. This equation can be solved by using a suit - able Runge-Kutta method and yields the pressure difference ?p at the pneumatic switch as a function of time. It is shown furthermore that this solution cannot be considered as valid in general but can be used as a calculation tool for response times and response behavior of the system in the range of normally used response pressure thresholds with a suitable accuracy. So the method is simple enough and usable for practical purposes.