Method for detecting and quantifying obstructions in a gas network under pressure or vacuum; the gas network comprising: - one or more sources of compressed gas or vacuum; - one or more consumers, consumer areas of compressed gas or vacuum applications; - pipelines or a network of pipelines to transport the compressed gas or vacuum from the sources to the consumers, consumer areas or applications; - a plurality of sensors (9a, 9b) which determine one or a plurality of physical parameters of the gas at different times and locations in the gas network; wherein the method comprises the following phases: - a baseline or zero phase determining an initial physical model or mathematical relationship between measurements from a first group of sensors (9a, 9b) and a second group of sensors (9a, 9b) based on physical laws using estimation algorithms; - an operational phase in which the physical model or mathematical relationship between the measurements of the first group of sensors (9a, 9b) and the second group of sensors (9a, 9b) is re-established at regular time intervals by means of estimation algorithms to predict gas network obstructions; wherein the operational phase comprises the following steps: - reading out the first group and second group of sensors (9a, 9b, 9c); - re-estimating, determining or calculating the physical model or mathematical relationship on the basis of the read measurements from the sensors (9a, 9b,9c); - determining or calculating of the existence of an obstruction in the system based on the difference and/or its derivatives between the parameters of the physical model or mathematical relationship as determined during the baseline or zero phase and the operational phase; - generating an alarm and/or generating a degree of obstruction and/or generating the corresponding obstruction cost if an obstruction is detected wherein the aforementioned physical model or mathematical relationship takes the form of a matrix of parameters or constants, wherein the modifications of these parameters or constants are being monitored during the operational phase. - one or more sources of compressed gas or vacuum; - one or more consumers, consumer areas of compressed gas or vacuum applications; - pipelines or a network of pipelines to transport the compressed gas or vacuum from the sources to the consumers, consumer areas or applications; - a plurality of sensors (9a, 9b) which determine one or a plurality of physical parameters of the gas at different times and locations in the gas network; - a baseline or zero phase determining an initial physical model or mathematical relationship between measurements from a first group of sensors (9a, 9b) and a second group of sensors (9a, 9b) based on physical laws using estimation algorithms; - an operational phase in which the physical model or mathematical relationship between the measurements of the first group of sensors (9a, 9b) and the second group of sensors (9a, 9b) is re-established at regular time intervals by means of estimation algorithms to predict gas network obstructions; - reading out the first group and second group of sensors (9a, 9b, 9c); - re-estimating, determining or calculating the physical model or mathematical relationship on the basis of the read measurements from the sensors (9a, 9b,9c); - determining or calculating of the existence of an obstruction in the system based on the difference and/or its derivatives between the parameters of the physical model or mathematical relationship as determined during the baseline or zero phase and the operational phase; - generating an alarm and/or generating a degree of obstruction and/or generating the corresponding obstruction cost if an obstruction is detected