A method for estimating at least one flow of a gas in an enclosure maintained in a low pressure regimen relative to this gas, the low pressure regimen being maintained permanently such that the change over time of the partial pressure of the gas within the enclosure thus corresponds to a balance between a system making this low pressure regimen, which is stable, and that a measure of the change of the partial pressure of the gas in the enclosure corresponds and enables to obtain the flow of the gas in the enclosure , the method comprising at least: - measuring , as a function of time, a gas flow J mesure in the enclosure maintained in a low pressure regimen relative to the gas, and - estimating (102.3 - 102.6, 106) values of parameters A and B iteratively implemented by decreasing an estimation error based on a difference between an estimation of the gas flow J estim (t) and the measured gas flow J mesure , wherein, when the measured gas flow J mesure corresponds to a pressure rise of the gas in the enclosure, the estimation of the gas flow J estim (t) is calculated according to the equation: J estim t = 2 A ∑ n = 1 n max B π t − OffX 1 2 exp − 2 n + 1 2 4 B t − OffX + OffY and when the measured gas flow J mesure corresponds to a pressure decrease of the gas in the enclosure, the estimation of the gas flow J estim(t) is calculated according to the equation: J estim t = P init − 2 A ∑ n = 1 n max B π t − OffX 1 2 exp − 2 n + 1 2 4 B t − OffX + OffY with OffX and OffY: relative integers whose values are constant during the estimating of parameters A and B ; P init : first measured value of the gas flow J mesure ; n max : integer higher than or equal to 1; wherein estimating the values of the parameters A and B includes at least the implementation of the following steps of: a 1 ) choosing (106.1) initial values of the parameters A and B; b 1 ) calculating (106.2) the estimation of the gas flow J estim (t); c 1 ) calculating (106.3) the estimation error; d 1 ) when the estimation error is positive, decreasing the value of the parameter A and/or the value of the parameter B, and when the estimation error is negative, increasing the value of the parameter A and/or the value of the parameter B (106.4); and wherein the implementation of steps b 1 ) to d 1 ) is successively repeated several times until a stabilization of the estimated values of the parameters A and B (106.5) is achieved. - measuring , as a function of time, a gas flow J mesure in the enclosure maintained in a low pressure regimen relative to the gas, and - estimating (102.3 - 102.6, 106) values of parameters A and B iteratively implemented by decreasing an estimation error based on a difference between an estimation of the gas flow J estim (t) and the measured gas flow J mesure , a 1 ) choosing (106.1) initial values of the parameters A and B; b 1 ) calculating (106.2) the estimation of the gas flow J estim (t); c 1 ) calculating (106.3) the estimation error; d 1 ) when the estimation error is positive, decreasing the value of the parameter A and/or the value of the parameter B, and when the estimation error is negative, increasing the value of the parameter A and/or the value of the parameter B (106.4); and wherein the implementation of steps b 1 ) to d 1 ) is successively repeated several times until a stabilization of the estimated values of the parameters A and B (106.5) is achieved. <EOS>