Patent ID: 7598494

Claim:
A system for certifying to a user a concentration of gas in a cylinder comprising: a gas cell configured to receive a sample gas from a cylinder, an FTIR (Fourier Transform Infrared) spectrometer coupled to the gas cell for scanning the sample gas and forming a beam spectrum, a processor coupled to the FTIR spectrometer for calculating an intensity response of the sample gas based on the beam spectrum, a storage device for storing data points of a plot of intensity response of a known gas versus concentration levels, wherein the processor is configured to interpolate between the stored data points of the plot to determine an interpolated data point corresponding to a resultant intensity response of the sample gas, and provide to the user a concentration level of the sample gas based on the interpolated data point, the gas cell configured to receive a standard gas from a cylinder and a zero gas from another cylinder, the FTIR spectrometer configured to scan the standard gas and the zero gas, and the processor configured to calculate an intensity response of the standard gas and an intensity response of the zero gas, wherein the intensity response of the sample gas is Xn, the intensity response of the standard gas is Yn, and the intensity response of the zero gas is Zn, and the resultant intensity response of the sample gas is based on the following equation: Rn = ( Ya Yn - Zn ) ⁢ Xn - ( Ya Yn - Zn ) ⁢ Zn where: Xn is the sample intensity response, Yn is the standard intensity response, Ya is the actual value of the standard gas provided as an input value by the user, Zn is the zero intensity response, n is a scan number (n is 1 or greater), and Rn is the resultant intensity response of the sample gas.