ABSTRACT
Apparatus uses exponential dilution method to determine range of linear measurement for BTU analysis. Every component measured by the gas chromatograph can be easily checked for both linearity and minimum detectable limits. Gas chromatography is a method by which gas mixtures are physically separated into their individual components and quantified. The dilution flask is set up with an amount of each impurity in natural gas which far exceeds that found in pipeline gas. The on-line or process gas chromatograph performs this function on a continuous basis. On-line BTU measurement of natural gas is accomplished by analyzing eleven components of the gas and determining the BTU content based on the component mixture using appropriate factors. A calibration on a known standard gas of high BTU content and an unknown run using a low BTU standard gas can suffice as a linearity check for individual systems.
