4040 - Methane / Nonmethane analyzer - Teledyne Analytical ...

Operational Theory Series 4040Operational Theory2.1 IntroductionThe sample is brought to sample loop and a 10-port switching valvekept inside a heated (Temperature: 50° - 80° C per application)SAMPLE Chamber. Using a carrier gas and a microprocessor actuatedswitching valve, a fixed volume of sample collected in the Sample Loop,is pushed into the Column maintained at a constant temperature. Theeluted gas is analyzed for methane in a FID detector. Immediately, atthe end of the analysis of methane, the Valve is switched to reverse theflow through the Column, causing propane as NMH to elute and beanalyzed.Series 4040 uses a Flame Ionization Detector to sense hydrocarbons.The FID was selected based on the positive performance and extensiveexperience in the use of this detector in other Teledyne analyzers namelyModel 402R and Model 4020. The FID has proven itself to be a rugged,stable, long life sensor giving years of trouble free operation in variousapplications.A packed Column was used at a constant temperature to separatemethane from the remaining non-methane hydrocarbons.The analysis has 2 modes: Methane Mode and Non-methane Mode.1) Methane Mode (POSITION B)In this mode, the eluted sample from the column is fed to the FID forthe analysis of the methane content of the hydrocarbons.2) Non-methane Mode (POSITION A)During this mode, the FID detector is monitoring Non-methanehydrocarbons, such as propane. At the end of the cycle, the methanecontent of the sample (from Position B) is added to the NMH valueto compute THC values.Teledyne Analytical Instruments 17