Introduction - Teledyne 4040 Instruction, Operating And Maintenance Manual

Operational Theory
Operational Theory

2.1 Introduction

The sample is brought to sample loop and a 10-port switching valve
kept inside a heated (Temperature: 50° - 80° C per application)
SAMPLE Chamber. Using a carrier gas and a microprocessor actuated
switching valve, a fixed volume of sample collected in the Sample Loop,
is pushed into the Column maintained at a constant temperature. The
eluted gas is analyzed for methane in a FID detector. Immediately, at
the end of the analysis of methane, the Valve is switched to reverse the
flow through the Column, causing propane as NMH to elute and be
analyzed.
Series 4040 uses a Flame Ionization Detector to sense hydrocarbons.
The FID was selected based on the positive performance and extensive
experience in the use of this detector in other Teledyne analyzers namely
Model 402R and Model 4020. The FID has proven itself to be a rugged,
stable, long life sensor giving years of trouble free operation in various
applications.
A packed Column was used at a constant temperature to separate
methane 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 for
the analysis of the methane content of the hydrocarbons.
2) Non-methane Mode (POSITION A)
During this mode, the FID detector is monitoring Non-methane
hydrocarbons, such as propane. At the end of the cycle, the methane
content of the sample (from Position B) is added to the NMH value
to compute THC values.
Teledyne Analytical Instruments
Series 4040
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