Teledyne 4060 User Manual download pdf (Page 19)

Series 4060 Operational Theory

Teledyne Analytical Instruments 19

Operational Theory

2.1 Introduction

Series 4060 Analyzer for Benzene uses a FID detector and a Gas

Chromatograph (GC) Column. Using a carrier gas and a microprocessor

actuated switching valve, a fixed volume of sample is pushed into the

Column maintained at a constant temperature. The eluted gas is

analyzed for benzene in a FID detector and the column is back flushed

to accept the fresh sample in the next cycle. Actual separating and

detecting sequence may vary depending on compounds of interest in the

application for which the analyzer is configured.

The Series 4060 Analyzer uses a flame ionization detector to sense

benzene. 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. Also considering the fact that the

required sensitivity of 100 ppb full scale was achieved, FID was

considered a better choice over the limited life and less reliable Photo

Ionization Detector.

A stainless steel packed column containing Chromosorb Diatomite

was used at a constant temperature of 70 C. Using nitrogen as a carrier

gas and a 5 ml sample loop, benzene elutes from the column within a

few minutes. Additionally, a clear separation is observed from other

aromatic hydrocarbons, namely toluene, ethyl benzene, and xylenes. The

actual temperature setpoint and compound separation for your

instrument may be different depending on the application. It is listed in

the Addendum and Testing Results section of Appendix B.

2.2 Modes of Operation

The analyzer has 2 modes of operation depending on the position of

the GC Sampling Valve (See Piping Diagram in Figure 2-2). They are:

Sample Mode (position A) and Analysis Mode (position B).

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Teledyne 4060 User Manual Page 19