Instruction Manual

ManualsBrandsYokogawa ManualsAir equipmentGC8000 Process Gas Chromatograph

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App.A-1

IM 11B08A01-01E

Appendix A

Principle of Gas Chromatograph

A gas chromatograph is an analyzer which ﬁ rst sends a ﬁ xed volume of the sampled

multicomponent gas mixture to a column, separates it in the column, then measures the

concentrations of the components with a detector. The process gas chromatograph analyzes

intermittently, allowing periodic analysis by a speciﬁ ed method, thus automatic sampling is

possible.

This chapter explains the measurement principle of the GC8000 Process Gas Chromatograph.

 Sampling Mechanism

The process gas chromatograph consists of a sampling mechanism, a column and a detector.

Sampling is carried out by switching a sampling valve. When separating components or detecting

concentrations, the sampling valve is set to allow the gas (liquid) to be measured to ﬂ ow through

the sample column. When sampling, the sampling valve leads the gas (liquid) to be measured to

a column on a carrier gas. (See Figure1)

There are two important points regarding sampling: a regular volume is sampled since repeated

sampling is required; and samples are taken quickly and securely. The volume is fixed by

measuring a specific gas (liquid) of controlled temperature and pressure using a sample

measurement tube. Samples are taken quickly and securely by ensuring that the gas to be

measured always ﬂ ows without interrupt.

Sample valve

Electric signal

Vent

Measuring tube

Sample

Carrier gas

Column Detector

Component separation and

concentration detection

Status of sampling

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