Teledyne gfc 7000ta operation manual Pneumatic Operation

Theory of Operation Model GFC7000TA Carbon Dioxide Analyzer

9.2. Pneumatic Operation

CAUTION

It is important that the sample airflow system is both leak tight and not pressurized

over ambient pressure.

Regular leak checks should be performed on the analyzer as described in the

maintenance schedule, Table 9-1.

Procedures for correctly performing leak checks can be found in Section 9.3.3.

An internal pump evacuates the sample chamber creating a small vacuum that draws sample gas into the analyzer. Normally the analyzer is operated with its inlet near ambient pressure either because the sample is directly drawn at the inlet or a small vent is installed at the inlet. There are several advantages to this “pull through” configuration.

∙By placing the pump down stream from the sample chamber several problems are avoided.

∙First the pumping process heats and compresses the sample air complicating the measurement process.

∙Additionally, certain physical parts of the pump itself are made of materials that might chemically react with the sample gas.

∙Finally, in certain applications where the concentration of the target gas might be high enough to be hazardous, maintaining a negative gas pressure relative to ambient means that should a minor leak occur, no sample gas will be pumped into the atmosphere surrounding analyzer.

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