Teledyne GFC 7001EM Pneumatic Operation, Internal Pneumatic Flow Basic Configuration

Theory of Operation Model GFC7001E Carbon Dioxide Analyzer

11.3.PNEUMATIC OPERATION

CAUTION

GENERAL SAFETY HAZARD

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 12-1.

Procedures for correctly performing leak checks can be found in Section 12.3.3.

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.

INSTRUMENT CHASSIS

GFC Motor Heat Sync

GFC Wheel

Housing

SAMPLE

PRESSURE

SENSOR

FLOW

SENSOR

Sample Gas

Flow Control

Figure 11-7: Internal Pneumatic Flow – Basic Configuration

Teledyne Analytical Instruments 234