TCD Gas Chromatograph

Principle

Changes in thermal conductivity, such as when organic molecules displace some of the carrier gas, cause a temperature rise in the element which is sensed as a change in resistance.

Response in universal and proportional to concentration

Best gases for TCD Gas Chromatograph : H2 or He. Because of highest thermal conductivity (0.170 and 0.141 J/(K.m.s), respectively, to be compared with N2 0.024 J/(K.m.s) for N2).

For Helium and Hydrogen the temperature conductivity lowers when solute is eluted. The sensitivity is inversely proportional to flow rate: the detector is more sensitive at lower flow rates.

Detection limit: < 5 ppm

To increase sensitivity, the temperature of the block should be maintained at lowest temperature that allows all the solutes remain gaseous.

Some Global References

Company	Type of analyser	Analyser	Measurement
Air Products (Scotland)	Mixture	TCD	O2 (ppm % ), CO2 (%)
Air Products (Poland)	Mixture	TCD	O2 (ppm %), CO2 (%), Ar (%), H2O (%)
Air Liquide (France)	Mixture	TCD	O2 (%), N2 (%), He (%), CO2 (%), Balance Ar (%)
Air Liquide (Denmark)	/	TCD	N2 (%) ASSAY

Type of configurations

DID Gas Chromatograph - 500

Process Line

This new line 500 has been designed for stand alone operation. Easy configuration and quick start-up make this new system ideal for process gas analysis.

In addition to its user-friendly interface (touch screen display), the new line 500 has its own chromatographic software that allows the concentration of each impurity to be displayed directly. Moreover, the new line 500 can be remotely controlled through Ethernet or Internet.

DID Gas Chromatograph - 600

Laboratory Line

The new line 600 has been designed for working with Chromdyne software on a computer. It make this new system ideal for laboratory process gas analysis. Moreover, the new line 600 can be remotely controlled through Ethernet or Internet.

Technical specifications

Accuracy	Depend of the range used
Drift	1 % over 24 hours
Temperature drift	1 % per degree
Operating temperature	± 20°C without wide variations of temperature
Sampling gas	N2, H2, O2, Ar, He, Air, CH4 , CO, CO2
Sample gas connection	1/8’’ Swagelok SS
Sample flow rate	Approximately 3 to 5 l/h
Sample pressure	< 100 mBar
Carrier gas	All gases, except corrosives ones
Carrier gas connection	1/8’’ Swagelok SS
Carrier gas pressure	7 bar
Carrier gas fl ow rate	4 l/h
Recommended quality	minimum 5.5
Power supply	220 Vac, 50-60 Hz
Power consumption	500 VA
4-20 mA output	Eight configurable outputs depending on the application
RJ-45 connection	Computerised system maintenance
Output relays (SPST 2 amperes / 250 Vac)	1 Analyser Failure Alarm contact 1 Alarm High contact 1 Alarm High High contact

5 ppm resolution guaranteed

User-friendly interface

Fast response time

Adjustable alarm and oven settings

CE marked

Possibility of auto-calibration programming

Chromdyne software