1-Combustion

Dumatherm - Setting a new dimension in Nitrogen Determination

 

This combustion method has already been developed at 1848 by Dumas. In the Dumas method, a sample is burned in an oxygen rich atmosphere at high temperatures and the resulting gases are analyzed. Now, C. Gerhardt, being the market leader for the Kjeldahl analysis, can also offer a highly efficient instrument with the DUMATHERM. By using the Dumas method, this new technique offers a fast and comfortable alternative to the classic systems.

 

The new DUMATHERM comprises all advantages of the Dumas- method: It is fast, precise, cost efficient as well as saving costs! The clever design of the furnace chamber in combination with the direct analysis of all resulting gases provides the user with results within 2-3 minutes. Thanks to the construction of the instrument, the DUMATHERM has hardly any wear- and -tear parts, which reduces costs for service significantly.

Control

DUMATHERM is entirely controlled via PC and the user friendly control software Dumatherm-Manager. Since the entire analysis is controlled by software, the amount of time that the user has to actually spend in front of the instrument, is reduced to a minimum. Furthermore, the software includes very powerful diagnosis and documentation functions, which facilitate an effective interpretation of the data.

Dumatherm Principle

Principle of analyses
Solid or liquid samples are combusted at high temperatures in the presence of catalysts into oxides. With the help of copper, the resulting nitrogen oxides (NOx) are reduced to elemental nitrogen while the by-products water and carbon dioxide are separated completely. The remaining nitrogen is analyzed using a single filament detector.

Analysis procedure

The samples drops from the autosampler (AS) into a purge chamber, which is constantly purged with helium. The combustion is initiated by switching the gas flow to oxygen and the transport into the 1000 °C hot, upright combustion furnace (LF). The ashes are collected in a quartz tube insert, which can be easily taken out and exchanged - even when the unit has reached operating temperature. Among all resulting combustion products (CO2, H2O and N-oxides), the nitrogen oxides react in the reduction furnace (RF) to elemental nitrogen (N2). The majority of the water is separated using an intelligent Nafion® tube membrane system (F1), which works using a semipermeable wall in the counter flow. Any remaining amounts are caught in an absorption trap (F2), where the separation of CO2 is done in self-regenerating absorption traps (F3). Elemental nitrogen remains, which is measured in a thermal conductivity detector (TCD) without any reference gasflow.

Model DT

Sample Sizes:

 

0.5 mg - 1 g depending on the type of sample

Sample capacity:

 

autosampler with 40, 80, or 120 positions

Duration of analysis:

 

2-4 minutes depending on the sample type and sample size

Percentage recovery:

 

>99,5 %

Detection limit:

 

<0,01 mg N

Standard deviation:

 

<0,5 %

Operation:

 

via PC using the control software Dumatherm-Manager:
- Statistics and diagnosis function
- Individual and serial print outs of the results
- Extensive possibilities for documentation

Temperature combustion furnace:

 

400 - 1100 °C

Temperature reduction furnace:

 

400 - 1100 °C

Temperature desorption furnace:

 

50 - 350 °C

Required gases and quality:

 

- Helium quality grade 5.0 (99.999 %)
- Oxygen quality grade 5.0 (99.999 %)
- Compressed air or nitrogen (99.6 %, free of oil / water)

Inlet pressure helium:

 

3 - 6 bar

Inlet pressure oxygen:

 

3 - 6 bar

Inlet press. compr. air or nitrogen:

 

4 bar

Ambient temperature:

 

15 °C < t < 35 °C

Nominal voltage:

 

230 V AC, 50 / 60 Hz

Dimensions (W x D x H):

 

800 x 370 x 500 mm / 625 mm with autosampler

Weight:

 

65 kg

Nominal wattage:

 

max. 6 Ampere

Digital balance:

 

optional

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