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CONTHOS 3 – TCDProcess Gas Analyzer
Application Questionnaire

The following questionnaire can help to define the analysis boundary conditions for the implementation of an LFE CONTHOS for hydrogen analysis (under certain conditions other gases can be measured as well).

Contact details

Company: / E-mail:
Name: / Phone:
Dept.: / Fax:
Address:

Type of sample gas / application

Biogas / Metallurgy / Chemical / other:
Gas production / Synthesis gas / Petrochemical

Installation site

Installation site / Indoor / Outdoor
Ambient temperature at location / min.:°C / norm.:°C / max.:°C
Hazardous area / Exzone 1 / Exzone 2 / Ex free

Gas composition and characteristics

Please list all relevant gases. Please be sure to list O2 or air if it can also be present in the sample gas during measuring operation.

Component / min.
(vol.%) / normal
(vol.%) / max.
(vol.%) / Analyzer range if measured component
( for potential use in dynamic
interference correction)
Corrosive or toxic components
(e.g. SO3, HF, Cl2, HCl, H2S, NH3 or HCN, COCl2)
min / max / units
Sample gas dewpoint / °C
Sample gas pressure
Sample gas temperature / °C

CONTHOS analyzer version

CONTHOS 3ETCD / CONTHOS 3FTCD / CONTHOS 3F Ex pTCD
Housing version / / /
19” rack housing / Field housing / Field housing for
Ex Zone 1 (and 2)
System protection class: II 2 G, Ex p II T4
Sample gas connectors / for tubing 6mm
for tubing ¼"
NPT-¼" female / for tubing 6mm
for tubing ¼" / Standard: for tubing 6mm
external reducer fittings for tubing ¼"
Housing purge connectors / for tubing 6mm
for tubing ¼" / Inlet:G 3/8"-female
Outlet:G 1"-female
Flame arrestors / external flame arrestors (customer connection NPT-¼" female)
Power supply / Standard: 100-240VAC, 50-60Hz

Desired CONTHOS analyzer range(s)

Begin of range / End of range / Units
(vol.% or ppm) / H2 or other suitable component
Range 1 / to
Range 2 / to
Range 3 / to

Interface options

Digital I/O expansion
8 optically isolated digital inputs
7 floating relay contacts / Serial interface
RS485 with Modbus RTU
Note: The digital I/O module cannot be used in conjunction with the optional serial interface module.

Comments

Technical prerequisites

This questionnaire assumes as a prerequisite that the sample gas and conditions presented to the CONTHOS fulfill the following:

  • The customer must ensure that the sample gas is dry and free of particulates and aggressive components before entering the analyzer. That means an adequate sample handling system is in place.
  • The sample gas dewpoint should at minimum be 10°C below ambient temperature to avoid condensation in the gas lines.
    The normal operating temperature of the CONTHOS TCDdetectorassembly itself is 70C (depending on the application the operating temperature can be chosen from 60 up to 180C.
  • The sample flowrate is between 30 - 60 l/h for optimum performance (min. 3 l/h, max. 120 l/h).
  • The sample gas pressure does not exceed max. 300 mbar over atmospheric pressure.
  • The CONTHOS should not be used for measuring ignitable gas mixtures.
  • The customer must ensure compliance with applicable regulations when using the analyzer with flammable or toxic gases or when installing within hazardous areas.
  • The CONTHOS gas analyzer is available as an explosion protected version and further explosion protection measures maybe requested.

Measuring principle - gas composition

The CONTHOS uses the principle of thermal conductivity. This non-selective principle is ideally suited to binary gas mixtures. The lowest range is 0-0.5vol.%H2inN2 or 99.5 - 100vol.%H2inN2 (or equivalent ).

For gases with multiple components it is necessary to provide information about the species, the concentration and dynamics in order to calculate the individual interferences caused by the different constituents. Furthermore the table can help to provide a basis for defining a reference gas or the selection of a suitable method of interference compensation.

Depending on the constituents and their respective ranges of fluctuation one of the following scenarios for a gas analysis based on thermal conductivity is possible:

  • No further interference considerations necessary.

... or ...

  • The accompanying gases have quasi constant concentrations allowing an interference correction by integration into the instrument calibration thereby helping to minimize errors.

... or ...

  • Under certain circumstances a static interference correction can be implemented. This is accomplished by manually setting the concentration of a particular interfering gas component in a dialog window for the CONTHOS in certain intervals.

... or ...

  • A dynamic interference correction utilizing external selective gas analyzers can be implemented or combined with a static correction facility. The CONTHOS provides 3 input channels.
    Note: Suppressed signal ranges cannot be processed. The input signal level(s) can be either 0-20mA or 4-20mA for each of the channels independent of the others.

... or ...

  • The gas analysis using thermal conductivity is possibly not feasible for low ranges and/or high fluctuation levels of interfering components. This needs to be evaluated case by case depending on min. and max. concentrations of accompanying gases.

LFE GmbH & Co.KGCONTHOS 3-TCDCONTHOS-3-TCD_appq_en_bt.doc
Application Questionnaire12.01.17