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Biogas Analyzer for inline measurement in the process flow

The Biogas analyzer from Archigas GmbH (TCD3000 SiA and TCD3000 Si models) is a core component of the Continuous Biogas Monitoring System for methane- and CO₂-containing gas mixtures at biogas plants and organic waste processing facilities.
The analyzers are installed directly in the process line, need no gas pre-treatment, withstand trace concentrations of H₂S and run reliably at humidity levels up to 100 % RH. They deliver continuous inline measurement across ranges from 0–0.5 to 0–100 vol.% at pressures of 0.9–200 barg. Sensing element response time is ≤30 ms. A built-in sintered metal filter protects the sensing element.

In brief: what matters about Archigas gas analyzers for biogas

TCD3000 Si and TCD3000 SiA are compact gas analyzers installed directly in the process line. They are a more cost-efficient alternative to a gas chromatograph for continuous monitoring, tolerate trace concentrations of H₂S and can serve as the measuring component of a biogas monitoring system. Main applications: methane emissions monitoring, methane quality control, raw biogas analysis, methanation.
Archigas gas analyzers for biogas
Send us your gas mixture composition, measuring range, pressure, temperature and a description of the installation point. Archigas specialists will assess whether the TCD3000 SiA or TCD3000 Si suits your specific gas matrix and process task.
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Why choose Archigas as a biogas analyzer manufacturer

Archigas GmbH develops industrial gas analysis equipment built for real process conditions, including biogas production. The company consistently expands its gas analytics portfolio and invests in new measurement solutions.
Archigas designs draw on over 40 years of experience in MEMS sensor technology, deep gas analysis expertise and long-standing cooperation with research institutions. Manufacturing in Germany follows ISO 9001:2015 requirements, which ensures quality control at every production stage.
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Biogas Analyzer Solution TCD3000 for reliable in‑line gas analysis

Biogas analyzer solutions TCD3000 by Archigas are designed to measure binary and quasi-binary gas mixtures in biogas applications. The series comprises two models – the TCD3000 SiA for hazardous areas (ATEX Zone 1) and the TCD3000 Si for standard industrial and laboratory installations. Both versions measure in real time directly in the process stream and are supplied factory-calibrated for the specific gas composition and process conditions. Both models are rated IP66/IP68 to EN 60529.
TCD3000 SiA
For industrial installations in hazardous areas requiring ATEX Zone 1 protection (II 2 G Ex db IIC T4/T3 Gb)
Specification
Archigas TCD3000 SiA hydrogen gas analyzer
TCD3000 Si
For standard industrial areas, laboratories, pilot and R&D installations
Specification
Archigas TCD3000 Si helium leak detector, product photo

Technical specifications of TCD3000 analyzers for biogas measurement

Parameter
TCD3000 SiA
TCD3000 Si
Sensing element response time
30 ms
T90
< 1 s
Warm-up time
< 1 min
Minimum measuring range
0–0.5 vol.%
Maximum measuring range
0–100 vol.%
Number of ranges
10
Analog output
4–20 mA
Serial interface
RS485
Power supply
24±25% VDC, <5 W
Gas connection
G 1/2″ or NPT 1/2″
Ambient temperature
−40…+90 °C / +120 °C
−40…+80 °C
Process gas temperature
−40…+90 °C / +125 °C
−40…+80 °C
Process gas pressure
0.9–200 barg
Gas flow rate
0–10 m/s
Process gas humidity
up to 100 % RH
Protection class
IP66/IP68
Weight
740 g
440 g
Service life
Up to 10 years

TCD technology for biogas analysis

The TCD principle is based on thermal conductivity measurement

The method works well for binary and quasi-binary media where the thermal conductivity of the target gas (H₂, for example) differs markedly from that of the background gas (CH₄ or CO₂). TCD is a non-selective method, though: it measures the thermal conductivity of the entire gas mixture. The background gas composition therefore has to be known or reasonably predictable.

The TCD3000 is designed primarily for binary and quasi-binary gas mixtures

Where known additional components are present in the gas, their effect on the thermal conductivity signal can be determined and compensated through individual cross-sensitivity correction for the given process conditions. In biogas and methanation applications this approach works for the additional components O₂, N₂ and H₂S.

Biogas analyzer TCD3000 resistant to trace concentrations of H₂S

Because it tolerates low hydrogen sulphide levels, the TCD3000 can be used as an H₂S-resistant biogas analyzer for continuous monitoring of target components in suitable gas mixtures. No separate H₂S version of the TCD3000 Si or TCD3000 SiA is required.
Important: prolonged exposure to H₂S may shorten sensor life compared with operation in a sulphur-free gas mixture. The maximum permissible H₂S concentration for long-term continuous operation has to be assessed for the specific application.
Prior to delivery, Archigas can perform factory setup and calibration for your specific gas mixture and process conditions.
Request a technical application assessment

Measurement directly in the process stream

TCD3000 series Biogas Analyzer units are installed directly in the process stream and, under suitable conditions, require no sampling or sample conditioning system. The gas stays inside the process loop and measurement takes place at the installation point, so the biogas sensor can be integrated into an existing control or monitoring system without engineering a separate sampling assembly.
The TCD3000 series is a more cost-efficient alternative to a gas chromatograph (GC) for continuous monitoring tasks. Unlike gas chromatography, where analysis runs periodically, the TCD3000 measures in real time and requires less equipment.
Measurement directly in the process stream

Materials of components in contact with the process gas

Part
Material
Screw-in housing
Stainless steel 316L
Sintered metal filter
Stainless steel 316L
Sensor material
Si, SixNy, compound, ceramics
Sealing
FKM, optionally FFKM or PTFE

When the TCD3000 is the right fit for biogas analysis

“It is important to separate two tasks here: multi-component gas composition analysis and continuous monitoring of a single component. If you need to measure CH₄, CO₂, O₂ and H₂S simultaneously, a multi-component analyzer does the job better. If you need continuous monitoring of one component in a defined gas matrix, the TCD3000 can be the technically simpler choice.”
Talk to expert
Tom Burkard
Archigas engineer
Tom Burkard

Where to use the TCD3000 in the biogas process

A biogas sensor does not have to be a multi-component instrument. Within a biogas plant it can perform one specific measuring function and pass the result to the process control system. The TCD3000 can be used at individual points along the process chain that require continuous CH₄, CO₂ or H₂ measurement – provided the gas mixture composition matches the capabilities of TCD.
Methane Slip monitoring
Measuring residual CH₄ in CO₂-rich off-gas keeps track of methane losses and shows how efficiently the upgrading process runs.
Methane quality control
CH₄ measurement for continuous verification of grid injection requirements.
Raw biogas at the digester outlet
Continuous CH₄ measurement in CO₂-rich biogas is possible once the actual gas matrix has been verified. High humidity and trace H₂S concentrations also matter at this point.
Biological methanation processes
H₂ measurement to monitor residual hydrogen and reaction progress, CH₄ to monitor methane formation and CO₂ to monitor residual CO₂ and conversion rate. H₂ in CH₄/CO₂-containing mixtures, CH₄ in CO₂ and CO₂ in CH₄ can all be measured.
Power-to-Gas systems
The analyzer can be used at the relevant point of the process chain for continuous monitoring of H₂ content in the gas stream.
Gas blending
The TCD3000 can monitor H₂ in methane-rich biogas.
CHP unit inlet
Monitoring the H₂ concentration in hydrogen-containing biogas to assess fuel composition and prevent operating modes with elevated knock risk.

Certifications & Compliance

Archigas products meet applicable international requirements for quality, safety and operation in hazardous areas.
ATEX Zone 1 certification icon
ATEX Zone 1 (II 2 G Ex db IIC T4/T3 Gb, -40°C to +90°C/+125°C)
Certification for use in potentially explosive atmospheres
IECEx certification icon
IECEx
International conformity certificate for explosive atmospheres
UL HazLoc certification icon
UL HazLoc
Certification for USA (hazardous locations)
CE marking icon
CE
Compliance with European Union requirements
ISO 9001:2015
ISO 9001:2015
Certified quality management system

Operation in biogas systems: Archigas TCD3000 vs a conventional analyzer

The difference between the two approaches comes less from the sensor itself than from the measurement architecture: an extractive system with gas conditioning versus inline installation directly in the process stream.
Parameter
Conventional CH₄/CO₂ analyzer
Archigas Biogas Analyzer
Gas conditioning
Required. A scrubber or filter is used to protect the sensing element
Not required under suitable conditions. The need for additional conditioning depends on humidity, condensate and other contaminants.
Installation complexity
High – sampling lines, filters and dryers have to be installed, which multiplies the number of mechanical and electrical connections
Low – the instrument is mounted straight into the process line
Measuring point
Determined by the layout of the sampling and conditioning system
At the instrument installation point itself
Measurement mode
Periodic (GC) or continuous with a delay (extractive systems)
Continuous, real time, directly in the stream
Sample transport delay
The sample travels to the analyzer through an external sampling line. The delay depends on line length and the parameters of the conditioning system
None. The gas is not transported to a remote analyzer – measurement happens in the stream
H₂S in the gas mixture
For many types of biogas sensors H₂S acts as a poison – it has to be removed upstream of the instrument
Resistance to trace H₂S concentrations confirmed in field use
Replacement frequency
Higher when exposed to aggressive media
Standard, including operation in demanding industrial conditions
System maintenance
Required for sampling and conditioning components (filters, scrubbers, dryers, pumps, regulators)
Minimal scheduled maintenance thanks to fewer components. Recommended recalibration – every 6 months.
Cost of ownership
Higher (more equipment)
Lower thanks to the inline architecture
Important!
Whether the TCD3000 can operate in the presence of hydrogen sulphide depends on the conditions of the specific process. Request an assessment for your gas composition.
Technical application assessment

FAQ

H₂S can damage the sensing elements of certain gas sensor types and degrade their performance. In catalytic sensors, one of the main damage mechanisms is poisoning of the catalytic surface by sulphur compounds. TCD technology does not rely on a catalytic reaction, so this mechanism does not apply to it. The TCD3000 SiA and TCD3000 Si are confirmed resistant specifically to trace concentrations of H₂S. Operation at higher H₂S content has to be assessed separately for the particular application.
No. Whether a scrubber is needed depends on the biogas composition and the H₂S concentration. If H₂S is present at trace level, no special H₂S version of the TCD3000 SiA or TCD3000 Si is required. At higher H₂S concentrations, operation without additional gas conditioning has to be assessed against the conditions of the specific process (gas mixture composition, measuring range, pressure, temperature and other parameters).
Yes. H₂S changes the thermal conductivity of the gas mixture and can therefore influence the instrument signal. If the gas composition and process conditions are known, this influence can be determined and compensated through individual cross-sensitivity correction.
The Biogas analyzer TCD3000 SiA and TCD3000 Si support Modbus RTU over the RS485 interface, plus a 4–20 mA analog output. RS485 runs at 38400 baud with 8 data bits.
The standard recommended recalibration interval for the TCD3000 is 6 months. In continuous operation on raw biogas, the actual interval may depend on the gas mixture composition and process conditions, including H₂S content and other impurities.
The instrument ships factory-calibrated for the parameters of your specific process, application conditions and gas composition. If known additional components are present in the biogas, individual correction of their influence on the measurement result can also be applied during factory setup – a technical option that is assessed project by project.
Yes. The TCD3000 SiA and TCD3000 Si connect to industrial control systems via 4–20 mA and RS485. The specific integration scheme depends on the architecture of the customer’s PLC, SCADA or other equipment.
That depends on the actual gas composition at the measuring point. TCD suits binary and quasi-binary mixtures, whereas raw biogas may contain CH₄, CO₂, H₂S, H₂, O₂ and water vapour at the same time. The gas matrix therefore has to be verified for a point immediately downstream of the digester.

Same technology, other gases

Electrolyzer hazardous-area monitoring
Monitoring H₂ crossover on the oxygen side of the membrane and atmospheric leaks inside the electrolyzer enclosure at working pressures up to 200 bar. The zone is classified as explosive and requires ATEX Zone 1 certification.
Fuel cell test benches and FCEV manufacturing
Leak detection on the anode side, in the reformer, and at high-pressure connectors. In enclosed test chambers, hydrogen accumulates at the top – the sensor is mounted at ceiling level.
Hydrogen refueling stations (HRS)
Continuous leak monitoring in compressors, dispensers, and storage vessels operating at 350/700 bar. Mandatory compliance with ISO 19880-1 and ISO 19880-8.
H₂ storage and transport
Monitoring of gasholders, tube trailers, and liquid hydrogen tankers. Coverage includes perimeter areas and the interstitial space of tanks.
Hydrogen blending into natural gas networks
Detection of H₂ leaks from H₂/CH₄ blends in gas distribution networks where hydrogen is admixed with natural gas.
R&D / catalyst testing/semiconductor
Leak monitoring of forming gas (5% H₂ / 95% N₂) in reactor lines and test chambers. Used in research laboratories and semiconductor manufacturing.

Need an analyzer for a specific point in your biogas process?

Archigas can assess whether the TCD3000 SiA or TCD3000 Si fits the actual parameters of your process gas and installation conditions. An initial assessment requires the gas composition, the component to be measured, the concentration range, pressure, temperature, flow rate and area classification.
To have a solution selected for you, send us the technical parameters of the installation and a description of the required measuring point.