Aerial view of a biogas plant with digesters
Aerial view of a wastewater treatment plant with round clarifiers
Gas Dome 300 – floating measuring hood by Fresenius Instruments on a clarifier
Aerial view of a recycling station with trucks and containers
Service van of Fresenius Instruments in front of the company building
World map with partner location and contact person
Aerial view of Wiesbaden with the Market Church

Gas analyzer manufacturer – process measurement technology

Solutions for

Biogas plants

Continuous measurement of CH₄, CO₂, O₂, H₂S and H₂ in biogas – from digester to grid injection.

Biogas measurement

What we do

Online and continuous process gas analyzers – extractive measurement

A gas analyzer measures the concentration of one or more gases – in process gas, in ambient air or in a safety atmosphere, continuously and in real time.

In Herten, Germany, we develop and build extractive online and inline gas analyzers – plus sample gas conditioning and the evaluation of your measurement data. The BioBasic shows how it all works together.

01 Sample

The sample gas comes straight from the process

A powerful pump draws the gas through probe and line to the device – even over long distances. This way the BioBasic measures up to five sampling points, from digester to grid injection.

02 Condition

Clean, dry gas for a stable reading

Before the gas reaches the measuring cell it is filtered and freed of condensate. For very humid process gases our sample gas coolers dry the gas beforehand.

03 Measure

Five gases, measured continuously

Infrared (NDIR) measures methane and CO₂; electrochemical sensors capture oxygen, hydrogen sulphide and hydrogen. The display shows all values at a glance.

  • CH₄
  • CO₂
  • O₂
  • H₂S
  • H₂

04 Use the data

Readings that control your process

The readings go to your plant control system – and, with the Cloud Connect Kit, to your smartphone too, with remote diagnostics and notifications.

Discover the BioBasic All gas analyzers

Industries

Process measurement for your industry

Biogas plant, chemical works or laboratory: our gas analyzers measure wherever processes have to run safely and efficiently.

All applications

Measuring principles

Six ways to measure a gas

Which measuring principle fits depends on your gas, the measuring range and the rest of the sample gas. Our process measurement technology combines the principles – even in one device.

Which gas do you want to measure?

Six measuring principles

Infrared (NDIR)

Infrared light passes through the heated measuring cell. Every IR-active gas absorbs at its own wavelength – so the device measures gases selectively and with long-term stability.

Typical for CH₄, CO₂, N₂O, solvents, refrigerants

GA 320 GA 220 GA 210 GA 150 Smart Control 300 GAP 100 BioBasic

How NDIR works

Infrared hot and wet

The measuring cell is heated to 85 °C, the sample gas arrives uncooled through a heated hose. Water-soluble gases stay in the gas instead of being lost with the condensate.

Typical for formaldehyde in the exhaust of gas engines

GA 315 Hot Gas

Paramagnetic

Oxygen is attracted by a magnetic field – unlike almost all other gases. This makes the measurement selective and needs no consumable sensor. The sample gas has to be dried for it.

Typical for O₂, for example during inerting

GA 210 O₂ paramagnetic

Zirconia

A heated ceramic conducts oxygen ions, the resulting voltage shows the O₂ content. Fast and compact – for gas without silicones, fluorinated hydrocarbons, sulphur oxides and hydrogen.

Typical for O₂ up to 100 vol.%

Smart O₂ Smart O₂ Portable GA 210 GA 220

Electrochemical

The gas reacts at an electrode, the current is proportional to the concentration. Compact and accurate for individual gases – also as a complement to NDIR in the same device.

Typical for O₂, H₂S, H₂

GA 210 GA 220 BioBasic GAP 100

Thermal conductivity

A heated element releases heat into the gas – hydrogen conducts it much better than air. As a module in the GA 210 or GA 220, it measures H₂ even at high concentrations.

Typical for H₂

GA 210 GA 220

Measuring hydrogen

In numbers

Our measurement technology is part of industrial plants worldwide

  • 6,000+

    devices in operation

    Gas analyzers from Herten measure around the clock – in biogas plants, wastewater treatment and industrial processes.

  • 460+

    plants worldwide

    From biogas plants to chemical works, our process measurement technology is an integral part of the plant.

  • 124+

    markets

    With partners and our own service team we support customers all over the world.

  • 30+

    years of gas analysis

    We have been developing process measurement technology since 1992 – today with cloud connectivity and AI.

Chemical park at dusk, reflected in a canal

From the measuring task and the concept to the finished measuring point – we support your project.

Let's talk

Products

Gas analyzers and sample gas coolers from Herten

From the biogas analyzer to the multi-gas device for six components – plus sample gas conditioning from our own production.

All gas analyzers

Advantages

The Fresenius advantage

  • Reliable in continuous operation
  • Continuous online measurement
  • Fully automatic operation
  • Automatic zero-point correction
  • Powerful pumps for long sample lines
  • Reliable service – also at your site
  • Direct line to support
  • Low service costs
  • Modern technology from an innovative manufacturer
  • Made in Germany

Applications

From digester to exhaust air: our process measurement in action

All solutions
  1. Biogas plant with digester and gas pipes 01 Biogas & biomethane Measuring points from digester to grid injection
  2. Biogas calculator on a tablet 02 Biogas calculator What better gas analysis brings your plant
  3. Gas Dome 300 on an aeration tank 03 Wastewater treatment Measuring nitrous oxide, methane and digester gas
  4. Recycling plant with bales 04 Recycling Refrigerants, blowing agents and inerting
  5. GA 320 in a control cabinet 05 Sample gas analysis Six measuring principles, one contact
  6. RCI 700 sample gas cooler 06 Sample gas conditioning Cooling and drying sample gas
Tory in front of the headquarters in Herten
Tory discusses measurement data on a tablet with a customer in the plant room
Tory shows an engineer a flow simulation in a measuring cell

About us

Made in Germany · Herten

Over 30 years of gas analysis – a digital pioneer today

We develop, build and service our process measurement technology in Herten, Germany – with our own lab, our own software and our AI advisor Tory.

  1. 1992Fresenius Umwelttechnik GmbH is founded
  2. 2010The BioBasic arrives
  3. 2018ISO 9001 and Fresenius Instruments
  4. 2025Tory and the Cloud Connect Kit

Our roots go back to 1848 and the laboratory of Carl Remigius Fresenius in Wiesbaden.

We make processes measurable – precisely, reliably and so easy to operate that you can focus on your process instead of the measuring technology.

  • Measure preciselyreliable values in continuous operation
  • Control processessafer and more efficient with your readings
  • Cut emissionsmake methane and nitrous oxide visible

Measuring technology that thinks ahead: it evaluates measurement data in real time and helps you make the right decisions without deep expertise – all the way to automated operation. We are evolving from an instrument maker into a high-tech company with data at its core.

  1. Measure
  2. Connect
  3. Understand
  4. Act
  • AI in developmentiterate faster, test more
  • Toryreal-time dialogue in sales and support
  • Measurement datawith Cloud Connect Kit or local

About us Our team

News

Trade fairs, projects and news from gas measurement

All articles

Next trade fair

231 days

ACHEMA 2027

14–18 June 2027 Frankfurt am Main, Germany

Book a meeting at the fair All fairs and events

FAQ

Frequently asked questions about gas analyzers

What is a gas analyzer?

A gas analyzer measures the concentration of one or more gases – in process gas, ambient air or a safety atmosphere. Our devices work online and continuously: they draw the sample gas from the process, condition it and measure it around the clock.

What is the difference between a gas analyzer and a gas detector?

A gas detector raises an alarm when a limit is exceeded – it protects people. A gas analyzer measures the exact concentration, often of several gases at once, and passes the values to your control system so you can control and optimise your process. For threshold monitoring we also offer the Smart Control 300.

Which measuring principles do your gas analyzers use?

Depending on gas and measuring range: infrared (NDIR), paramagnetic and zirconia oxygen measurement, electrochemical sensors and thermal conductivity for hydrogen. We often combine several principles in one device.

How do you measure methane in biogas?

An NDIR sensor measures methane and CO₂; electrochemical sensors measure oxygen, hydrogen sulphide and hydrogen. The BioBasic measures these gases continuously at up to five sampling points – from the digester to grid injection.

Extractive or in-situ gas analysis – which suits my process?

In extractive measurement the sample gas is withdrawn, conditioned and measured in the analyzer – this protects the device and allows several gases and sampling points. In-situ devices measure directly in the process, such as the TINA for toxic and explosive gas mixtures. We work out the right solution with you based on gas, temperature and humidity.

How often does a gas analyzer need calibration?

That depends on the device, measuring range and application. Many plants need one maintenance and calibration per year; the automatic zero-point correction keeps the measurement stable in between. Our service team calibrates in Herten or at your site.

Why does a gas analyzer need a sample gas cooler?

Moist sample gas can condense in lines and the measuring cell and falsify the measurement. The sample gas cooler dries the gas before the analyzer. For water-soluble gases such as formaldehyde we measure hot and wet instead, so the component is not lost in the condensate.

Do you service gas analyzers from other manufacturers?

Yes. We maintain, calibrate and repair devices from other manufacturers too – in our workshop in Herten or at your site, and internationally with our service partners.

Who manufactures gas analyzers in Germany?

Fresenius Instruments has been developing and building gas analyzers and sample gas coolers in Herten, Germany, since 1992. Around the devices we offer advice, commissioning, service and training from a single source.

Advice

Tory – your gas analysis advisor

Which gas, which measuring range, which plant? Tory answers your technical questions right away, suggests suitable devices and, if you like, takes you straight to a quote or a meeting with our team.

  • Answers to technical questions – around the clock
  • Suitable devices for your measuring task
  • Direct path to a quote or meeting

Do you have a measuring task?

Tell us about the gas, process and measuring range – we design the right process measurement technology with you.

Request a quote Book a call

Measuring What Matters

GAS ANALYZERS · MADE IN GERMANY · SINCE 1848