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Gas analyzer and gas sensors for oxygen, CO and moisture monitoring

Gas Analyzers and Gas Sensors

Rethinking gas analytics with in situ and extractive gas analyzer technology for industrial installations

Gas Analyzer - Frequently Asked Questions (FAQ)

What is a Tunable Diode Laser analyzer (TDL analyzer)? Tunable diode laser analyzers are gas analyzers that are used for measuring the concentrati...

What is a Tunable Diode Laser analyzer (TDL analyzer)?

Tunable diode laser analyzers are gas analyzers that are used for measuring the concentration of specific species within a gas mixture using laser absorption spectrometry. Simply put, a laser beam, tuned to identify a particular gas species, passes through the gas to a detector. The presence of this gas in the stream causes light absorption and reduced signal intensity. The light collected at the detector is detected by a photodiode and analyzed to quantify the gas concentration.

TDL gas analyzers are rapidly replacing other technologies in process plants because they offer increased productivity, capacity upgrades and higher safety.

How can I reduce maintenance and installation costs with a TDL analyzer?

Installing a TDL in situ gas analyzer allows you to eliminate the sample conditioning system that is required with standard extractive techniques. In addition, due to the one-flange, folded path concept showcased by METTLER TOLEDO's GPro 500 Gas Analyzer, you can further reduce the installation and maintenance costs related to typical TDL process gas analyzer alignment.

What gas species can be measured with a TDL analyzer?

METTLER TOLEDO GPro 500 Gas Analyzers offer measurement of carbon monoxide (CO%), carbon dioxide (CO2%), hydrogen chloride (HCl), hydrogen sulfide (H2S), gaseous oxygen (O2) or moisture. We are continuously expanding our offering of parameters to support industry needs.  These can be paired with a wide range of process adaptions to provide the process gas analyzer to meet your requirements.  For example, an oxygen gas analyzer can be paired with a filter probe to allow you to install an oxygen analyzer in a gas stream that has heavy particulate. That same oxygen gas analyzer can be paired with a wafer adaption to create an in line gas analyzer for oxygen in a small line size (down to DN50).

What are some suitable applications for a TDL analyzer?

TDL gas analyzers are used in a wide range of applications across a variety of industries. Installations are common in chemical industries, petrochemical refining, pharmaceutical manufacturing, and food and beverage production.

In industries such as chlor-alkali, TDL gas analyzers can replace traditional measurement systems for moisture monitoring to prevent compression system corrosion.

A GPro 500 with a filter probe adaption is optimal for process gas analyzers in combustion applications where high dust loads could typically obstruct measurement. This setup is particularly appropriate for fired heaters and boilers.

In inerting and blanketing applications, the use of a non-purge probe on a gas analyzer provides increased safety and reduces running costs.

For in situ gas analyzer measurement in DN50 or 2" pipes when you have high or low velocities or where you wish to avoid flow restrictions, the GPro 500 Wafer Cell adaption provides stable measurement.

What is an amperometric oxygen gas sensor?

Amperometric, or polarographic oxygen sensors, are sensors for measuring gaseous oxygen using an oxygen permeable membrane and an electrochemical anode/cathode assembly. These process gas sensors are good for gas monitoring in applications such as nitrogen blanketing and off-gas monitoring.

Amperometric oxygen gas sensors provide fast measurements and are quick and easy to replace, calibrate and maintain.

How often do I need to service an amperometric gas sensor?

The inner body of an amperometric oxygen gas sensor requires occasional replacement. More frequently, the electrolyte in the sensor's membrane body will need replenished and the membrane body itself, replaced. Replacement/refilling times vary based on individual application conditions and knowing when to conduct these tasks is often down to the experience of operators.

METTLER TOLEDO's amperometric gas sensors with Intelligent Sensor Management (ISM) technology offer diagnostic tools that show, in days remaining, when inner body and membrane body replacement or electrolyte refilling should be performed. These tools, such as the Dynamic Lifetime Indicator, help to ensure that you avoid any unplanned downtime in your monitoring and control processes.

How often do I need to calibrate an amperometric gas sensor?

Calibration intervals are difficult to calculate, but ISM technology will give you an estimate based on the conditions of the process the gas sensor is operating in. The Adaptive Calibration Timer (ACT) provides an accurate calculation for when you should plan to calibrate your gas sensor, meaning less unplanned downtime or process interruptions.

Tunable Diode Laser (TDL) Gas Analyzers

Tunable Diode Laser Gas Analyzers

Designed for in situ and extractive chemical processes, these TDL gas analyzers are easy to install and require almost no maintenance.
No alignment needed with one-flange probe concept
Drift-free measurement requires no calibration
Fast response time with in situ installation
Options for extractive and cross-pipe installation
Tunable Diode Laser (TDL) Gas Analyzers

Designed for in situ and extractive chemical processes, these TDL gas analyzers are easy to install and require almost no maintenance.


Technical and Application Information for Gas Measurement

Gas Analysis Brochure
Tunable Diode Laser Spectrometry – Theory and Background eBook
White Paper: HCL Monitoring in Stacks and Scrubbers
Process Analytics Product Catalog


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