Gas Analyzers

What Is a Gas Analyzer?

Gas AnalyzerReal-time gas analysis enhances efficiency, safety, throughput, product quality, and ensures environmental compliance. Gas analysis utilizes various technologies such as tunable diode laser spectroscopy, zirconia oxygen analysis, infrared gas analysis, stack gas analysis, dust monitoring, process gas chromatography, continuous emissions monitoring systems (CEMS), hydrogen purity analysis, and gas density systems. Selecting the correct technology is critical to measurement accuracy, reliability, and durability.

Yokogawa's years of application expertise enable our customers to save time, money, and resources by collaboratively selecting the optimal gas analyzer solution.

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What Is a Gas Density/Hydrogen Purity Analyzer?

GD402/GD40 Gas Density Meter

  • Measures gas density with high sensitivity and quick response. Also capable of displaying specific gravity and molecular weight derived from the density data.
  • Can be used in hazardous areas with explosive atmospheres (FM, CSA, TIIS)
  • Hydrogen purity and replacement meter for power generators

What Is a Zirconia Oxygen Analyzer?

ZR402/ZR202 Zirconia Oxygen Analyzers

  • Measurement with probe directly inserted into furnace or boiler
  • Integrated and separate types available
  • Also can be used as a high temperature humidity analyzer
  • Fully field-repairable probe
  • HART communication
  • Explosionproof (FM, CSA, ATEX) (ZR22S, ZR202S)


Application Note

The U.S. refineries represent approximately 23 percent of the world's petroleum production, and the United States has the largest refining capacity in the world. Petroleum refining is an industry, which is undergoing intense amounts of scrutiny in the United States from regulatory agencies and environmental groups.


Yokogawa’s Tunable Diode Laser Spectroscopy (TDLS) is the ideal solution for both oxygen and carbon monoxide measurements in process furnaces that have aggressive and corrosive components.


VOC (Volatile Organic Compounds) are compounds that evaporate easily at room temperature. They generate photochemical oxidants and cause soil and water pollution.


Environmental pollution caused by volatile organic compounds (VOCs) has become a global environment issue, including issues on effects upon health. This paper introduces a system based on detection and sampling technologies and developed for measuring goes in the global environment. Small amounts of VOCs are measured with a gas chromatograph or photoionization detector (PID). VOCs in water are sampled using a sparging method. A small quantity of VOC constituents of more than 20 different types can be measured with a gas chromatograph using a programmed temperature oven. The PID can detect a ppb level of VOCs that are ionized using a vacuum ultraviolet radiation lamp. We expect these devices will be useful for improving the global Environment.

Media Publication

Marcus Trygstad, Yokogawa Corporation of America, outlines the advantages of EUVF technology for total reduced sulfur measurement in flare gas.

Media Publication
Edition 1

The EPA rule, 40 CFR 63 Subparts CC and UUU, is forcing refineries to monitor flares. Fortunately, modern analyzer technology makes it possible to meet the requirements, generate the necessary reports, and stay in compliance.
Here’s how to select the right analyzer to meet these demands.

Media Publication
Edition 1 1

Vibrating element (VBE) type gas measurement devices measure refinery reformer stream compositions, power generator hydrogen purity, centripetal compressor gas inputs, process heater fuel gas quality, and others in multiple process control environments.

Media Publication
Up Your Fired Heater Safety with TDLS Technology
(Chemical Processing - eHandbook)
Edition 2022.05.03 1

Protect Plants from Process Perils, Up Your Fired Heater Safety with TDLS Technology - Chemical Processing - eHandbook April 2022


Are you trying to decide how to tackle that next challenging application? Join our Back to Basics webinar series as we review the fundamentals behind different measurement technologies. We will discuss recommended practices, application selection, and sizing, and how to avoid common pitfalls. Gain insight directly from our experts!

Please read the attached handout for more information. We no longer offer the Transistor style Cold junction. If using an older electronics (ZA8C/ZO21C/AV8G/AV8C) the unit will have to be replaced with a newer model and a K9470BG cold junction can b...
The password to access the maintenance and commissioning area is 77
AV8C Channel reset code
You can use code 58 to reset a single AV8C channel.  First scroll the display to the channel you would like to cycle, then enter code 58. 
Here is the link to download the AV8G Manual.
The part number you see on the channel card circuit board is not the part number for the channel card. It is the part number for the circuit board before any parts are installed.  There are 2 versions on the channel card.  If you look at ...
The AV550 automatically turns off the power to the channel card when it is removed. You have to either cycle power to the whole unit, or use the channel card power.  To get to the channel card power menu hit the Setup Key (wrench). See below:&n...
You can use the password JAVAJAVA to get past the password screen. Make sure you go to the password menu change the password setting. 
Yokogawa has been making Zirconia Oxygen Analyzers for over 30 years. The older O2 probes and analyzers used a transistor temperature sensor. The newer units use a PT1000 RTD. We discontinued the ZO21D probe and both the AV8G and ZA8C analyzers over ...
Meter Checks: Heater: 57-85Ω (typical is 62-67Ω) Typical failure is Open or shorted TC: if the probe is at room temperature -  less than 3Ω, in the stack and hot less than 100Ω (it is a type K Thermocouple) Typical failure is ope...
ZR22 Bolt Sizes
The ZR22 probes have the following bolt sizes  Cell Bolts (4 ea.) - 8mm  Housing bolts (4 ea.) - 10mm  Heater strut retaining nut (K9470BA) - Custom thread. You may need the nut removal tool to loosen this nut: You can purcase it se...
The wiring between the ZR402 Detector, the ZR22 Sensor, and the AC1 Autocal Panel is shown below. The Wiring between the ZR402G and the ZR22G must be installed in 2 separate conduits, one for the signal cable, and the other for the heate...
Factory Recommended Method Use only 99% Isopropyl alcohol. Alcohol that is less than 99% will take longer to dry. Sometimes much longer. Denatured Alcohol is not 99% and should not be used. Clean with 99%  isopropyl alcohol. Pour alcohol ...
Whenever you are installing a gas density system, it is important to match the detector (GD40) to the analyzer (GD402). This applies to completely new installations, as well as when a GD40 detector is being used with a different analyzer. To match th...
If your analyzer has been up and running properly but when you try to calibrate you receive an "alm 10" code, then clean the detector and try again.    See the below for cleaning instructions ...
HA400 Instruction Manual
See link

Get the most from what exists currently and take advantage of new methods. Appeared in the March 2021 issue of an publication.





TDLS8100 & TDLS8200 Features and Benefits Video


Yokogawa’s new TDLS8000 houses all of the industry’s leading features in one robust device. The platform design is for in situ measurements which negate the need for sample extraction and conditioning. The non-contacting sensor allows for a variety of process types including corrosive, abrasive and condensing. The first generation platform has been proven in many others for the measurements of O2, CO, CH4, NH3, H2O and many more NIR absorbing gases. This second generation platform has improved reliability and ease of installation and maintenance while still meeting or exceeding designed application demands.


Nick Crowe discusses whether to calibrate or validate your analyzers. He demystifies the differences between both options and uncovers the truth about performing either.


This time around, Nelson Isea discusses the many misconceptions around Gas Chromatographs. Technicians see this machine as Black Magic, too complex to understand and believe a Chemistry degree is necessary to service them. Tune in to find out more about this insightful chat.

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