In-Situ Gas Analyzer TDLS8000

Yokogawa’s new TDLS™8000 houses all of the industry’s leading features in one robust device. The platform design is for in situ measurements which negates 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.

The most trusted laser analyzer designed specifically to meet all of your requirements in one robust device that is easy to operate and maintain.




  • SIL2 TruePeak combined with smart laser Technology
  • Intuitive touchscreen HMI
  • HART and Modbus TCP communications standard
  • 8-stage auto-gain adapts to difficult applications
  • Fully field repairable with 50 days of data and spectra storage
  • Compact design for one-man installation without sacrificing ruggedness
  • Area classification Zone2/Div2 or Zone1/Div1

System Configuration

High Reliability

  • Reference Cell
    Internal reference cell in the laser module ensures peak locking during trace measurement.
  • Auto gain
    Auto-gain enables wide signal ranges against dynamic variation of transmission.

  • Validation
    Validation can be initiated manually, remotely, or automatically on a daily, weekly or monthly basis defined by the user.
  • SIL2 certified
    IEC61508 SIL designed & approved, SIL2 capability for single analyzer use, SIL3 capability for dual analyzer use.


The TruePeak we can measure the area of the absorbance peak. This eliminates effects from changing background gases, allowing for simple pressure and temperature compensation.

Intuitive touchscreen HMI

  • Touch screen 7.5 inch color LCD on HMI
    Makes it simple to operate
    Gives all the information including trend graph and eliminate PC to maintenance
    Can be remotely installed
    TDLS8000 TouchScreen
  • Mini Display
    Optical transmission at both the ends for easy Alignment
    TDLS8000 display

Standard Specifications

Measurement object O2, CO, CO or CH4, CO2, CO + CO2, H2O, NH3, NH3 + H2O, H2S, HCl concentration in combustion exhaust gas and process gas
Measurement system Tunable diode laser spectroscopy
Measured components and range Measured component Min. range Max. range
O2 0-1% 0-25%
CO(ppm) 0-200 ppm 0-10,000 ppm
CO+CH4 CO 0-200 ppm 0-10,000 ppm
CH4 0-5 %
NH3 0-30 ppm 0-50,000 ppm
H2O (ppm) in non HC 0-30 ppm 0-30,000 ppm
H2O (ppm) in HC 0-30 ppm 0-30,000 ppm
CO (%) 0-20 % 0-50 %
CO (%) + CO2 (%) 0-30 % 0-100 %
 NH3 + H2O NH3 0-30 ppm 0-5,000 ppm
H2O 0-5 % 0-50 %
H2S 0-5 % 0-100 %
CO2 (%) High Range 0-1 % 0-5 %
CO2 (%) Extend.Range 0-30 % 0-50 %
H2O (%) 0-10 % 0-100 %
HCl 0-50 ppm 0-5,000 ppm
Output path length Optical distance between the laser unit and the sensor control unit Standard; 0.5 to 6 m, Max; 30 m
Output signal 2 points, 4 to 20 mA DC
Output types; Gas concentration, Transmission, Process gas temperature, Process gas pressure
Output range; 3.0 to 21.6 mA DC
Digital communication HART, Ethernet
Contact outputs 2 points, contact rating 24 V DC, 1 A
Function: Activate during Warning / Calibration / Validation / Warm up / Maintenance conditions
Function: Activate during normal condition, not activate during fault condition or when the system power is off
Valve control output 2 points
Function; Activate calibration or validation solenoid valves for zero, span or validation gas
Output signal; 24 V DC, 500 mA Max. per terminal
Alarm Warning;
Gas concentration low/high, Transmission low, Process pressure low/high, Process temperature low/high, Validation required, Validation failure, Zero/Span calibration error, Non process alarm, External alarm
Laser module temperature low/high, Laser temperature low/high, Detector signal high, Peak center out of range, Reference peak height low, Absorption too high, Transmission lost, Reference transmission low, Reference peak height high, Laser unit failure, Laser module error, File access error, E2PROM access error.
Contact inputs
(Digital input)
2 points
External alarm/Calibration start/Validation start/Stream switch
Contact specification;
Zero voltage contact input
Input signal; Open signal;
100 kΩ or more, Close signal; 200 Ω or less
Input signal
(Analog input)
2 points, 4 to 24 mA DC
Input types; Process gas temperature, Process gas pressure
Self-diagnostics Laser Unit temperature, Sensor Control Unit temperature, Laser temperature, Detector signal level, Memory read/write function, Peak locking condition
Calibration Calibration method; Zero/Span calibration
Calibration mode; Manual, Auto, Local initiate (HMI)
Validation Validation method; Up to 2 points
Validation mode; Manual, Auto, Local initiate (HMI)
Power supply 24 V DC ±10%
Warm-up time 5 min.
Protection degree IP66, NEMA Type 4X
Hazardous area classifications Division 1, Zone 1; Explosion-proof/ Flame-proof type; FM, cFM, ATEX, IECEx (Pending)
Division 2, Zone 2; Non-Incendive/Type n; FM, cFM, ATEX, IECEx, KOSHA, NEPSI
Process gas condition Process gas temperature; Maximum 1500℃
Process gas pressure; Max. 1 MPa, Min. 90 kPa
Dust in process gas; 20 g/m3 or less
Installation condition Ambient operating temperature; -20 to 55℃
Storage temperature; -30 to 70℃
Humidity; 0 to 95%RH at 40℃ (Non-condensing)
Mounting flange type; ASME B 16.5, DIN, JIS
Gas connections; 1/4 NPT or Rc1/4
Purge gas;
   Recommended purge gasses
   O2 analyzer; N2 (99.99% or greater, application dependent)
 H2O ppm analyzer; N2 (99.99% or greater with < 20 ppm H2O for feed to the optional dryer package)
CO, CO or CH4, CO2, CO+CO2, NH3, NH3+H2O, H2S, HCl;
   N2 (99.99% or greater, application dependent) or Instrument air  CO, NH3 analyzer: N2 (99.99% or greater, application dependent) or Instrument air
Purge gas flow rates;
   5-20 L/min for optic
   5-30 L/min for process window
Purge gas connections;
   1/4NPT (-G1, -C2, -D2, -C2, -D1, -C1),
   Rc1/4 (-G2, -S2, -E2, -J2, -E1, -J1)


Measurement gas Repeatability Linearity
O2 ± 1% reading or ± 0.01% O2, whichever is greater ± 1% F.S.
CO (ppm) ± 2% reading or ± 1 ppm CO, whichever is greater ± 1% F.S.
CO + CH4 CO ± 1% reading or ± 1 ppm CO, whichever is greater ± 2% F.S.
CH4 ± 4% reading or ± 0.02% CH4, whichever is greater ± 4% F.S.
NH3 ± 2% reading or ± 1 ppm NH3, whichever is greater ± 2% F.S.
H2O (ppm) in non
± 2% reading or ± 0.1 ppm H2O, whichever is greater ± 1% F.S.
H2O (ppm) in HC ± 2% reading or ± 0.1 ppm H2O, whichever is greater ± 1% F.S.
CO (%) ± 1% reading or ± 0.01% CO, whichever is greater ± 1% F.S.
CO (%) + CO2 (%) CO ± 1% reading or ± 0.1% CO, whichever is greater ± 1% F.S.
CO2 ± 1% reading or ± 0.1% CO2, whichever is greater ± 1% F.S.
NH3 + H2O NH3 ± 2% reading or ± 1 ppm NH3, whichever is greater ± 2% F.S.
H2O ± 4% reading or ± 0.05% H2O, whichever is greater ± 2% F.S.
H2S ± 1% reading or ± 0.005% H2S, whichever is greater ± 1% F.S.
CO2 (%) High Range ± 1% reading or ± 0.005% CO2, whichever is greater ± 1% F.S.
CO2 (%) Extend. Range ± 1% reading or ± 0.02% CO2, whichever is greater ± 1% F.S.
H2O (%) ± 1% reading or ± 0.004% H2O, whichever is greater ± 1% F.S.
HCL ± 1% reading or ± 2.5 ppm H2O, whichever is greater ± 2% F.S.

YH8000 HMI Unit

The YH8000 is a HMI designed specifically for the Tunable Diode Laser Gas Analyzer, the TDLS8000.

  • Touchscreen 7.5 inch color LCD on HMI
  • Makes it simple to operate
  • Can be remotely installed
  • Up to 4 units connection available


Display Touchscreen 7.5 inch TFT color LCD panel, 640 x 480 (VGA)
Communication Ethernet; RJ-45 connector, Communication speed; 100 Mbps
Protection degree
of enclosure
IP65, NEMA Type 4X
Weight 4 kg
Mounting Analyzer mount (Front, left-side, right-side) with tilt function, Pipe mount or Panel mount
Cable Entries 1/2NPT or M20 x 2
Ambient operating temperature; -20 to 55℃
Storage temperature: -30 to 70℃
Humidity: 10 to 90%RH at 40℃ (Noncondensing)
Power Supply 24 V DC ±10%
Hazardous area
Division 2, Zone2: Non-Incendive/Type n; FM, cFM, ATEX, IECEx, KOSHA, NEPSI

The simple and robust TDLS8000 assures the reliable and less maintenance operation of the analysis.

Fired Heater Combustion Safety and Lifecycle Management

Yokogawa TDSL8000 and CO + CH4 measurements provide reliable information to achieve:

Fired Heater Combustion Safety and Lifecycle Management

  • Combustion efficiency improvement
  • Safety improvement
  • Longer lifetime of the coils and coil hangers
  • Higher throughout of the process heating


Limited O2 Concentration

O2 Measurement for Safety and Process Monitoring & Control Yokogawa TDLS8000 02 analyzer achieves:

Limited O2 Concentration

  • No sampling system operation
  • Fast response analysis
  • No interference analysis
  • Less maintenance operation



Fired heaters are used for various processes in oil refining and petrochemical plants.


In maintaining and managing industrial plants, monitoring waste water pH/ORP is both a legal obligation and an unavoidable necessity for protecting the environment. Monitoring without an attentive eye can lead to severe consequences.


Considering safety and environmental issues such as combustion efficiency and decreasing NOX and CO in exhaust gas, it has become important to control O2 concentration in garbage incineration processes.


H2S management of exhaust gas in black liquor recovery boilers is required to meet an environmental regulations.


Industrial Combustion sources such as thermal cracking furnaces and, process heaters play a critical role in the process industry.


The ammonia (NH3) gas is injected to remove the NOx and thus reduce the NOx concentration in the stack flue gas. With conventional NH3 analyzers that perform measurements indirectly, NH3 concentrations are obtained through a sampling system. Therefore, there are problems with the maintenance and running costs of the sampling system, and time delays in measurement. The TDLS200 Laser Analyzer is the solution to all these problems.


O2 measurement in hydrocarbon vapor is used for safety monitoring in vacuum distillation columns in petroleum refining. With conventional paramagnetic oxygen analyzers, O2 concentrations are obtained through an extractive sampling system, which conditions the sample prior to being analyzed.


Storage tanks are used in a variety of industries ranging from holding crude oil to holding feedstock for vinyl chloride monomer (VCM).


If water is present after the dry chlorine tower in brine electrolysis plants, the downstream compressor is corroded or the product quality is deteriorated. The moisture level is measured before and after the compressor to prevent the corrosion of the compressor and the deterioration of quality.


O2 measurement is used to safely recover flue gas containing a high concentration of CO from a converter furnace. With conventional paramagnetic oxygen analyzers, O2 concentrations are obtained through a sampling system to recovery flue gas. Therefore, there are problems with the maintenance and running costs of the sampling system, and time delays in measurement.


Spectrometric technology can assess many critical characteristics about products, but it has limits. It can be challenging to determine when the line has been crossed


With fired heaters, users hope to get greater efficiency and reduced emissions but often are disappointed. Given the number of fired heaters operating every day and their importance in the process industries, any improvements realized across the board will have huge impacts. More units can reach their potential with some simple changes in work practices and technology upgrades.


SABIC is a global manufacturer of polymer resins, film and sheet products, special additives, and chemical intermediates. With operations in more than 50 countries, the company has an enormous variety of processes and plant designs to make its range of products. With so many plants, processes and products, there are frequent opportunities to make improvements with hardware and instrumentation.

A case in point is a reaction process in which oxygen gas is sparged into the reactor, and there is a resulting outlet gas stream. Proper and timely measurement of the oxygen content in this outlet stream is of key importance for reaction control and safety. Reaction progress, control of raw materials input, and reaction sequencing are all affected and dependent on the value of the oxygen concentration reading. The reactor contents and outlet stream can also be in the flammable range depending on conditions, so safety and process considerations call for continuous monitoring of the vent line contents.

A Two-Fold Measuring Function

The safety considerations of monitoring oxygen content in the vent line are very important. As long as the oxygen level remains below a limit, the mixture can be kept below the flammable range and will not undergo combustion. If the process allows the concentration to exceed this limit, it shuts off the oxygen flow to the sparging headers. But this safety consideration is only one of the reasons the measurement is important.

Secondly, the amount of oxygen bubbling through the liquid is an indicator of what is happening in the reaction. Oxygen consumption depends on reaction chemistry and it is a direct indication of the status of the process. Accurate reading of overhead oxygen content is especially important for control of reactant addition and temperature control.

The Challenges of Consistent Measurement

Technologies to measure oxygen in a gas stream are not new, and there are countless applications in chemical manufacturing and other industries where oxygen levels need to be monitored. Combustion processes of any size invariably use some type of oxygen sensor in the flue gas stream to maintain efficiency.

SABIC’s situation proved to be more challenging than most typical applications due to a mix of specific conditions. For many years operators struggled while working with paramagnetic and electrochemical cell sensors due to degradation of the cells, moisture and debris from the process. These sensors are both very common and used in a wide variety of oxygen measuring applications, but they have some key limitations that became apparent when reviewing this process.

Paramagnetic analyzers are sensitive to vibrations and cross-contamination from other gases. Although the application for these reactors does not call for measuring trace amounts of oxygen, there are also sensitivity issues at very low concentrations. Electrochemical cells should be replaced routinely and have sensitivity to different pressures, temperatures and cross-contamination.

Our sampling systems experienced high failure rates with electrochemical components including sampling lines being plugged from the process, filter element clogging, and failing pumps. Moreover, since an individual test during production took more than two minutes, a possibility existed that a climbing oxygen level may not be identified soon enough.

Paramagnetic and electrochemical cell oxygen analyzers have a three-month verification frequency, and the manufacturers recommended maintaining this regimen precisely. Although the testing does not take long, production was delayed in some situations while performing the verification. Delays and Emergency work due to the failures of these types of analyzers resulted in a significant amount of lost production. Due to these and other issues, a more robust oxygen analyzer technology was required.

Tuning in to Laser Technologies

One technology used commonly in combustion processes is tunable diode laser (TDL) spectroscopy, capable of detecting and measuring a variety of gasses, including oxygen, within many contexts. Theoretically, it has the capability to measure oxygen when mixed with toluene, but there was some concern about it being practical for this specific application.

A TDL analyzer sends a beam with a controlled wavelength range through the gas being analyzed to determine which products are present based on which specific wavelengths of light are absorbed. The problem in this case related to the duct size, because the transmitter and receiver should be a minimum distance apart to ensure adequate absorption.

The duct diameter here was less than half the normally recommended distance, so there was some concern as to whether it would deliver its full degree of accuracy, or even work at all. SABIC’s engineers felt the potential benefits to be gained were more than enough to justify installing one analyzer as a test. The performance would be easy to evaluate since the existing sensors were still fully operational and working in parallel.

After two weeks of operation, it was clear the Yokogawa TDL analyzers were performing very well (Figure 1). It was true that they were not delivering the full degree of precision they were capable of due to the short scanning distance, but the precision was high enough to satisfy the needs of the process.

Figure 1. While the duct size for this application was smaller than is usually recommended for TDL analyzers, the tunable diode lasers reliably provided readings with a high enough degree of accuracy for the application, while eliminating the maintenance problems associated with the earlier sensing technologies.

Once installed, the new analyzers proved very reliable and required far less validation and maintenance than the earlier technologies. One issue proved to be debris carried into the duct from the process blocking the light transmission path between the transmitter and receiver. Adjustments to a nitrogen purging system and better control of the process itself minimized this effect, leading to virtually trouble-free operation.

Facilitating the Safety Function

All of these TDL analyzers have been installed for over two years now, with no failures due to the TDLA’s to date. Some units were outfitted with the Yokogawa TDLS200 analyzer, while others were outfitted with the Yokogawa TDLS8000 models. There are other manufacturers of this technology but we chose Yokogawa for this application.

There have been occasional visibility blockage incidents, but these are rare after adjustments to the purge system. Overall, these TDL analyzers have supported higher levels of production, and added another layer of protection to the unit.


Yokogawa Europe expert Arthur Groenbos discusses tunable diode laser gas analysis for combustion management in fired heaters. While fired heaters are used throughout refining and petrochemical processes as the source of process heat, they carry inherent risks and costs that make operating without current technologies problematic.

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