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The Teledyne ML®675 dilution-extractive system can be used in 40CFR75, 40CFR60, 40CFR63, and process control applications. In this system, sample is prepared for analysis by diluting stack gas with clean, dry instrument air at the probe location. Since no moisture is removed with dilution, measurements for SO2, NOx, CO, THC and CO2 are made on a wet basis.


675 Rear View.png


The ML®675 or 675 ®Open Architecture (OA) is a pre-engineered Continuous Emissions Monitoring System (CEMS) designed for use in EPA 40 CFR Part 60 and Part 75 compliance applications and for process control.  This dilution based system can be configured to accurately measure SO2, NOx, CO, CO2, and /or O2 on a wet basis.

Both configurations of the ML®675 CEMS consist of a heated probe, heated sample umbilical, single bay cabinet, analyzers, control equipment, and a dilution air cleanup package. The Open Architecture version has the dilution air cleanup package mounted on a wall instead of the cabinet.

Using dilution extractive principles, pressurized dilution-air is used as the motive force to provide suction that mixes a small amount of stack gas into the same dilution air stream.  This creates a diluted sample which returns under positive pressure to the analyzers for analysis.  A precision mass flow meter is used to determine an accurate, real time dilution ratio.  Since no moisture is actually removed from the original sample, measurements are made on a wet basis.

A programmable logic controller (PLC) performs all automatic sequencing of the sample cycle, daily calibration cycle, and back purge cycle.  During calibration mode, zero and span gases are injected into the probe head to comply with EPA calibration requirements.  Back purge air is delivered to the probe on a periodic basis to clean the heated probe filter, providing months of continued operation without maintenance.

In addition, the PLC has the ability to log fuel flows and provide the required analog outputs in units of diluent corrected ppm concentration (ppmc), lb/mmBtu, and lb/hour. Standard relay outputs that signal system status and fault information are also generated from the PLC.  A RegPerfect® Data Acquisition System (DAS) may be attached to the PLC via Ethernet to provide long term data collection, compliance report generation, remote control and diagnostic information.

The ML®675 is a self-contained system requiring single point attachment for power, instrument air, and calibration gases.  All utility distributions are routed through the ML®675 internally. No duplication of utilities is required on the stack.


  • EPA certifiable for all 40 CFR 60 and 40 CFR 75 applications.  
  • Well suited to generate reliable and accurate process control information.  Typical  applications include incinerators, industrial sources, and power boilers.
  • State of the art TML T-Series® analyzers are utilized for pollutant monitoring.  This allows a single source for system as well as analyzer support.
  • Automatic, local and  remote initiation of any system sequence is available. This includes the ability to zero and span a single analyzer both through the entire sampling train or directly at the analyzer to diagnose sampling system  anomalies.
  • Minimal maintenance is required. Weekly manual calibrations, quarterly probe checks, and quarterly filter changes are typically all the system requires to achieve uptime of 95% or greater.
  • Self-diagnosing alarm package.  The ML®675 will alarm the user for sample train heater failures, dilution air delivery problems, probe and analyzer faults.  This system is smart enough to protect itself during a fatal fault condition ensuring no moisture can contaminate any analyzer.



Standard 316L Stainless Steel or Hastelloy probe straw
EPA approved lengths

2 micron ceramic filter

Heated head maintained above 350°F (176.7 °C)

Components housed in a NEMA 4X enclosure



3/8" Teflon or 316 Stainless Steel sample tube

Tubes for calibration and backpurge standard

Frost free protection when required

Fire retardant jacket


Air Cleanup Package:

Provides dilution air at -100°F dew point

Free of CO2, NOx and SO2

Optional CO scrubber

Supports up to two dilution systems with additional hardware

Low instrument air alarm

Ballast tank provided for mixing and pressure stabilization

Precision mass flow meter for real time dilution ratio



Dual bay, 19" Rack Mount, NEMA 12 with fan ventilation

Other NEMA ratings are available.

Dimensions 80"H x 50"W x 40"D, Approx. 400lbs

Front door with window, rear door, removable side panels

Lifting lugs and/or castors can be provided



Open rack with optional desk.

Dimensions  80"H x 63"W x 30"D (w/out Desk 23" W), Approx. 300 lbs.

Dilution Air Cleanup Package 60"H x 21"W x 13"D

Approx. 60 lbs.



GE or Allen Bradley PLC, C3io provides data buffering, digital inputs, digital outputs, analog inputs,  analog outputs, and Ethernet communications. Optional HMI provided for manual system control.



Model Number T300, U, M, H for CO

Model Number T200, M, H for NOX

Model Number T100, H for SO2

Model Number T360, M for CO2

An optional Zirconia Oxide sensor can be added to the probe



CO            0-100 to 0-10000ppm

NOx           0-50 to 0-5000ppm

SO2           0-50 to 0-5000ppm

O2             0-25%

CO2           0-20%



± 20% of Reference Methods for 40 CFR 60

± 7.5% (better than ± 10.0%) of Reference Methods for 40 CFR 75



Less than 90 seconds to 95% full scale from system inlet



Zero and Span

± 0.5% absolute for O2/CO2%         

± 2.5% of full scale for NOX, and SO2 ppm

± 5.0% of full scale for CO ppm


REPEATABLILITY:  ± 1% of full scale

PROCESS:  80-1800°F, up to 35% moisture

AMBIENT:  65-80°F, 35% RH, no direct sunlight

SYSTEM UTILITIES:  40°F dew point instrument air, 80 psig minimum, 2 SCFM

Per probe, 240Vac, single phase, 60 hertz, 50 amp power



  • Regulatory Consultation
  • LightHawk® 560 Opacity Monitor integration
  • LaserHawk® 360 Particulate Monitor integration
  • Ultraflow 150 Ultrasonic Stack Flow integration
  • Automatic Linearity's
  • RegPerfect® Data Acquisition System
  • Training
  • Installation supervision
  • Startup
  • EPA certification
  • Maintenance Contracts


  • Coal, wood, and oil fired combustion
  • Refuse and medical waste
  • Processes with corrosive gases with high particulate loading and high gas concentrations


CEMS_Application_Setup.pdfCEMS_Application_SetupJon Adams


​The following table provides a list of items that need regular maintenance to ensure your product remains in good working condition.  See manual section 8 for detailed instructions and appendix A for checklists.
Description Weekly Monthly Quarterly Yearly
Recalibrate the analyzers X      
Inspect sample pump   X    
Inspect NOx exhaust pump   X    
Replace O3 scrubber media     X  
Clean dilution sample line       X
Rebuild sample pump       X
Rebuild NOx exhaust pump       X
Analyzer Maintenance (refer to individual analyzer manual) X X X X
Inspect probe filter and gaskets   X    
Inspect dilution sample line for condensation or particulate build up   X    
Inspect probe straw   X    
Inspect all valves and tubing X      
Inspect instrument air coalescing filter X      
Analyzer particulate filter X      
Rebuild CO2 Absorber       X
Rebuild CO Scrubber       X
DAS Server (refer to DAS manual)     X  
Replace Smoke/Heat Alarm 9VDC Battery     X  
Refill Charcoal Scrubber Media       X​