Laser 3 Plus Environmental

EPA PS18 compliant NH3 CEMS analyzer – avoids costly downtime and fines

A key part of our three-phase strategy for clean air, the Laser 3 Plus Environmental is our latest solution for accurate ammonia (NH3) measurements in DeNOx processes. It also meets all uptime and performance requirements for the US EPA PS18 standard, for reliable CEMS monitoring of NH3 as a precursor to harmful particulates.

  • Change is in the air with revolutionary TDL gas analysis
  • Low maintenance, low cost-of-ownership
  • EPA-compliant CEMS monitoring

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Your analyzer will be assembled in one of our state-of-the-art engineering centers and rapidly dispatched to your site

A fast-response measurement for ammonia slip

Rhys Jenkins
Rhys Jenkins
IP&E Spectroscopic Product Manager

The SERVOTOUGH Laser 3 Plus Environmental is a revolution in Tunable Diode Laser (TDL) Absorption Spectroscopy analysis: a highly compact gas monitor for in-situ cross-stack applications, which delivers exceptional performance benefits for clean air processes.

Installed directly into process ducts, it is ideal for monitoring ammonia slip during NOx reduction processes such as Selective Catalytic Reduction (SCR) or Selective Non-Catalytic Reduction (SNCR), controlling the level of ammonia slip to between 2-3 parts per million.

Delivering an average measurement of NH3 across the duct, it returns precise readings even during inconsistent flow conditions. With auto-validation software available to ensure ongoing accuracy, the Laser 3 Plus Environmental provides industry-leading installation flexibility and cost and performance benefits.

Change is in the air with revolutionary TDL gas analysis

Combining the latest advances in hardware with leading-edge software processing, the SERVOTOUGH Laser 3 Plus is a revolutionary step forward for TDL gas analysis in clean air strategies for industries around the world. Fast-response ammonia sensing is supported by advanced auto-validation software that ensures ongoing accuracy, making the analyzer ideal for NOx reduction processes. It provides unparalleled installation flexibility, along with significant cost and performance advantages that will benefit plant and refinery clean air strategies.

Service team checklist

Low maintenance, low cost-of-ownership

The next-generation ethos of the Laser 3 Plus works hard to reduce costs at all stages. In addition to the immediate advantages of TDL technology – a non-depleting measurement which requires no sample conditioning system – the Laser 3 Plus compact design greatly reduces installation time, with small, light intuitive alignment for easy installation and maintenance. It has full ethernet communications for commissioning, diagnostics and trouble shooting.

SERVOTOUGH Laser 3 Ammonia

EPA-compliant CEMS monitoring

The reliability of the Laser 3 Plus Environmental, supported by its auto-validation software capabilities, is essential to maintaining an uptime of better than 90%, overcoming the regulatory challenges of CEMS applications. It meets or exceeds all EPA PS18 NH3 requirements – the template for all future regulations for optical-based CEMS analyzers – and will successfully pass field verification tests. Manual or automatic daily QA/QC validations can be performed, with onboard alarms alerting when the analyzer is malfunctioning, in calibration, or above the applicable limit.

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Looking to boost your clean air strategy? We can help

If you need a gas analysis system for your DeNOx application, emissions control and monitoring, or any other application, get in touch with our experts. We provide the process knowledge and engineering skills you need to see your project through to a successful conclusion.

See the benefits for your clean air strategy

The compact Laser 3 Plus Environmental TDL analyzer is specifically optimized for the fast, accurate and responsive measurement of ammonia (NH3) in NOx reduction processes.

A reliable measurement

Servomex’s own line lock cuvette technology and auto-validation software ensure the analyzer continues to measure ammonia reliably.

Easy to use

The compact Laser 3 Plus Environmental is simple to install, with a user-friendly interface and range of digital communications options.

Hazardous area approvals

The Laser 3 Plus Environmental meets ATEX, IECEx and North American hazardous area approvals, and is IP66 and SIL 2 rated.

Unrivalled performance

  • Process temperatures up to 500°C *
  • Low detection limit
  • Negligable zero drift
  • Auto-validation capability
  • Calibration every 6-12 months

* Application and measurement dependent


  • Compact design
  • Performs in high particulate environments
  • Path lengths from 0.7m to 10m
  • Minimal cross interference
  • Diverse mounting: ideal for ducts, stacks and reactor installations

Easy to use

  • Simple to install and operate
  • Robust and reliable
  • Space saving
  • Digital communications
  • Modbus over Ethernet
  • User friendly interface and rapid disconnect for easy calibration

Low cost of ownership

  • Intuitive alignment for easy installation and maintenance
  • Non-depleting TDL technology
  • No moving parts, no consumables
  • No sample conditioning system – reduced maintenance costs
  • No hazardous area purge required

Benchmark compliance

  • ATEX, IECEx hazardous area approvals
  • North American hazardous area Class 1 Div 2
  • Meets EPA Performance Specification 18 for NH3 CEMS
  • Certified for gases and dust
  • IP66
  • CE approved

The SERVOTOUGH Laser 3 Plus Environmental delivers exceptional TDL performance, with a fast response to measuring ammonia in DeNOx applications.

Gas Measurement
Ammonia (NH₃)ppm


Tunable Diode Laser
SERVOTOUGH Laser 3 Ammonia


  • ATEX Cat 3 (Gases)
  • IECEx Zone 2 and Zone 21
  • North American Class 1 Division 2 and Zone 2 (Gas and Dust) pending
  • ATEX Cat 21 (Dust)
  • Safe Area / General Purpose
  • CE marked in compliance with ATEX, EMC, LVD and all other applicable directives

Schematics (select to expand)


131mm width (51/8”) 164mm high (61/2”) 302.4mm deep (119/10”)

110mm width (45/16”) 146mm high (53/4”) 247.6mm deep (93/4”) 


TRANSMITTER: <3.0 kg (6.6 lbs)

RECEIVER: <2.0 kg (4.4 lbs)

Get the detailed specifications

“For in-depth specifications you’ll want to download our technical datasheet which includes information on technology, performance, operating environment, sample conditions and compliance along with technical drawings and top-level benefits and applications.”

Rhys Jenkins
Rhys Jenkins
IP&E Spectroscopic Product Manager

Download your complete resource pack for the Laser 3 Plus Environmental

“Find out everything you need to know about this compact, fast-response TDL analyzer for clean air DeNOx strategies.  Our Laser 3 Plus Environmental resource pack contains the product brochure, operator manual, and other essential materials.”

Rhys Jenkins
Rhys Jenkins
IP&E Spectroscopic Product Manager

Manuals and brochures

For key information about the features, benefits and technical specifications of the Laser 3 Plus Environmental, download the operator manual and product brochure.

SERVOTOUGH Laser 3 Plus Environmental Product Brochure

Download the SERVOTOUGH Laser 3 Plus Environmental Brochure to find out more about this product.

SERVOTOUGH Laser 3 Plus Environmental Product Brochure

Download the SERVOTOUGH Laser 3 Plus Environmental Brochure to find out more about this product.

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SERVOTOUGH Laser 3 Plus Product Configuration

Get diagrams and configuration data for our TDL analyzers and accessories

SERVOTOUGH Laser 3 Plus Product Configuration

Get diagrams and configuration data for our TDL analyzers and accessories

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SERVOTOUGH Laser 3 Plus Certification Manual

Analyzer certifications and declaration of conformity

SERVOTOUGH Laser 3 Plus Certification Manual

Analyzer certifications and declaration of conformity

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SERVOTOUGH Laser 3 Plus Operator Manual

How to install, calibrate and use your TDL gas analyzer

SERVOTOUGH Laser 3 Plus Operator Manual

How to install, calibrate and use your TDL gas analyzer

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SERVOTOUGH Laser 3 Plus Environmental Recommended Spares

See the recommended spares list for the Laser 3 Plus optimized for ammonia

SERVOTOUGH Laser 3 Plus Environmental Recommended Spares

See the recommended spares list for the Laser 3 Plus optimized for ammonia

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SERVOTOUGH Laser 3 Plus Product Brochure

Download the SERVOTOUGH Laser 3 Plus Product Brochure to find out more about this product.

SERVOTOUGH Laser 3 Plus Product Brochure

Download the SERVOTOUGH Laser 3 Plus Product Brochure to find out more about this product.

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See for yourself

Our videos give you the chance to watch our products in action and hear from our experts. You can also see our analyzers unboxed, and find out more about our solutions for key applications

Lasers for Safety and Process Control

Learn about the role of the SERVOTOUGH Laser 3 Plus in fired heater combustion

Ammonia Slip Applications

See how the SERVOTOUGH Laser 3 Plus provides an analytical solution for this application

Laser 3 Plus Installation

Our expert demonstrates how easy it is to install the Laser 3 Plus


See the compact, fast-response performance of this innovative analyzer 

Unboxed: SERVOTOUGH Laser 3

Watch our expert Product Specialist Luke Purdie unpack this innovative TDL gas analyzer and explain its features and benefits in a range of applications.

In this episode, application experts discuss gas analysis for continuous ammonia (NH3) monitoring in combustion emissions.


RJ: Hello, my name is Rhys Jenkins, and I’m the product manager for spectroscopic analyzers at Servomex. In this podcast, we’ll be reviewing the PS18 requirements in the United States for the measurement of ammonia in stack gas. With me today to help with this discussion is a guest speaker, and a former colleague of mine, Barbara Marshik. And we will listen to Barbara as she describes the situation in the US with PS18. Barb, will you introduce yourself?

BM: Thanks for the introduction, Rhys. I just wanted to let you know, thanks very much for inviting me for this podcast. I’ve spent more than 25 years working at really small and also large firms, mainly looking at global market strategies, developing some new products, applications, mostly for the environmental emissions, a little bit into the industrial processes and started my career out in industrial gas markets. As Rhys said, I was recently working for Servomex and, in July, 2021, I left Servomex to start my own marketing consulting firm called Gas Marketing Consulting.

And from that, I’m working with several different clients, looking at strategic commercial and technical content for, basically, product positioning and enhancements technologies and reviewing key risk factors within the desired market space. In particular, I have done quite a bit of work looking at and investigating the ammonia market within the United States.

RJ: Thank you Barbara. So, we make a start by looking at: why is there a need for the measurement of ammonia in continuous emissions monitoring systems in the US?

BM: Yeah, this is something that’s just starting to come into the marketplace. Ammonia itself is not a criterion pollutant and it also isn’t regulated as a hazardous air pollutant by the US EPA. This is all done under the Clean Air Act. But even so, a lot of the states are starting to look at ammonia as a precursor to particulate matter of 2.5 microns, or what you will hear as PM 2.5. PM 2.5 is regulated, however. The states are viewing this as: if you can stop the precursor, you can actually lower your PM 2.5 emissions, and that’s why people are looking at ammonia for CEMS, right now.

RJ: Thank you Barb. So, where are all the ammonia continuous emissions monitoring systems being implemented?

BM: In general, a lot of the states are starting to target the large stationary and area source facilities. Most of those are required to meet really low NOx limits. NOx in itself – nitrogen oxides – is a criterion pollutant and it is regulated. And, in those cases, they all had to deploy some kind of DeNOx process and put in equipment that reduces the NOx, using either a selective catalytic reduction or selective non-catalytic reduction, SCR or SNCR. And those have been deployed into those stationary and area sources.

In the DeNOx process, an excess amount of ammonia is actually required. It’s either ammonia or it comes from urea, and that’s used to reduce the NOx to, basically, nitrogen and water. And again, it’s either done with or without a catalyst. The use of the excess ammonia ensures that the NOx is going to be fully reduced, and that’s where this ammonia problem starts to become possibly an issue with PM 2.5 – it’s also a problem with smell.

The DeNOx equipment is typically employed at the emissions from a power generator, and that includes anything that’s gas-fired, such as turbines, and you’re going to see them deployed on really large process heaters that are found at many of the chemical plants.

RJ: Now we know the why and the where, what are the requirements for these emissions monitoring systems?

BM: Yeah, so that’s kind of a tricky question. The requirements are really all over the place, because, again, this is not regulated by the US EPA. For instance, in the state of California, they’re looking at even lowering the NOx emissions from what the EPA standards are set to; they’re looking at limits down to two or two-and-a-half ppm of NOx. And in fact, they’re looking at adding a five to 10 ppm ammonia limit in some new regulations that they’re promulgating. And again, they’re looking at setting these up for large stationary area sources, especially and in particular, those that use an SCR or SNCR catalyst.

The state of Texas, the TCEQ, has also been adding ammonia emissions to permits of several large stationary area source facilities. So, if a facility decides to add a fairly large-capacity heater, they’ve been targeted to add ammonia emissions – and also to fairly large greenfield projects. So now, while the states have decided to regulate ammonia emissions on their own, the problem still is that the US EPA doesn’t regulate it.

And again, there’s no real specification for what kind of analyzer you use, how you verify that it actually works, and so it’s really up to the states that are designing and writing their own requirements. So that brings up an issue because, without a federal mandate, a lot of the facilities are actually worried that if they do install an ammonia monitoring equipment, and it performs up to whatever the state’s requirements are, what happens in the future if the EPA starts to establish a different performance specification?

So, about a year ago, that’s when the US EPA finally stepped in and strongly recommended that the regions follow their guidance. And that guidance has been that the state should look at the Performance Specification number 18, or PS18. Originally it was written for hydrochloric acid, or HCl, but it was really intended to be the template for all future regulations that the EPA was going to write for anything that was optical-based, and those optical-based systems that were going to be placed in a CEMS.

So, this is the guidance that manufacturers like Servomex are actually following, to validate that their analyzer will perform right now, as well as in the future, if EPA does decide to regulate ammonia.

RJ: What do you consider to be the most applicable optical methods?

BM: There’s a real push for both the power industry, as well as the chemical processing industry, to install tunable diode lasers. And, in particular, the focus is that once it’s installed, it has extremely low maintenance – and it’s also very easy to install.


Once it’s actually into a CEM system, the tunable diode laser can easily be added as the next component that has to be measured. So rather than putting in a whole new CEM system, putting up a tunable diode laser on your stack is quite easy. You tag that system right back to your data acquisition system, and now you’ve got a tunable diode laser system deployed.

This is actually the newest and the most prevalent optical-based analyzer that’s being used in the CEM system as we speak. It’s been used for over 20 years in the process industry, monitoring gases, and it’s just recently been installed into the emissions monitoring CEMS market.

RJ: Thank you, Barb. Well, that summary leads us very nicely on to the Servomex Laser 3 Plus tunable diode laser. As Barbara mentioned, the market is looking towards the laser-based optical methods to do the ammonia measurement, primarily doing it as an in-situ, cross-stack measurement, as opposed to a more traditional extractive method, though it will work in both options.

The Servomex Laser 3 Plus has a number of advantages when it comes to the implementation into ammonia emission systems and the requirements that have been imposed by states like California to meet the PS18 validated ranges. The Laser 3 Plus has ranges that go from zero to 10 ppm all the way to zero to 100 ppm ammonia, which means it’s ideal for either the slip or the emissions market.

Testing has shown it to exceed the performance of the requirements within PS18, and this is especially with the interference of moisture on the ammonia reading, where it can be very tricky to do the ammonia reading at low levels where you get moisture interference coming into the ammonia absorption range.

The long-term stability of products like the Servomex Laser 3 Plus gives a long-term uptime of greater than 95%, so a very low-maintenance product. Of course, the regional requirements will dictate how often the measurement is validated at which the unit has an external validation cell, flow-through gas type.

The rapid service response offered by Servomex within the US market now includes the hot-swap units, which is: if a unit is not repairable in the field, Servomex will swap it out for an exact replacement unit that will be installed for the period where the repair takes place. The repair should take place within the US, at this point, and the idea is that we will get your analyzer back to you with minimal downtime.

The unit comes, obviously, fully installed with alarms, and relay functions, and milliAmp functions, diagnostics capability to give pre-warning of out-of-specification readings, and for anything that is above the defined ammonia limit for your process.

The automated software within the analyzer is good for daily quality assurance and quality tests. The idea is that the Laser 3 Plus would integrate smoothly into any existing CEM system.

All that remains for me is to thank everyone for listening to this podcast and special thanks to our guest speaker Barbara Marshik for her great overview of the ammonia CEMS market in the US and the requirements of PS18.

For anybody who would like further information on Servomex, more Servomex products, or especially the Laser 3 Plus Environmental for the measurement of ammonia, please visit, or contact your local Servomex representative. Thank you.

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