SERVOTOUGH SpectraExact 2500F

Achieve accurate liquid water analysis in tough environments

The SERVOTOUGH SpectraExact 2500F brings a new level of precision for liquid water analysis. Its rugged, reliable, and user-friendly design requires minimal maintenance. This iconic, industry-leading photometric analyzer from Servomex is capable of measuring liquid water in acetic acid, acetone, EDC, glycols and more, making it ideal for a range of process, combustion, and emissions gas analysis applications.

  • Flexible, real-time, online process analysis
  • Accurate and reliable ppm to percent level measurements
  • Ideal for liquid water analysis in EDC, acetic acid, and acetone
  • Handles corrosive, toxic and flammable streams
  • User-friendly interface and minimal maintenance

Ready to buy? Here’s how it works

It’s easy to find the product you need for your application with Servomex


Get in touch to tell us what you need and the application you plan to use it for


Our expert team will help you select the right product package, ensuring you have the accessories and support to get the best performance from your analyzer


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

Real-time photometric analysis of flammable gas streams

Rhys Jenkins
Rhys Jenkins
IP&E Spectroscopic Product Manager

Designed to provide a highly flexible analytical solution adaptable to many applications, the SpectraExact 2500 delivers a winning combination of proven performance and flexible operation in a resilient and reliable design.

It adapts to your process effortlessly to deliver a real-time online monitoring solution. Field mounting capabilities enable flexible use in the harshest process conditions.

Highly affordable and easy to use, the SpectraExact 2500 uses an intelligent design and non-depleting sensing technologies to help to extend maintenance intervals and dramatically reduce ongoing costs.

Enhanced safety for the most dangerous locations

When you work on applications with complex process application requirements, you need a highly flexible, easy-to-use solution that is adaptable to your exact process specification monitoring needs.

More features, more flexibility

Building on the proven measurement principles of Servomex’s premium NDIR analyzers, the SpectraExact 2500 offers an exceptional range of options to meet your specific application needs.

Digital communications platforms enable the full functionality of the SpectraExact to be controlled remotely and safely, with Modbus implemented through MODBUS TCP.

Options include a High Integrity cell, supplied with specialist Chemraz “O” rings to ensure improved leak tightness for use in high concentration, highly toxic gas measurements. Meanwhile a heated cell is a standard option available on safe area, ATEX, UKEx, IECEx, and North American class 1 division 2 variants.

Member of Service team walking to analyzer

Unbeatable value over product life

The ability to reduce ongoing costs and leverage maximum efficiency from safety equipment is essential to your business. This is why SpectraExact features an intelligent design that helps to reduce the frequency of maintenance requirements via sample cell and electronics segregation. This, combined with the use of non-depleting NDIR photometric sensing technologies, ensures the SpectraExact delivers a long life of performance with a low lifetime cost-of-ownership.

Man with Servomex System components

Building a system? We’re here to help

Do you need a gas analysis system? Get in touch with us before you start. We have the experience, expertise and engineering skills to see your project through to the end.

The benefits of photometric process monitoring

Flexible and resilient, the SpectraExact 2500 delivers proven results, even in harsh process conditions.

Safe operation

The SpectraExact 2500 uses non-contact analysis techniques, with the sample cell segregated from the electronics for ease of maintenance and safety.

Flexible integration

The SpectraExact 2500 offers an exceptional range of options, including digital communications that allow safe, remote control of its full functionality.

Enhanced for dangerous locations

Flexible and adaptable, the SpectraExact 2500 will be certified for safe area, with IECEx and North American hazardous area approvals.

Unrivalled performance

  • Suitable for mounting in hazardous area locations
  • Highly reliable, accurate and stable


  • On line, real time analysis

Easy to use

  • Modbus TCP (Ethernet) options
  • Ideal for diverse gas sample types (0-180°C/32-356°F and 0-150psig/0-10barg/0-1,000kPag)

Low cost of ownership

  • Separate cell allows simple cleaning and servicing
  • Field proven non-depleting technologies

Benchmark compliance

  • ATEX, UKEx, IECEx and North American hazardous area approvals

  • Certified for gases and dust

  • Certified to measure a continually flammable sample

Highly flexible, the SpectraExact 2500 provides single and multi-component gas analysis in flammable streams. Download the product brochure for a full list of available measurements.

Gas Measurement
Ammonia (NH₃)%
Carbon monoxide (CO)%, ppm
Carbon dioxide (CO₂)%, ppm
Hydrogen chloride (HCL)%
Methane (CH₄)%
Hydrocarbon mixtures (C₁-C₅)%
Nitrous oxide (N₂O)%, ppm
Propane (C₃H₈)%
Total Hydrocarbons (THC)%
Water vapour (Moisture) (H₂O)%
Nitric oxide (NO)%, ppm


Gas filter correlation Infrared


  • North American Class 1 Division 2 Group A, B, C, D T4 (certification pending)
  • IECEx Zone 2 T4
  • ATEX Cat 3 T4
  • UKEX Cat 3 T4
  • Electrical safety to IEC 61010-1
  • Demonstrates analyzer hardware compliance to SIL 2, IEC 61508 (application dependent)

Schematics (select to expand)


Max: 1,620mm (63.7”) Width x 500mm (19.6”) High x 284mm (11.1”) Deep


27kg (55lbs) to 50kg (110lbs)

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

The information you need, all in one download

“The flexible SpectraExact 2500 provides accurate measurements for so many gas components that we couldn’t list them all here. For all the features, benefits and technical specifications, including a comprehensive list of measurements, download our resource pack now.”

Rhys Jenkins
Rhys Jenkins
IP&E Spectroscopic product Manager

Manuals and brochures

Want more information about the SpectraExact 2500? Download our operator manual and product brochure, and get the details you need.

ALL NEW SERVOTOUGH SpectraExact 2500F Product Brochure

Find out about our adaptable Photometric process monitoring analyzer

ALL NEW SERVOTOUGH SpectraExact 2500F Product Brochure

Find out about our adaptable Photometric process monitoring analyzer

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ES Magazine Issue 37 Clean Air Part 2

An expert look at our gas analysis solutions for clean air strategies and carbon capture technologies.

ES Magazine Issue 37 Clean Air Part 2

An expert look at our gas analysis solutions for clean air strategies and carbon capture technologies.

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SERVOTOUGH SpectraExact 2500 – Approvals, Certificates & Conditions Manual

Download all the approvals and certificates for your SpectraExact 2500 analyzer

SERVOTOUGH SpectraExact 2500 – Approvals, Certificates & Conditions Manual

Download all the approvals and certificates for your SpectraExact 2500 analyzer

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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

SpectraExact 2500 quick start guide

Get your SpectraExact 2500 photometric analyzer up and running fast with this video guide

SERVOTOUGH SpectraExact 2500 upgrade video

See why you should upgrade your photometric gas analysis in our  SpectraExact 2500 video.

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An effective solution for hazardous environments

Carbon capture and storage

Extensive solutions for a range of carbon capture processes

Discover the secrets of the new SERVOTOUGH SpectraExact 2500. We discuss how this photometric analyzer’s dispersive Infrared sensing capabilities can be used in a wide range of applications.

Podcast transcript

SF: Good morning, good afternoon, good evening. Welcome to this Servomex podcast. I am Stephen Firth, and I will act as the host for this event. I am the business development manager looking after industrial process and environmental markets. I’ve been with Servomex heading towards 30 years, and deal mainly with our industrial products. I’m joined today by my colleague, Rhys Jenkins, and I’ll let Rhys introduce himself.

RJ: Hello. My name’s Rhys Jenkins, I’m the product manager for Servomex’s process spectroscopic analyzers. And I’m here today to introduce Servomex’s newest analyzer, the SpectraExact 2500, which is a non-dispersive infrared analyzer targeted at the process industry.

SF: As Rhys has indicated, this podcast will focus on the Servomex 2500 infrared analyzer. So Rhys, can you give me an overview of the 2500 as a product?

RJ: Yes, Stephen, the SpectraExact 2500 is a high-performance infrared analyzer that replaces Servomex’s previous 2500 series of analyzers which were first released in the early to mid-1990s. The old 2500 series has been a great success for Servomex, with a highly reliable and trusted measurement and well over 30 years of sales history. But it has become time for Servomex to replace the old analyzer with one that is more modern, and meets all the latest international standards requirements. So, we’ve designed a new analyzer that will give our customers the same high level of performance and reliability that they’re used to, while meeting today’s customer requirements for interconnectivity and intuitive use.

SF: I must admit, I have fond memories of the 2500 series. It was the first analyzer I worked on as a young applications scientist back in the in 1993-1994 region. And we’ve used this extensively on processes – for example, PTA, EDC, ethylene oxide, VCM – over the years, with great success. The customers like its reliability, its robustness, and its ability to deal with difficult corrosive and toxic samples. So, Rhys, how does the 2500F, the new model, differ from its older variants?

RJ: In many respects, you look at it as evolution rather than the revolution. With the 30 years of analyzers in the field and the experience we’ve gained from that, we’ve been very careful not to move away from a very proven technology and the proven good aspects of the older analyzer. For example, it is the same measurement principle, which is single-beam dual-wavelength. It still uses our own long-life source, infrared source, and a spinning chopper wheel, which I’ll talk about later on, containing the measurement reference filters. The cell design, we’ve kept that broadly the same as the old analyzer, because it’s very important for the integrity of the cell in flammable or toxic gases. So the cell that we’ve got at the moment has millions of hours of proven in-use data behind it, so we decided that we would not redevelop that.

In fact, if you’re already familiar with the old 2500 series, an existing user would identify many of the parts of the analyzer and the measurement as being the same, and would feel very comfortable looking inside the box and saying what the main parts are. We’ve also made sure that the new analyzer fits in the same footprint as the older analyzer. And we’ve kept the mounting fixings, the sample connections, and the wiring connections all the same to allow for a simple upgrade.

But this doesn’t mean that we haven’t made improvements. We have made many. Firstly, when you look at the new analyzer, the first thing you’ll notice is that it has a very large, new, intuitive user interface on it. This is based off our successful interfaces and displays that we’ve been utilizing on the process Paramagnetic and laser analyzers for, well, a decade and a half. So that was one of the first ones we wanted to improve because the old analyzer had a rather difficult user interface and was a little bit clunky to use.

Inside the box, it’s all new electronics. Everything from an electronic perspective is completely new, utilizing modern, readily available, industrial-specification components. The older analyzer, obviously, was using components that were modern 35 years ago, and we all know the world has changed very significantly since then, and many of those components are difficult to get hold of nowadays. Much of what was previously carried out in old analog electronics is now carried out in the digital world within microprocessors, and this has given us improvements in response time and significantly decreased sensitivity to electromagnetic interference, so it’s a more robust design, for a more modern age. Also, we’ve had to make the analyzer compliant with all the latest international standards, so that’s hazardous area certifications, EMC, Reach and ROS. So those requirements for new components and the new design, that is all covered in this analyzer.

The other focus was on communications and communication protocols, internal data logging and exportable, full alarm and maintenance histories, and things like that that help with the service side of the analyzer, as well as predictive, preventative maintenance, which is also required in a modern digital solution.

So we’ve gone a long way in modernizing what was a very trusted product, but we haven’t thrown away all good things in doing that. What we’ve done is made a product that will have many years of field life, maybe not the 30, 35 years of the old analyzer, but this analyzer will take us well into the next 20 years as Servomex’s high-end infrared analyzers.

SF: So, in summary, we’ve effectively taken the same technological concept, we’ve updated it with modern electronics, but it’s got essentially the same form, fit, and function as the original analyzer.

RJ: Yes, absolutely.

SF: So one question becomes… we have a large installed base, the 2500 has been out there for the best part of 30 years. From a user’s point of view, what’s the upgrade path? If you put in a new unit where an old unit was there, what would they have to change within their installation?

RJ: Well, currently the answer would be very little, if nothing. We’ve even kept the mounting fixings in the same places. So, with the variance in cell lengths, which can range from two millimeters to one meter, we’ve kept those mounting fixings the same. So you should be able to purge down and then decommission an old analyzer, disconnecting the pipework, disconnecting the cable glands, and then with minimal effort install a new analyzer onto the same mounting fixings, use the same cable entries, cable glands, if you so wish, you might have to do a little bit of trimming, but form, fit and function will be the same, the gas connections will be in the same place as they were on the previous analyzer. So very little to do in terms of replacement.

And then of course you have to commission it, set the milliamp outputs to the ranges you require, set any filtering alarm to the levels you want. But a like-for-like replacement is going to take an hour, rather than having to drill holes and put new studs in panels, find different cable, lay different cable, potentially with different screening, etc., etc. So it is a form-fit-function replacement.

SF: One of the advantages of the 2500 is its inherent flexibility. We can change the source, the optics, the detector, to measure a very broad range of gases and liquids in a variety of backgrounds. What are some of the key applications that we offer the 2500 for?

RJ: There’s a very broad range of applications. In fact, there’s many hundreds that over the years we’ve sold the analyzer to, dozens and dozens of gases, dozens and dozens of different ranges. The SpectraExact tends to get used in processes where customers are looking for a high quality and highly reliable or robust measurement is required. Reliability is key: this allows our customers to extend maintenance intervals. It’s a relatively maintenance-free analyzer as process gas analyzers go, but also, it’s trustworthy. And trustworthy is a word that I like to use because it brings together the whole feel of a product when it’s working well. You’ve got the measurement you can trust. You know that when you finish a shift on a Friday and over the weekend you will not be called out for emergency maintenance. It’s got that robustness to it, that means customers, operators, process engineers, service engineers feel trust in the measurement.

SF: Certainly I’ve made use of the 2500 on many of the industrial processes I come into contact with. This would be ethylene plants, ethylene oxide, ethylene dichloride, phosgene, PTA, and its flexibility helps from the point of view… You can use one analyzer across a wide variety of applications within a plant, and this clearly provides you with a common base. They all work the same way, the spares are the same, the functionality’s the same, the user interface is the same. And all of these help with the service and support, and the training required to get the best out of these analyzers on that broad range of applications.

RJ: Yeah, the technique can be used to measure many gases. You’ve mentioned quite a few there, but also you’ve got ammonia, carbon monoxide, carbon dioxide, methane, water vapor, total hydrocarbons, all in the mix, so it can do almost anything that’s thrown at it. All we have to do is select the measure and reference wavelength filters, and that’s really where the clever bit is, along with how we do some of the rather unique signal processing that gives us such a high performance, highly stable, very accurate measurement. And with it you can measure from percent levels to ppm levels depending on the gas you’re looking at.

As you mentioned, key processes, along with PTA, are things like ethylene and ethylene dichloride production, but we’re also looking now at getting into the carbon capture and decarbonization processes where, again, these are processes where they are installed down at the back end of a hydrocarbon or power process. Very often the operators don’t want to have high technical skills on-site, they don’t want to be having service engineers coming out to look at the decarbonization package. And the 2500, though there are many and varied other analyzers that will do the measurement as well, is the one that will last the longest, give the least maintenance, give the least trouble, and that’s really what it’s designed around.

You mentioned phosgene as one of the applications. Well, I’m sure listeners know that phosgene is an incredibly toxic gas, and when you extract phosgene from a process and put it through a gas analyzer like the 2500, you really want the integrity of all the pipework and integrity of the measurement cell, integrity of the optics, to be of the highest degree. And Servomex do very low leak rate versions of the analyzer with specialist gaskets and O-rings. And we have what we call an end box, which is essentially a purged area between the measurement cell and the analyzer electronics, so there’s no way you’re going to get a leak path of anything like phosgene or flammable gas into the enclosures on either end.

And it’s those added things that mark us as being a supplier that goes that one bit further. So the customers who can trust it to measure phosgene, that should really say something to other customers who are looking for a highly reliable gas analyzer, because you don’t get on these processes with anything else.

If you visit, you’ll get access to data sheets, videos, application videos, applications information, product guides, there’s a lot there, especially around this analyzer because it’s been in the company for so long, including the Servomex expert solution guides. There are just too many gases and applications to mention here, so I really do encourage people to go on to and see what the product has to offer.

SF: The details of this podcast are on the Servomex website, where you can find your local Servomex representative for when you want to contact us. So thank you, Rhys, for your time.

RJ: Thank you, Stephen, for this opportunity to talk about this exciting new analyzer from Servomex. As product manager, I’m certainly very excited to be launching this product.

SF: And I’d like to thank the listeners for being part of the launch of the Servomex SpectraExact 2500. I hope you’ve enjoyed this podcast and I look forward to you joining us on the next one. Thank you very much, and good morning, good afternoon, good evening. Thank you.


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