Systech Illinois EC91 ATEX O2 Analyzers

The ATEX-certified EC91 is an intrinsically safe oxygen analyzer that provides and transmits accurate oxygen measurements of gas streams in hazardous areas.


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Product Description

Brought to you by Systech Illinois, our specialist moisture, gas and oxygen analysis brand, the EC91 is an innovative gas analyzer and oxygen transmitter.

Our team at Systech Illinois has over 30 years of expertise in manufacturing gas analyzers for the process industry. They have an installed base of over a thousand instruments during this time.

The EC91 intrinsically safe oxygen analyzer is an online transmitter for ppm and percent oxygen measurements of gas streams in hazardous area installations. It can detect oxygen levels from as low as 1 ppm up to much higher percent levels and delivers results in most industrial gasses and atmospheres.

A versatile oxygen analyzer and oxygen transmitter

Whatever your gas analysis needs, the EC91 has got you covered! Here is just a flavor of the many applications it’s ideal for:
Monitoring inert blanketing gas in oil and petrochemical applications
Checking inert gasses and Hydrogen
Oxygen deficiency monitoring
Gas purity inspection
Glove box investigation
Gas line monitoring

An intrinsically safe gas analyzer

When you’re working in hazardous areas you need the best protection. You’ll find that oxygen analyzers and oxygen transmitters commonly need to be flame-proof, explosion proof or intrinsically safe.

Flame proof or explosion proof instruments are designed to contain any event, in order to protect the close environment. This equipment is expensive. Plus you’ll need a work permit to maintain and – in some cases – to calibrate it.

But intrinsically safe equipment like the EC91 gas analyzer is absolutely safe by design! There’s no risk of an event as there’s not enough energy stored, or available in the circuits to cause one, and work permits aren’t required.

Certified gas analysis protection

The EC91 gas analyzer is certified to IP66 standards. What does that mean? It means you’re protected with an IP (ingress protection) code which shows how well the device responds to water and dust. On top of this it also comes with NEMA 4X certification, a rating for an outdoor electrical enclosure. This means that the device is safe from damaging environmental conditions, including dirt, rain, ice formation, and corrosion.

All of the electronic circuits of the EC91 are also intrinsically safe, certified to ATEX – a European directive for controlling explosive atmospheres.

You can rest assured that the EC91 oxygen analyzer won’t let you down in the most hazardous environments. This even includes ATEX Ex II 1G EX ia IIC T4 Ga – Zone 0 areas.

A rugged oxygen analyzer

The EC91 gas analyzer’s enclosure is manufactured from molded glass fiber reinforced polyester. This is a high-impact resistance material for harsh environments.

Whether it comes up against oils, common acids or alkalis it won’t be harmed. We’re so confident in this gas analyzer that it comes with a 36 month warranty. This covers any faulty workmanship and electronic circuit card component failure.

A no fuss gas analyzer

Where possible, we like to simplify your working life! So, there’s no need for routine maintenance of the EC91 gas analyzer’s fuel cell. Plus the device can be easily calibrated, using ambient air or standard calibration samples.

The EC91 is built for your requirements

Whatever environment you need your oxygen analyzer or oxygen transmitter to succeed in, we can help.

Standard and custom designed sample systems, sample pumps and aspirators are available on request. Plus sample gas may be piped directly to the instrument or remote cell assembly.

An alarmingly safe gas analyzer

You can specify up to six gas measuring ranges and the EC91 transmits a 4-20mA signal which corresponds to the range of the analyzer. Additionally a safe area digital indicator and alarm is available as an option if you want it.

Gas analyzer and oxygen transmitter options

Across the Industrial Physics portfolio we have plenty of oxygen analyzers and oxygen transmitters. Also made by Systech Illinois, if you want an intrinsically safe portable oxygen analyzer then you might want to take a look at the EC92DIS.

If you need to invest in an oxygen deficiency monitor for continuous monitoring of O2 levels in confined spaces, storage food areas – or where low or high levels may pose a hazard to personnel – we’re sure you’ll appreciate the EC9031 oxygen analyzer.

We live and breathe oxygen analysis!

We’ve been in the business of manufacturing oxygen analyzers and oxygen transmitters for many decades now. Over the years we’ve learnt lots of best practice and we’re always pleased to share this with our customers.

Across the knowledgebase section of our website you’ll find blogs that describe the different types of oxygen analyzers, their uses and functions. You’ll also find industry specific write-ups including this one that explores the importance of gas testing in the medical industry, when lives are on the line!

The EC91 gas analyzer principle of operation

The EC91 gas analyzer has a self-powered sensor with no moving parts which is integral to the sample chamber.

This clever design solves the problem of output changes due to any flow rate change. This makes our oxygen analyzer extremely sensitive and quick to respond to changes in oxygen concentration.

The EC91 sensor contains an anode, electrolyte, and air cathode with a diffusion limiting capillary. The rate of diffusion is dependent upon the volume concentration of oxygen in the atmosphere or gas stream.

At the cathode of our gas analyzer, oxygen is reduced to hydroxyl ions, which oxidize the metal anode. The overall reaction that takes place looks a little like this!

2Pb + O2 + 2H2O → 2Pb(OH)2

The EC91 gas analyzer’s sensor has a guaranteed operational life of six months. But you can expect it to last much longer when checking low oxygen concentrations and when relying on it sporadically. Even if you need to swap a part, the sensor module is inexpensive and easy to replace.

We hope you’ll agree that our brilliant gas analyzer truly is a breath of fresh air!


  • SKU: 091 100
  • Applications: Gas Analysis and Testing
  • Materials: Gas
  • Gas: oxygen
  • Applications: industrial gas, intrinsically safe, oxygen deficiency
  • Measurement range: ppm and %
  • Technology: electrochemical gas analyzer
  • ATEX approval: 0
  • Measurement range: six selectable
  • Resolution: 0.05% of scale
  • Response time: 90% of reading within 20 seconds
  • Ingress protection: IP66, Nema 4X
  • Approvals: ATEX Ex II 1G EX ia IIC T4 Ga

Features & Benefits

  • Detect oxygen levels from as low as 1 ppm up to much higher percentages
  • Certified for Zone 0 hazardous areas
  • Maintenance free 5 year life sampling cell
  • Specify up to six gas analyzer measuring ranges
  • Unsurpassed safety protection
  • Air calibration oxygen analyzer facility
  • 3 year electronics warranty
  • A safe area digital indicator and alarm is available
  • Comes with a 36 month warranty covering faulty workmanship and electronic circuit card component failure

With over 40 years as an industrial equipment supplier JWII has a profound depth of knowledge in the space of analytical instrumentation and related solutions. We help and advise clients to navigate a broad spectrum of products their uses in industry to meet process control and sustainability goals . Our advanced array of tools, synergized with our team of specialists, enables us to deliver solutions of significant impact. With a legacy marked by consistent achievements, we hold in high regard our steadfast dedication to catering to an international clientele spanning diverse industries and geographies.

Our Premier Suite of Services Encompasses:

  • Installation: Precision-driven integration tailored to specific requirements.
  • Routine Maintenance: Ensuring systems’ longevity and optimal performance through regular oversight.
  • Repairs and Upgrades: Proactive identification and rectification of system inefficiencies, bolstered by the latest technological advancements.
  • Modifications to Current Installations: Adapting existing systems to align with evolving client needs.
  • Emergency Response Repairs: Prompt and efficient solutions for unforeseen system challenges.
  • Commissioning: Comprehensive system design, installation, testing, and maintenance to meet exacting operational standards.
  • On-site Assistance: Dedicated field teams providing hands-on support, ensuring seamless operations irrespective of challenges.
  • This field is for validation purposes and should be left unchanged.
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