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Odorant analyzer

Odorant Analyzer

Simplify the odorization process using the most reliable odor/mercaptans monitor. The OMA is a solid state solution for replacing or supplementing human sniffers.

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  • Fast, continuous reading
    Analyzer response time is 1 to 5 seconds
  • No false positives
    Interfering chemicals can be corrected for by AAI’s multi components algorithm*
    *Provide sample matrix to AAI for verification
  • Huge dynamic range
    Remains accurate through wide changes in concentration

Utilize Rich Data

  • Rich trend data
    High measurement frequency paints a clearer picture
  • Measure up to 5 chemicals
    Individual concentration reading for each odorizing agent
  • Also measure H2S, COS
    Complete gas quality information


  • Unattended operation
    Stabilized by Auto-Zero; remote operation optional
  • Inherently safe design
    Sample fluid never enters analyzer enclosure Learn more
  • Customizable alarms & outputs
    4-20 mA analog outputs; MODBUS; Hart... View technical specs

Cost of Ownership

  • No consumables/reagents
    Other than zero fluid
  • Proven low-mainentance
    Only requires monthly optics cleaning
  • Long-life xenon light source
    Averages 5 years between replacement
  • Solid state instrument
    Outlasts competing models due to lack of moving parts


  • Hazardous area certifications
    Class I Div 1 & 2; ATEX; GOST... View certifications
  • No shelter required
    Rugged instrument suitable for outdoor installation


Odorants are added artificially to natural gas to allow for human leak detection. Local distribution companies (LDCs) employ numerous “sniffers” who judge odorant level in the natural gas product, while generating data from field reports, customer input, and modeling programs.

However, interstate pipelines span hundreds of miles that cross through various territories. Dispatching “sniffers” across vast distances is both time-consuming and costly. While “sniff testing” complies and satisfies the minimum criteria set forth in CFR, Title 49, Part 192.625, an on-line process analyzer would provide the same testing functionality with much richer quantitative data (one example: continuous trend data as opposed to discrete data points).

On-line odorant analysis allows the transmission companies to schedule the minimum required visits to perform sniffing, and optimize their odorant distribution system in real-time. Secondary benefits allow them to optimize their pipeline performance by studying lag times, odorizer performance, fading effects, and other odorant issues.

The OMA measures various odorants including:

  • methanethiol | methyl mercaptan | MeSH
  • ethanethiol | ethyl mercaptan
  • tetrahydrothiophene | THT
  • tert-butylthiol | tert-butyl mercaptan | TBM
  • proprietary odorants
    • SPOTLEAK® 1009
  • hydrogen sulfide | H2S
  • carbonyl sulfide | COS
  • mercaptans / thiols (total)

The analysis background for odorant measurement is typically a hydrocarbon gas stream. Common applications for the OMA Odorant Analyzer include:

  • natural gas
  • biogas
  • landfill gas
  • liquefied petroleum gas | LPG
  • syngas


Principle of Operation

To analyze the chemical composition of the sample, the OMA uses an analysis method known as ultraviolet-visible (UV-Vis) spectroscopy. The system measures absorbance from 200nm to 800nm and quantifies the amount of light absorbed by the sample at each integer wavelength; the OMA plots this raw data to visualize a high-resolution absorbance spectrum. Learn more

Spectrophotometer Principle of Operation

The OMA uses a long-life xenon light source to transmit a signal through the sample fluid in the flow cell. The signal is carried by fiber optic cables from the analyzer to the flow cell, where the chemical mixture of the sample has unique interactions with the light based on its current composition. Learn more

Optical Assembly

Odorant Absorbance Curves

To measure the concentration of an odorant (e.g. methyl mercaptan), the OMA detects the distinctive absorbance curve of pure methyl mercaptan and mathematically isolates this structure from the total sample absorbance. In accordance with Beer-Lambert Law, the OMA correlates the height of this curve directly to real-time mercaptan concentration.

Absorbance Curve: Methyl Mercaptan

Absorbance (AU)
Wavelength (nm)

User Interface

Our proprietary ECLIPSE software processes the raw spectral data to provide real-time concentration readings. The operator can easily navigate between views (trendgraph, spectrum, and more) using intuitive touch-screen navigation. You can also configure alarms, data logging, and outputs. Learn more

ECLIPSE software

Inherent Safety

Most analyzers draw the process sample directly into the analyzer enclosure for analysis, which is dangerous if the sample fluid is toxic, explosive, or corrosive. The OMA design is unique: we bring the light to the sample, not the other way around. The sample circulates through the external flow cell, which receives the signal via fiber optic cables. Learn more

Analyzer Safety

Technology Comparison

Below we compare the OMA Odorant Analyzer against another prominent method, gas chromatography.

Click any cell or row for more information.

Gas Chromatograph OMA Odorant Analyzer
Response Time?  SLOW  FAST
GC's will, under best conditions, have a sampling time of 30 seconds to one minute.
The OMA Odorant Analyzer has a total system response time of under 10 seconds. This allows for richer trend data and tighter process control.
Capital Cost?  HIGH  LOW
GC systems are notoriously expensive and require highly trained personnel to operate.
The OMA Odorant Analyzer costs less than half of a typical GC solution. No special personnel are required due to a low learning curve.
Maintenance/Downtime?  HIGH  LOW
A GC requires a lot of consumables and experienced maintenance technicians.
The OMA Odorant Analyzer is a solid state instrument with no moving parts. There is no regular downtime aside from the periodic Auto-Zero, a 60-second self-blanking procedure. Preventative maintenance only includes a monthly cleaning of the optics.
Specifications found in product literature from mainstream manufacturers.


All OMA models are equivalent in function and performance with identical electronic configurations. The models vary by form factor and materials of construction, each intended for a unique use case.



Wall-mounted process analyzer

  • Indoor/outdoor use
  • ATEX, Class I Div 1/2, GOST...
Learn more


Suitcase process analyzer

  • Carry from site to site
  • Rugged suitcase enclosure
Learn more


Rackmount process analyzer

  • Fits standard 19" rack
  • Ideal for lab/shelter
Learn more

Explosion-Proof Models

The OMA-300 is offered in two explosion-proof formats:

Exp (Purged) Explosion-Proof OMA-300


Eexp systems are purged and pressurized using a certified air-purging device. This method ensures that toxic/explosive gas is not allowed to accumulate inside the enclosure and is ideal when instrument air is available.

Exd (Cast Aluminum) Explosion-Proof OMA-300


Eexd systems are contained within certified explosion-proof cast-aluminum enclosures. This method is more practical if the installation is remote or utilities are unreliable.


The OMA is built for direct analysis of the hot/wet sample, thus simplifying the scope of the sample system and retaining high sample integrity. From our vast experience in sampling design, we know that applications can be similar but are rarely identical. For this reason, we design and build sample conditioning systems on a project basis, working from the process to the drawing board.


Note: All performance specifications are subject to the assumption that the sample conditioning system and unit installation are approved by Applied Analytics. For any other arrangement, please inquire directly with Sales.

Measurement Principle Dispersive ultraviolet-visible (UV-Vis) absorbance spectrophotometry
Detector nova II™ UV-Vis diode array spectrophotometer
Spectral Range 200-800 nm
Light Source Pulsed xenon lamp (average 5 year lifespan)
Signal Transmission 600 μm core 1.8 meter fiber optic cables
Other lengths available
Path Length Application-dependent
Sample Conditioning Custom design per application
Analyzer Calibration If possible, analyzer is factory calibrated with certified calibration fluids; no re-calibration required after initial calibration; measurement normalized by Auto Zero
Reading Verification Simple verification with samples and self-check diagnostic
Human Machine Interface Industrial controller with touch-screen LCD display running ECLIPSE™ Software
Data Storage Solid State Drive
Analyzer Environment Indoor/Outdoor (no shelter required)
Ambient Temperature Standard: 0 to 35 °C (32 to 95 °F)
Optional: -20 to 55 °C (-4 to 131 °F)
To avoid radiational heating, use of a sunshade is recommended for systems installed in direct sunlight.
Sample Temperature Standard: -20 to 70 °C (-4 to 158 °F)
Optional: up to 150 °C (302 °F) with cooling extensions
Contact AAI for temperatures above 150 °C (302°F)
Sample Pressure Using standard flow cell: 206 bar (3000 psi)
Electrical 85 to 264 VAC 47 to 63 Hz
Power Consumption 45 watts
Standard Outputs 1x galvanically isolated 4-20mA analog output per measured analyte(up to 3; additional available by upgrade)
2x digital outputs for fault and SCS control
Optional Outputs Modbus TCP/IP; RS-232; RS-485; Fieldbus; Profibus; HART;
Select analyzer type: OMA-300 Wall-Mounted Analyzer
OMA-206P Portable Analyzer
OMA-406R Rackmount Analyzer
Methyl Mercaptan Accuracy
Example ranges below. Custom ranges available. Accuracy may be higher at higher pressure.
0-10 ppm (@10 bar):  ±0.1 ppm
0-10 ppm (@1 bar):  ±1 ppm
0-100 ppm:  ±1% full scale or 1 ppm*
0-10,000 ppm:  ±1% full scale
0-100%:  ±1% full scale
*Whichever larger.
Standard Design General Purpose
Available Options ATEX, IECEx, EAC, PESO, JPN
Please inquire with your sales representative for additional certifications (CSA, FM etc.).
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