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OMA-

Wobbe Index Analyzer

Fast, online measurement of fuel gas interchangeability (Wobbe) and stream composition using a fully automated, all-optical instrument.

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Performance

  • Direct Wobbe Measurement
    Unlike indirect residual oxygen analysis, the OMA optically measures the chemical composition of the fuel gas and outputs Wobbe Number and specific gravity
  • Fast, continuous reading
    Total response time under 10 seconds
  • InGaAs semiconductor technology
    Extremely stable performance

Reliability

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

Cost of Ownership

  • No consumables
    Other than nitrogen (zero gas)
  • Proven low-mainentance
    Only requires monthly optics cleaning
  • Solid state instrument
    Outlasts competing models due to lack of moving parts

Compatibility

  • Direct analysis of hot/wet sample
    Accepts sample up to 66 °C and 3600psig
  • Hazardous area certifications
    Class I Div 1 & 2; ATEX; GOST... View certifications
  • No shelter required
    Rugged instrument suitable for outdoor installation

Models

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-Mount

OMA-300

Wall-mounted process analyzer

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

OMA-206P

Suitcase process analyzer

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

OMA-406R

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

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

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.

Applications

The Wobbe Index (WI) expresses the heating value (known as calorific value) of gases used as fuels, taking into account the proportionality of calorific value to the specific gravity, or the density ratio between the given fuel gas and air. More precisely, the specific gravity is proportional to flow velocity through a constant orifice size at a constant pressure, and thus proportional to gas calorific value.

This measurement is important to operators because it can quickly determine the interchangeability of two or more fuel gas streams. At a flare or a custody transfer station, this measurement is a constant necessity.

Technology

Principle of Operation

To analyze the chemical composition of the sample, the OMA performs infrared spectroscopy using an InGaAs (indium gallium arsenide) sensor. The system measures absorbance from 1550 to 1850nm and quantifies the amount of light absorbed by the sample; the OMA plots this raw data to visualize a high-resolution absorbance spectrum.

The OMA uses a long-life tungsten 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

Sampling

The sample conditioning system for the OMA Wobbe Index Analyzer is a panel designed to achieve quick, automatic, and reliable Wobbe Index readings on pipeline-quality natural gas.

The panel includes the following parts:

  • NEMA 4 painted carbon steel enclosure
  • Density meter with absolute pressure sensor
  • Particulate filter
  • Pressure regulator on sample inlet
  • Pressure regulator on calibration gas inlet
  • Flowmeter for the sample inlet
  • Flowmeter for the sample bypass
  • Pneumatically actuated 3-way ball valve for automatic zero control
  • Manual 3-way ball valve for manual span control
  • Hazardous Area Rated Enclosure Heater
  • Check valve on the sample return

Wetted materials for the sample conditioning system include: SS316/316L, viton, PTFE, fused silica.

Specifications

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 InGaAs (indium gallium arsenide) infrared spectrometer
Detector nova II™ InGaAs Spectrometer
Spectral Range 1550-1850 nm
Light Source Tungsten lamp
Signal Transmission 600 μm core 1.8 meter fiber optic cables
Other lengths available
Path Length Application-dependent
Sample Conditioning Wobbe Index Sample Conditioning System
Wetted materials: SS316/316L, viton, PTFE, fused silica
Analyzer Calibration Factory calibrated, if possible
Human Machine Interface Industrial controller with touch-screen LCD display running ECLIPSE™ Software
Data Storage Solid State Drive
OPERATING CONDITIONS
Analyzer Environment Indoor/Outdoor (no shelter required)
Ambient Temperature Standard: -20 to 35 °C)
Optional: -40 to 60 °C
To avoid radiational heating, use of a sunshade is recommended for systems installed in direct sunlight.
Sample Temperature Standard: -40 to 66 °C
Sample Pressure 3600psig
UTILITIES
Voltage 85 to 264 VAC, single phase
Power Consumption 45 watts
Instrument Air 70psig
Nitrogen UHP calibration cylinder
OUTPUTS
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;
PHYSICAL SPECIFICATIONS
Select analyzer type: OMA-300 Wall-Mounted Analyzer
OMA-206P Portable Analyzer
OMA-406R Rackmount Analyzer

The following certifications are available.

NEC Class I, Division 1, Groups C & D; AEx d IIB T3
CEC Class I, Division 1, Groups C & D; AEx d IIB T3
ATEX ATEX Exp II 2(2) GD
GOST GOST Russian Gosstandart Pattern Approval

Resources

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