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OiW-100 Oil in Water Analyzer main view

Oil-in-Water Analyzer

Continuously monitoring dynamic oil concentrations in effluent water, the OiW-100 is a painless and economical option for complying with increasingly stringent wastewater regulations.

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  • Precise Oil-to-Aromatics Correlation
    Straightforward UV-Vis analysis
  • 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


  • Unattended operation
    Stabilized by Auto-Zero; remote operation optional
  • Inherently safe design
    Sample 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/reagents
    Solid state design
  • 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


Specific use cases for the OiW-100 include:

  • wastewater
  • pond water
  • cooling water

The suitability conditions for the OiW-100 Oil-in-Water Analyzer include:

  1. The sample must be a homogenous mixture (uniform distribution) of oil and water. Due to the immiscibility of oil in water at higher concentrations, the maximum practical concentration range is typically 0-100 mg/L.
  2. The oil must be defined and contain UV-absorbing constituent chemicals (aromatic hydrocarbons). The analyzer measures the UV absorbance of these constituent chemicals and correlates it to the total oil concentration, so the oil composition must be consistent.
  3. The water can not contain additional UV-absorbing chemicals which are not considered oil constituents. These chemicals will interfere with the analysis and produce false-positive oil concentration. This limitation makes the OiW-100 unsuitable for some wastewater applications where water composition is unpredictable.


Principle of Operation

To analyze the chemical composition of the sample, the OiW-100 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.

Spectrophotometer Principle of Operation

The OiW-100 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

Oil-to-Aromatics Correlation

To measure total oil concentration in water, the OiW-100 measures the total absorbance of aromatic hydrocarbons in the water and correlates this value to total oil. This method requires calibration using a sample of the customer's oil to establish a highly accurate oil-to-aromatics correlation. Of course, this method also requires that the oil contain aromatics (e.g. benzene) because these are the primary UV-absorbing species in the oil.

The height of the total aromatics' absorbance curve correlates directly to the real-time oil concentration:

Absorbance Curves: Oil Analytes

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


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 Factory calibrated with customer sample; 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)
Using immersion probe: 100 bar (1470 psig)
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;
Size Analyzer: 24" H x 20" W x 8" D (610 x 508 x 203 mm)
Weight Analyzer: 32 lbs. (15 kg)
Enclosure Standard: wall-mounted carbon steel NEMA 4 enclosure
Accuracy 0-20 mg/L range: ±2% full scale
0-100 mg/L range: ±2% full scale
Response Time 1-5 seconds
Zero Drift ±0.1% after 1hr warm-up, measured over 24hrs (constant ambient temperature)
Sensitivity ±0.1% full scale
Noise 0.004 AU at 220nm
Standard Design General Purpose
Available Options ATEX, IECEx, EAC
Please inquire with your sales representative for additional certifications (CSA, FM etc.).


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