PAH Sensor for Oil in Water Measurement

Desun Uniwill PAH Sensor works in the measuring principle of UV fluorescence, it’s more sensitive and specific than the conventional infrared scattering or absorption methods. It can detect and measure polycyclic aromatic hydrocarbons (PAHs) from 0 to 1000 ppb (µg/L).

PAH probes connect to controllers for data display and recording. It features an RS-485 interface that allows easy and fast sensor configuration via Modbus.


Desun Uniwill is delighted to introduce its newly developed PAH Sensor to the market. The PAH Probe is a fluorimeter that accurately and continuously measures the concentration of Polycyclic Aromatic Hydrocarbons in water. These PAHs result from the incomplete combustion of petroleum and are present in most mineral oils or fuels. The sensor measures the sum of the PAHs passing in front of the lens, detecting and measuring polycyclic aromatic hydrocarbons (PAHs) from 0 to 1000 ppb (µg/L).

Desun Uniwill PAH Measurement Sensor operates on the principle of UV fluorescence, which is much more sensitive than the conventionally used infrared scattering or absorption method. This enables the determination of even the slightest traces of PAHs, for example, in drinking water and cooling water condensates. Application areas include the petrochemical industry, leakage detection in cooling and wastewater streams, as well as environmental monitoring. The Fluorescence PAH Oil Probe can be used stationary in shafts, flow, and pipelines. PAH probes connect to controllers for data display and recording. It features an RS-485 interface that allows easy and fast sensor configuration via Modbus.

Real-time PAH Sensor for Oil in Water Measurement

There are two measurement modes to choose from for you:

  1. PAH Probe mode, the probe is installed in the flow-through tank.
  2. PAH Analyzer mode combines the instrument with a flow-through tank to lead the liquid into the glass tube for measurement.

All of the above are real-time on-line measurement.

Technical Parameter

Product NamePAH SensorPAHs Analyzer
PrincipleFluorescence MethodFluorescence Method
0~500 ppb
0~1000 ppb
( Can be customized)
0~50 ppb
0~100 ppb
0~1000 ppb
( Can be customized)
Detection Limit5ppb0.5ppb
Response time<10s<10s
Minimum test intervals5s5s
InterfaceRS-485, Modbus RTURS-485, Modbus RTU
Power supply12-24VDC12-24VDC
Power consumption1.5W1.5W
Dimensions (L x Ø)
Protection LevelIp68Ip68
Storage temperature-20-80℃-20-80℃
working temperature0~ 50°C0~ 50°C
Inflow velocity0.1-10 m/s0.1-10 m/s

Measuring Principle

The measuring principle is based on the fluorescent properties of PAHs. Mineral oils rich in aromatic content will fluoresce when illuminated with ultraviolet light. The intensity of this fluorescence depends on the polyaromatic hydrocarbon (PAH) content of the oil. Typical oils that fluoresce include fuel oil, crude oil, hydraulic oil, and transformer oil. Each oil has its unique fluorescence intensity resulting from its specific PAH content. PAHs are integral parts of most mineral oil products and are a very specific indicator of oil contamination in water bodies and process water.

Marine ship Scrubber wash water PAH monitoring

After excitation caused by a UV light source, PAHs emit light with longer wavelengths after a short time delay. The intensity of this light is measured and is proportional to the concentration of the PAHs. This measuring principle is considerably more sensitive than absorption and scattered light measurement. It is possible to detect even the slightest trace of PAH contamination in water. Desun Uniwill PAH Sensor is a fiber-optic probe-based oil-in-water monitor. Fluorescence measurement assures continuous monitoring of oil and hydrocarbon contamination in water.

Features of PAH Oil-in-water Sensor

  • PAH Measurement Range: 0 – 1000 ppb (µg/L)
  • Equipped with an RS-485 interface that enables simple and quick sensor configuration via Modbus
  • In situ measurement, no sampling no reagents
  • Installations on the inlet and outlet of the scrubber
  • Fluorescence probe for PAH/Oil in water measurements
  • Corrosion-free Housing
  • Detects oil in water through UV fluorescence
  • Real-time in-line measurement
  • Simple installation and operation

Advantages of Desun Uniwill PAH Probe

  • Allowing for uninterrupted monitoring
  • High Sensitivity with Low Cost
  • Very High Accuracy
  • Compliant with current IMO regulations
  • Precisely measure hydrocarbons in water around oil wells
  • Continuous PAH oil-in-water monitoring for the right price
  • Minimal Maintenance
  • High Sensitivity and Selectivity
  • High Technology at a low price
  • Fast Response Time
  • Optical window with coating to minimize clogging

Demand Background of PAH Sensor

Exhaust emissions from ships’ engines using heavy fuel oils release gases and particulates that can harm human health and the environment. To mitigate this pollution, the IMO established regulations through the Marine Environment Protection Committee (MEPC). Ships are now required to decrease emissions of nitrogen dioxide (NOx), sulfur dioxide (SOX), and particulates. To comply with the 2020 sulfur limit of 0.5%, the shipping industry is implementing various strategies, such as installing Exhaust Gas Cleaning Systems (scrubbers) to neutralize sulfur. Any discharge into the environment must be monitored to ensure it doesn’t contain harmful substances. Ships must install monitoring systems and ensure they perform comprehensive regulatory analysis, as mandated by the IMO, including testing for PAH, pH, turbidity, and temperature. This ensures accurate and robust measurements are conducted in line with regulatory requirements.

measures the PAH concentration in the inlet and outlet of marine gas scrubbers (ECGS)

Now, Real-time detection may be possible with a new polycyclic aromatic hydrocarbon sensor (PAH), developed by Desun Uniwill. The fluorescence PAH sensor accurately measures the PAH concentration in the inlet and outlet of marine gas scrubbers (ECGS) offering all the benefits of the digital sensor technology. With PAH sensors, precise and real-time data is possible and can be monitored — and acted upon — by operators on ocean rigs.

PAH Testing Purpose

1. Trace oil in water
2. Leak detection
3. Oil Spill Monitoring
4. Water Quality Monitoring
5. Hydrocarbons monitoring in water
6. Oil in Water Monitoring

PAH Monitoring Medium

1. Ballast Water
2. Discharge Water
3. Industrial Wastewater
4. Drinking Water
5. Washing Water
6. Cooling water & condensate return
7. Process water (refineries, desalination plants)
8. Rainwater (airport runoff monitoring)

Application Areas of PAH Sensor

  • Monitoring drinking water resources
  • Biological wastewater treatment plant protection
  • Control of industrial discharges and wastewater
  • PAH measurement in processed water
  • Protection of membranes in desalination plants
  • Control of washing water from purifiers on ships
  • Marine ship Scrubber wash water monitoring
  • Pipeline monitoring
  • Bilge water monitoring
  • Outflow detection in cooling condensates
  • Environmental monitoring
  • Petrochemical
  • Wastewater monitoring
  • Fuel detection in natural waters and sewage plants
  • Gas Station/Refinery
  • Bottom Water Monitoring
  • Smoke Scrubbing
  • Desalination device
  • Airport Monitoring
  • Maritime EGCS (Scrubber)
  • Exhaust gas cleaning systems (EGCS) wash water monitoring
  • Supervision and online control of fresh water in waterworks and boreholes
  • Monitoring of wastewater in industrial and municipal sewage works
  • Crude oil detection, and leakage control at offshore oil pipelines
  • Exhaust gas wash water monitoring

Benefits of Using PAH Sensor

1, Early Detection and Prevention:

PAH sensors contribute to early detection and prevention of environmental pollution, allowing for proactive measures to mitigate potential damage. This leads to more effective pollution control strategies.

2, Cost-effective and Time-saving:

Compared to traditional lab-based analysis, PAH sensors offer a cost-effective and time-saving solution. Rapid data collection and analysis reduce operational costs and expedite decision-making processes.

3, Real-time Risk Assessment:

The real-time capabilities of PAH sensors enable immediate risk assessment. This empowers decision-makers to respond promptly to emerging environmental threats and implement targeted interventions.

4, Regulatory Compliance and Environmental Protection:

Employing PAH sensors supports regulatory compliance, ensuring that industries adhere to environmental standards. This, in turn, contributes to broader environmental protection efforts, fostering sustainable practices.

For any interests, freely contact for a quote.

FAQ About PAH Sensor

1. What is a PAH sensor?

A PAH sensor, which stands for Polycyclic Aromatic Hydrocarbon sensor, is a device used to detect the presence and concentration of polycyclic aromatic hydrocarbons in a given environment. Polycyclic aromatic hydrocarbons (PAHs) are organic compounds composed of multiple fused aromatic rings, and they are often found as pollutants in the environment due to incomplete combustion of organic materials such as coal, oil, gas, and wood. PAH sensors typically utilize various detection techniques such as spectroscopy, chromatography, or electrochemical methods to quantify PAH levels. These sensors are important tools in environmental monitoring, particularly in assessing air and water quality, as PAHs are known to be carcinogenic and can have harmful effects on both human health and the environment.

2. Why monitor PAH as a proxy for oil?

The EGCS Guidelines don’t request monitoring of PAH content specifically; rather, they focus on oil. However, the challenge lies in monitoring oil content well below 15 ppm continuously. Traditional oil-in-water sensors didn’t seem promising. Hence, an alternative approach emerged: using PAH sensors. These sensors can detect very low “oil” content, leveraging the presence of PAH compounds in oil.

3. Why monitor PAH in wash water?

Exhaust emissions from ships’ engines using heavy fuel oils release gases and particulates that can be detrimental to human health and the environment. In response, the IMO, through the Marine Environment Protection Committee (MEPC), established regulations to mitigate this pollution. Ships are now required to reduce nitrogen dioxide (NOX), sulfur dioxide (SOX), and particulate emissions. To comply with the 2020 sulfur limit of 0.5%, the shipping industry is adopting strategies, including installing Exhaust Gas Cleaning Systems (scrubbers) to neutralize sulfur. However, any discharge into the environment must be monitored to ensure nothing harmful is released. Therefore, ships need to install monitoring systems and ensure they perform the full regulatory analysis mandated by the IMO. This includes monitoring parameters such as PAH, pH, turbidity, and temperature to ensure robust and accurate measurements are made by regulatory requirements.

4. What are PAHs?

Polycyclic aromatic hydrocarbons (PAHs) constitute a large group of organic compounds with two or more fused aromatic rings. They occur naturally in petroleum and are also produced as by-products of fuel combustion.

PAHs represent an important class of environmental contaminants that are known to accumulate in ecosystems. The US EPA has identified 16 PAH compounds as priority pollutants. Some of these compounds are carcinogenic and/or mutagenic to mammals. Moreover, they exhibit both acute toxicity and sub-lethal effects on certain aquatic organisms. PAHs may also bio-accumulate in edible shellfish, providing a pathway to humans.

One source of PAHs is the incomplete combustion of fuel oils. Although engines and boilers are designed to optimize fuel combustion, exhaust gases inevitably contain a proportion of incompletely combusted material. This results in gaseous hydrocarbon and particulate emissions ranging from methane to very large complex molecules, including polycyclic aromatic hydrocarbons. While low molecular weight PAHs are primarily found unbound in the gaseous phase of the exhaust stream, heavier molecular weight PAHs constitute a group of substances that bind onto soot created during combustion.

5. How do you measure PAH in water?

Gas Chromatography-Mass Spectrometry (GC-MS):
This is one of the most widely used techniques for PAH analysis. GC separates the different PAH compounds based on their chemical properties, and MS detects and quantifies them based on their mass-to-charge ratio.

High-Performance Liquid Chromatography (HPLC):
HPLC can also be used for PAH analysis, especially when coupled with fluorescence or UV-visible detection methods. HPLC separates PAH compounds based on their affinity for the stationary phase.

Liquid Chromatography-Mass Spectrometry (LC-MS):
LC-MS combines the separation power of liquid chromatography with the detection capabilities of mass spectrometry. It can be effective for analyzing PAHs in complex matrices.

Thin-Layer Chromatography (TLC):
Although less commonly used for quantitative analysis, TLC can be used for qualitative screening of PAHs in water samples.

Related Video

Related Products

Online PAHs (Polycyclic Aromatic Hydrocarbons) Analyzer

Oil In Water Sensor

Related Blogs

Why do exhaust gas cleaning systems (EGCS) need a PAH measurement sensor?

Detecting and Measuring Polycyclic Aromatic Hydrocarbons (PAHs) with Fluorescence Sensors

Air Pollution PAH Detection Probe: Enhancing Exhaust Gas Cleaning System (EGCS) Efficiency

PAH sensors can be employed in marine scrubber systems(MS-SOx) for several purposes 

Measuring the Concentration of Polycyclic Aromatic Hydrocarbons (PAH) in Water

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