UV254 Analyser – UV254Sense Probe
The UV254Sense UVA/UVT probe offers real-time analysis of organic UVA (ultraviolet absorbance) and UVT (ultraviolet transmission) in water.
Thanks to advancements in spectral analysis technology, monitoring organic contaminants in water has become far simpler than traditional lab based methods with the UV254 Probe. This probe, which comes standard with UV transmittance and UV absorbance outputs, continuously passes a small flow of water through a gap in the probe. The UV254 Probe shines UV254 light through the water and measures how much light is absorbed (UVA) and how much is transmitted (UVT).
By measuring the light absorbed at a specific wavelength (254nm), you can determine the concentration of contaminants, including organic compounds that contribute to the formation of disinfection by-products (DBPs). The UV254 sensor’s ability to detect the absorption of light provides insight into the amount of aromatic (or reactive) organic matter in water. This makes it a highly effective surrogate for monitoring total organic carbon (TOC) during organic removal processes.
Pi’s UV254 analyzers are capable of detecting natural organic matter (NOM), which is present in all water sources. The UV254 absorption tends to favor aromatic compounds, offering valuable benefits when monitoring the potential for DBP formation.
The UV254Sense Probe from Pi features a high-quality, long-lasting 254nm wavelength UV LED light source. This light passes through a sapphire window and shines into the water. A photodiode detector captures the light. The amount of light absorbed by the water is measured as UVA (ultraviolet absorbance), while the amount of UV light that passes through is recorded as UVT (ultraviolet transmission). The relationship between these two measurements follows Beer-Lambert’s law.
Cost of Ownership
The UV254Sense Probe is very cost-effective to calibrate and maintain, as it has no reagents or moving parts. Maintenance is simple, requiring only periodic cleaning and occasional “zeroing” of the analyzer with DI or RO water. With the option of automatic cleaning systems, maintenance costs are kept to a minimum. Combined with its low purchase price, the total cost of ownership for the UV254Sense Probe is significantly lower compared to other UV254 instruments.
Key Benefits
- UVA (ultra-violet absorbance) is an excellent surrogate parameter for TOC, DOC, COD and color.
- UVT (ultra-violet transmission) allows for the calculation of optimal UV dose for disinfection systems, improving efficiency.
- Accurate detection without the cost of reagents
- Few ongoing service or maintenance requirements – no moving parts
- Allows feed forward optimisation of coagulant control, This results in reduced chemical consumption, lower sludge removal costs, and minimized potential for DBP formation.
- Strong ROI with pay back on the analyser being seen by many customers within a few months.
- UVA measurement ensures performance of various contaminant removal technologies such as membranes (RO, NF, UF), ion exchange (nitrates and TOC removal) and granular activated carbon (GAC).
- Real-time UVA analyzers offer a final check of effluent water quality and can alert an operator in case of non-compliance.
- A UVA monitor can monitor the percentage removal of organics across any treatment system.
- Can be combined with a CRONOS® or CRIUS®4.0 for a multi-parameter UV254 analyser solution that suits your needs.
Standard Features
- Online continuous operation
- 254nm wavelength UV LED light source
- Displays UV transmittance or absorbance values
Optional Features
- Self-cleaning
- Process Controls
- Displays UV transmittance or absorbance values
- UVT (ultra-violet transmission) – The primary application of UV transmission monitoring is to regulate the intensity of UV light output in UV disinfection processes.
- UVA (ultra-violet absorbance) – The primary application of UV absorbance monitoring is to optimize water treatment processes, such as by controlling coagulant dosing or providing a surrogate measurement for parameters like TOC or COD.
- Process control – Direct measurement of a parameter to control a process such as coagulation, UV disinfection and membranes.
- Specific parameter correlation – Correlated to another parameter that is impractical or expensive to measure in real time such as TOC, BOD and COD.
- Event monitoring – Used to monitor baseline absorbance which can trigger an alarm when an absorbance event occurs, such as security monitoring for contamination events in a municipal installation.
- Industrial water and wastewater secondary and effluent monitoring – To determine treatment efficiency after secondary treatment and provide tertiary treatment monitoring and control.
- Automatic cleaning system
- Multiple sensors on a single analyser
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>> Correlating the UV254 Water Quality Parameter to Other Organics Parameters
By shining light at a specific wavelength (254nm) through water, you can measure how much of the light is absorbed by contaminants. These contaminants may include particulate matter or organic substances that absorb light at that wavelength.
There are two main ways to use this:
The first is by measuring UV light transmission (ultraviolet transmittance). This is crucial for determining the strength of UV light used in disinfection.
The second is by measuring UV absorption (UVA). This indicates the level of organics in the water and can serve as a surrogate for parameters like TOC, DOC, and COD. It is most commonly used in coagulation control at water treatment facilities.
UVA = 2-log10UVT
UVA and UVT are essentially the same measurement expressed in different ways
Coloured raw water is often caused by organics, so both UV and color measurements can provide similar insights. While color monitors are useful for assessing the appearance of drinking water, many organics do not reflect in the visible spectrum (meaning they have no color), and other factors, such as manganese, can also cause color in water. UV254 measurement is more sensitive to aromatic compounds in the water, which can react with chlorine to form unwanted disinfection by-products (DBPs). As a result, UV254 is typically considered a more valuable measurement than color, especially for coagulation control.
Pi removes interfering particulate using a self-flushing filter.
Total Organic Carbon (TOC) is a challenging and costly parameter to measure online, and UV254 can often be used as a surrogate measurement. To do this, the user must first establish a correlation between TOC and UV254 offline and then input this relationship into the analyzer. The analyzer can then output TOC values by correlating the UV254 reading to the TOC.
The accuracy of this correlation depends on the composition of the TOC. If the TOC is made up entirely of UV254-absorbing organics, the correlation will be excellent. However, if the TOC contains non-absorbing organics, the correlation will weaken predictably, reaching zero when the TOC consists entirely of non-absorbing organics. In general, municipal water and wastewater typically show very good correlations.
The UV254Sense Probe can accommodate path lengths of 2, 5, 10 or 20mm.
By flushing regularly and automatically (controlled by the analyser) with clean water
Typically, the bulb lasts 10 years
Yes, as long as the sensor isn’t in the path of stray UV light (e.g. sunshine)
Yes! Our controllers can handle up to 16 sensor inputs. Please contact Pi for details
Document | Type | Size |
---|---|---|
UV254Sense Probe | Brochure | 486kB |
UV254Sense – Water | Brochure | 652kB |
UV254 Sample Strainer Unit | Technical Note | 655kB |
Laboratory Based and Portable Analysers | Brochure | 636kB |
Correlating the UV254 Water Quality Parameters to Other Organics Parameters | Technical Note | 666kB |
Importance of Measuring UV Transmittance (UVT) for UV Disinfection | Technical Note | 445kB |
Benefits of UV Transmittance (UVT) Field Testing for Selling and Servicing UV Disinfection Systems | Technical Note | 459kB |
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