Tethys Instruments SAS

- Model UV500 - Online Water Analyzer



The UV500 is a on-line water analyser based on a high resolution UV-visible spectrograph. It allows to monitor simultaneously many different parameters for waste water treatment plants or river monitoring stations with an excellent stability and low operating cost. The same spectrograph can measure organic matter, nitrate, colour, turbidity, phosphate, ammonia and hydrogen sulphide. A complementary UV-visible fluorescence module allows the measurement of aromatics hydrocarbons (PAH). Nephelometric turbidity by visible or infra-red laser diode is also available. The full UV-visible spectrum can also be used to monitor specific chemical process making the UV500 a ideal instrument for chemical plants.

External probes can be added for physicochemical parameters like pH, ORP, dissolved oxygen, conductivity and turbidity. Thanks to its automatic cleaning system and its extremely long life time lamp, the maintenance is roughly limited to the periodic refill of the inexpensive cleaning solution and eventually reagents depending on the parameters.

UV-Visible Spectroscopy on Liquid and Gas Phase: A Unique Method

A 2048 pixels high resolution spectrograph scanning wavelengths from 180 nm to 750 nm is the master part of the UV500. Direct absorbance measurement for UV254, COD, BOD, TOC, NO3, Colour PO4 and Cr VI brings fast and stable measurements with a simple hydraulic circuit. Factory predefined or local multi-point calibration allows to get readings of COD, BOD and TOC under the UV alternative method for compatible applications. UV spectroscopy brings faster results than conventional methods like COD, BOD, TOC with much less maintenance once the correlation is dertermined.

An additional circuit allows the measurement of ammonia and hydrogen sulphide on the gas phase after a stripping step. This unique method allows measurements on extremely turbid or coloured samples like activated sludge as the gas phase is not affected. A fast Fourier transform (FFT) brings an exceptional selectivity and no interference has never been reported after years of operation on many different applications.

The patented flow cell allows very high level of suspended solid without clogging. The turbidity is automatically compensated by a dual-wavelength method.

The UV source is a xenon flash lamp specified for 109 flashes that corresponds to more than 10 years of life time with one measurement every minute.

Physico-chemical measurements like pH, ORP, dissolved oxygen, conductivity can be added to the internal measurements by using external probes. The dissolved oxygen probe is based on fluorescence method for a lower maintenance and higher stability.

Measuring principle by absorbance (liquid and gas phase)

1 : spectrograph,
2 : beam splitter,
3 : patented water flow cell,
4&5 : xenon lamps,
6 : gas flow cell ,
7 : gas pump,
8 : stripping pot,
9 : temperature probe

UV fluorescence principle

1 : Xenon lamp,
2 : excitation filter,
3 : flow cell,
4 : emission filter,
5 : photomultiplier,
6 : reference photo detector

Laser Diode Turbidity Principal (Nephelometric)

1 : Laser diode (650 nm or 850 nm),
2 : flow cell,
3 : Photo detector

Patented Flow cell

1 : Allows very high level of suspended solid without clogging for all the optical measurements making it suitable for industrial & municipal waste water application. More...

The colour touch screen and intuitive interface available in 9 different languages (Chinese, English, French, German, Hungarian, Italian, Portuguese, Spanish, Turkish) makes very easy to test or configure the analyser. Many test functions allows to test and troubleshoot each element of the analysers (light signal, pumps, solenoid valves, etc...) to setup quickly a maintenance diagnostic. An acid resistant protection film on the screen assumes an efficient long term protection.


The RS232 port supports the MODBUS protocol to transmit each Standard channel value to a SCADA system. Additional parameters are available like status code, error code, calibration values and pumps run time. Basic 4-20 mA output modules can be plugged on the main board for each Standard channel, in the limit of 12 modules. A USB port enables to download on any USB key the last 5000 recorded measurements as well as a diagnostic file containing the configuration and useful information for remote troubleshooting.The recorded measurements file can be imported to Excel for graphs or other treatments. The software of the analyser can be upgraded by connecting a USB key. A USB port enables to download on any USB key the last 5000 recorded measurements as well as a diagnostic file containing the configuration and useful information for remote troubleshooting.The recorded measurements file can be imported to Excel for graphs or other treatments. The software of the analyser can be upgraded by connecting a USB key.


When different streams need to be analysed, for example inlet and outlet of a plant, an optional multiplexing system delivers relay contacts to control external electric-valves or external pumps.

Up to 6 different streams can be selected

The Standard channels can be either duplicated (each one having its own 4-20mA output or MODBUS register), or measured sequentially to fit with the maximum of 16 Standard channels (a MODBUS register tells which stream is currently being measured).

The UV500 can adapt to many different kind of sampling depending of the application : surface water, drinking water, process water or wastewater.

If the water is already pressurized, the sample can be admitted directly inside the analyser with a maximal pressure of 4 bars. Otherwise an optional built-in peristaltic pump, synchronised with the measurement to extend the tubing life time, allows to take the sample directly from a tank located up to 6 meters below the analyser. For demanding applications with long distances, another peristaltic pump in a separate enclosure is proposed as an option. For some applications on river water or wastewater where two sampling pumps are necessary, the UV500 delivers a relay contact to synchronise the primary pump. The delay and running time of each pump can be adjusted easily in the parameters menu of the analyser.

  • Sample flow:
    • Recommended: 0 - 5 l/min
    • 0 - 0.5 l/min for NH4 or H2S
  • Sample pressure:
    • 0 - 4 Bar (0 - 1 Bar with sampling peristaltic pump)
    • 0 - 0.5 Bar for NH4 or H2S
  • Sample temperature:
    • 0 - 80 °C
    • 0 - 30 °C for NH4 or H2S
  • Wet parts materials: Quartz, Polypropylene, Polyethylene, FPM (viton), PMMA (+ Pharmed and glass for NH4 or H2S)
  • Measuring time: 5 sec (except PO4, NH4, H2S : 3 min)
  • Measurement interval:
    • 1 min to 720 min
    • Memory: 5000 lines of measurements (up to 16 channels) with date and time
  • Consumption:
    • Cleaning solution (5% sulfuric acid): 220 ml/day
    • Reagent for PO4: 2 ml per measurement
    • NaOH 10% for NH4: 2 ml per measurement
    • HCl 10% for H2S: 2 ml per measurement
  • Maintenance interval: Recommended: 6 months to 1 year (except for refilling)
  • Power supply: 90 - 264 VAC 50/60 Hz 80 VA
  • Screen: Colour TFT LCD 640x480 pixels with LED backlight
  • Communication:
    • RS232 with MODBUS protocol
    • RS485 for external probes (DO, TSS)
    • USB
    • WI-FI (IEEE802.11B) optional
    • Ethernet (IEEE802.3) optional
  • Certifications: CE, EN 61010-1, EN 61326
  • Enclosure: Stainless steel with epoxy coating, IP65, wall mounting brackets
  • Dimensions: 525x345x260 mm
  • Weight: 20 to 30 kg depending on the configuration

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