TriOS

TriOS LISA-254 SAC254 Sensor

TriOS LISA-254 is a UV-LED immersion sensor that measures SAC254 and, through application-specific correlation, COD, BOD and TOC equivalents, with turbidity compensation at 530 nm.

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Technical specifications

TriOS LISA sensor: a stainless steel cylindrical body with a black TriOS label, an open sensing head at one end and a cable at the other

Measurement technology	2 LED light sources (254 nm and 530 nm); photodiode detector
Measuring principle	Optical attenuation and transmission
Optical path lengths	0.3 / 1 / 2 / 5 / 10 / 20 / 50 / 100 mm, selected with adapter pieces according to the application
Measured parameters	SAC254, COD (CODeq), BOD (BODeq), TOC (TOCeq)
Measuring range (depends on optical path)	SAC254 0.05-1500 1/m · CODeq 0.08-2200 mg/L · BODeq 0.025-700 mg/L · TOCeq 0.03-880 mg/L · turbidity (530 nm) 0.2-4000 FAU. Upper limits apply to 1 mm and lower limits to 100 mm optical path (laboratory conditions); COD, BOD and TOC use an application-specific correlation
Turbidity compensation	Automatic, with a second measuring channel at 530 nm
Repeatability	0.2 %
Response time	T100: 4 s
Housing material	Stainless steel (1.4571 / 1.4404) or titanium (3.7035)
Weight	Approx. 2.3 kg stainless steel, 2.1 kg titanium (with 10 mm optical path)
Pressure rating	30 bar with SubConn connector; 3 bar with fixed cable; 1 bar in a FlowCell (2-4 L/min)
Protection class	IP68
Operating and sample temperature	+2...+40 °C for the specified measurement accuracy
Interfaces and communication	Ethernet TCP/IP; RS-232 / RS-485 (Modbus RTU) or 4-20 mA analog
Power supply and consumption	12-24 VDC (± 10 %), ≤ 1 W
Internal data logger	Approx. 2 MB
Maintenance and calibration	Typically ≤ 0.5 h/month; calibration and maintenance interval 24 months

TriOS LISA-254 is an immersion sensor that monitors the organic content of water and wastewater continuously and without reagents, through ultraviolet absorption at 254 nm (SAC254). It uses UV-LED technology with a second LED at 530 nm for turbidity compensation, draws no more than 1 W and has a T100 response time of 4 s. Mikron Proses (Üsküdar, Istanbul), TriOS’s solution partner in Turkey, provides application consulting on sensor selection, commissioning and calibration.

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Two wavelengths and turbidity compensation

In addition to the 254 nm UV measuring channel, LISA-254 has a second LED at 530 nm. This reference channel detects the light scattering caused by turbidity and compensates the SAC254 value automatically. Without sampling, sample preparation or reagents, the sensor reports:

SAC254: absorption at 254 nm as an indicator of organic load.
COD (CODeq), BOD (BODeq) and TOC (TOCeq) equivalents: the sensor can be configured with an application-specific correlation for the direct output of these parameters.

Optical paths and robust construction

The optical path length is adapted to the application with adapter pieces: 0.3, 1, 2, 5, 10, 20, 50 or 100 mm. The measuring range depends on the optical path.

Housing: stainless steel (1.4571 / 1.4404) or titanium (3.7035); the manufacturer names the titanium version for very harsh environments such as high chlorine concentrations.
Pressure: up to 30 bar with the SubConn underwater connector, 3 bar with a fixed cable and 1 bar in a FlowCell.
Fouling protection: the optical windows are nano-coated, and a compressed air purge such as the TriOS AirShot system can be used for cleaning.

Interfaces and integration

LISA-254 is configured with a standard web browser through the TriOS G2 interface. It can be connected to existing process control systems or external data loggers through Ethernet (TCP/IP), RS-232 / RS-485 (Modbus RTU) or a 4-20 mA analog output, and an internal data logger of about 2 MB stores measured values. For a bypass installation with ultrasonic window cleaning, see the FlowCell FC 48/10 USC.

For a full-spectrum alternative that also measures nitrate and nitrite, see the TriOS OPUS spectral sensor. For selection background, see the spectral water quality sensors guide, and for all analyzers online analyzers.

Applications

Monitoring of organic load at drinking water treatment plant inlets and in the network
Biological treatment and discharge monitoring in wastewater treatment plants

Datasheets and manuals

Documents were last compared with the manufacturer's source on 2026-09-25.

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