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The ORAKEL Turbidity monitor automatically varies the light output so that the turbidity  can be measured independently of background light and electronic drift. It is ISO 7027 compliant and covers a range of 0.01-1000 NTU (0.01-2000mg/l depending on the sample).

The ORAKEL System determines true turbidity and/or suspended solids in water, using a nephelometric measurement of scattered light in accordance with ISO 7027. The sensor uses lifetime-based optical technology to provide an extremely stable, accurate, low maintenance sensor with no moving parts and no consumables.


Each probe is equipped with a light source, a side detector for the measurement of scattered light from the sample and a reference detector for monitoring the light output. The light source is a long-life IR LED emitter.

This configuration allows accurate and reliable measurements of turbidity and suspended solids to be made.

Reliable calibration can be carried out using a single calibration with no need for a ‘zero’.

The probes are constructed of stainless steel and sapphire so can withstand demanding operating environments. An autoclean system can be included to keep the optical surfaces clean, thereby reducing  maintenance to a potential ‘maintenance free’.


Calibration of the ORAKEL System really couldn’t be easier! Either take a reading of the water with another  method and enter the value into the analyser or put the sensor into our black polyethylene calibration pot filled with 0.5 litre of standard (typically 20 NTU).

The analyser calibrates the sensor by a procedure that reduces the light output through four stages, taking measurements at each.

This process provides a very accurate and reliable zero and span without the requirement to use a ‘0’ NTU sample.


Anywhere where the measurement range is 0.01-1000 NTU (approximately 0-2000 mg/l, application dependent) is a suitable application for this sensor.

This includes traditional monitoring applications such as those listed here.

■ Raw water inlet
■ Settled water turbidity
■ Final water turbidity
■ Wastewater effluent turbidity
■ Fire hydrant monitoring
■ Swimming pool clarity monitoring


Selectable within 0.01-1000 NTU, 0.01-2000 mg/l (application dependent).

Typical Ranges
0.01-20 NTU, 0.01-100 NTU, 0.01-1000 NTU.

r2 > 0.99.

Response Times
T90 ≥ 10s (adjustable based on averaging).

< 1% of measured value or 0.01 NTU (whichever is greater).

< 0.3% of measured value or 0.005 NTU (whichever is the greater) (Ref: ISO 15839).

Unit of Detection
0.01 NTU (0-10 NTU, Ref: ISO 15839).

-20 to +85°C.

0-10 bar.

10 seconds – 10 minutes.

Lamp Source
IR LED, 860nm.

Cleaning Cycles
User settable cleaning cycle time and cleaning time.

Autoclean water jet.

Enclosure Rating

Sensor Environmental Protection

Value, alarms and graphs at the same time.

0.001 NTU (0-10), 0.01 NTU (10-100), 0.1 NTU (>100).

One point (zero not required).

38mm (1.5 inch).

278mm (11 inch).