5
* 1 FTU = 1 NTU
HI 93703 has been designed to perform measurements according
to the ISO 7027 International Standard.
The instrument functions by passing a beam of infrared light
through a vial containing the sample being measured.
The light source is a High Emission Infrared LED with a wavelength
peaking at 890 nm, ensuring that the interference caused by
colored samples is minimum.
A sensor, positioned at 90° with respect to the direction of light,
detects the amount of light scattered by the undissolved particles
present in the sample. The microprocessor converts such readings
into FTU* values.
As noted above, FTU unit is equal to the NTU unit. However, there
are other known measurement units for turbidity: Jackson Turbidity
Unit (JTU) based on the old method of Jackson's candle, and Silica
Unit (mg/L of SiO
2
). For your reference the conversion table
between these measurement units is shown below:
PRINCIPLE OF OPERATION
JTU FTU/NTU SiO
2
(mg/L)
JTU 1 19 2.5
FTU/NTU 0.053 1 0.13
SiO
2
(mg/L) 0.4 7.5 1