7
PRINCIPLE OF OPERA
TION
3. PRINCIPLE OF OPERATION
HI93703-11
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.
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 SiO2). For your reference the conversion table between
these measurement units is shown below:
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
* 1 FTU = 1 NTU
