What is the function of "RATIO" on benchtop turbidimeters?

Document ID

Document ID TE991

Version

Version 2.0

Status

Status Published

Published Date

Published Date 27/05/2017
Question
What is the function of "RATIO" on benchtop turbidimeters?
Summary
RATIO function on benchtop turbidimeters.
Answer
The ratio function does several things; it compensates for color in the sample, light fluctuations of the lamp, haze and dust in the optics and it also serves to increase the stability of the turbidimetric readings.  When the ratio function is turned off, turbidity measurements are based off of the detector reading at 90° only.  With the ratio function turned on, the turbidity is determined by ratioing the nephelometric (90°) signal against a weighted sum of transmitted and forward scatter.  What this means is that with the ratio feature turned on, the reading takes into account forward scatter and transmitted light.  In samples less than 40 NTU, the difference between turbidity measurements with ratio on vs. off is negligible in most cases.  However, in higher turbidity samples, it is recommended that the ratio feature is always turned on as these differences become significant.

The TL2300, TL2350, and TL2360 have ratio modes. The TL2310 does not.