Instruction manual

4 Measurement
28
 What is TDS?
The term TDS is an acronym for “Total Dissolved Solids”, representing the total amount of
solids dissolved in a solution.
The conductivity of a solution is determined based on the amount of salinity, minerals, and
dissolved gasses in it. In this respect, conductivity is the indicator of total amount of all
substances in the solution. TDS indicates only the amount of dissolved solids in the solution
among others.
Although you can obtain accurate results using TDS for comparing materials made up of a
single component such as NaCl, errors greatly vary when comparing different kinds of
solutions.
The relationship between conductivity and TDS is shown in the equation below:
 Number of moving averages (dumping factor)
Set the number of moving averages for measurements to be displayed.
1. Open the measurement condition setting screen referring to “ How to open basic
setup menus” (page 19).
The setup item selection screen is displayed on the measurement display, showing the
display for unit setting, “Unit”.
2. Display “dFct” on the measurement display using the DOWN key, and press the
ENT key.
The sub-display starts blinking. Now you can change the setting.
3. Press the UP/DOWN key to set the TDS conversion coefficient.
UP key : Increments the value by 1.
DOWN key : Decrements the value by 1.
The setting range is 1 time to 20 times.
4. Press the ENT key to establish the setting.
Tip
z To set another item in the measurement condition setting next, press the UP key to display it.
z To return to the basic setup menu, press the MEAS key.
Conductivity in SI unit (mS/m)
TDS (mg/L) ＝ L (mS/m)
× K × 10
Conductivity in conventional unit
(
µS/m)
TDS (mg/L) ＝ L (µS/cm)
× K
K = TDS conversion coefficient
L = Conductivity