User Guide

Instruction Manual CON 510

13 NOTE: CONDUCTIVITY AND TDS SOLUTIONS HAVE ±1% ACCURACY AT

25°C ADDENDUM 1: CALIBRATION TIPS

You only need one calibration for measurement throughout the entire range of the meter. If a range was not calibrated,

the meter automatically detects the closest range calibrated and uses that calibration information. However, only the

ranges that were calibrated have maximum accuracy.

If you are measuring in ranges near to or greater than 20 mS (10 ppt), or near to or lower than 100 µS (50

ppm), calibrate the meter at least once a week to get specified ±1% F.S. accuracy.

If you are measuring in the mid-ranges and you washed the probe in deionized water and stored it dry,

calibrate the meter at least once a month.

Wet the probe for 10 minutes before calibrating or taking readings to saturate the probe surface and minimize drift. If you

make measurements at extreme temperatures, calibrate the meter at least once a week.

You should only use the conductivity/TDS probe specified for the meter. This probe has a built-in temperature sensor. If

you use a different probe without a temperature sensor, you must measure the solution temperature separately and

manually enter the solution temperature (see manual temperature compensation section).

14 ADDENDUM 2: CALCULATING TDS CONVERSION FACTORS

You can calibrate your meter using TDS calibration standard solutions. The calibration standard only needs to give the

TDS value at a standard temperature such as 25 °C. To determine the conductivity-to-TDS conversion factor use the

following formula:

Factor = Actual TDS ÷ Actual Conductivity @ 25 °C

Definitions:

Actual TDS: Value from the solution bottle label or as a standard you make using high purity water and

precisely weighed salts.

Actual Conductivity: Value measured using a properly calibrated Conductivity/Temperature meter.

Both the Actual TDS and the Actual Conductivity values must be in the same magnitude of units. For example, if the TDS

value is in ppm the conductivity value must be in µS; if the TDS value is in ppt the conductivity value must be in mS.

Check your factor by multiplying the conductivity reading by the factor in the above formula. The result should be in TDS

value.