How do I know when something is wrong with my conductivity measuring cell?

The conductivity of the deionized water should not exceed 20 µS/cm. If the value measured at the start of the measurement is higher than this, it is indicative of a problem with the conductivity measuring cell. This is generally caused by the electrode being contaminated with sample residue. To avoid this, the measuring vessel and the conductivity measuring cell should be cleaned thoroughly after each determination (see Cleaning after the determination ).

Does the volume of the measuring solution play a role when determining the induction time?

The exact volume of the measuring solution is less significant when determining the induction time, as only the relative change in conductivity is evaluated.

Do I need to determine the cell constant of my conductivity measuring cell?

The cell constant of the conductivity measuring cell used in the Rancimat lies between 1.0 and 1.2 cm-1. For measurements in which the induction time is to be determined, more precise calibration is not required, as only the relative change in conductivity is evaluated in the case of the induction time. If, however, the stability time is to be determined, in which the absolute change in conductivity is evaluated, we recommend that you determine the cell constants. You can find more detailed information on working with calibrated conductivity measuring cells and determining the cell constants in the manuals for your instrument and the software used.

Does the position of the PTFE tubing in the measuring vessel play a role?

You must ensure that the PTFE tubing does not feed the air directly onto the conductivity measuring cell. If gas bubbles are released onto the electrode, then this results in noisy measurement curves. PTFE tubing position OK: PTFE tubing position not OK:

Klargøring af målebeholderen

Tilbage til overblik

support-and-service/stab-how-to-operate-measuring-vessel/_1

Hæld måleopløsningen i målebeholderen (6.1428.030, 6.1428.100) og fastgør målebeholderens dæksel med integreret ledningsevnemålecelle (6.0913.130).
Deioniseret vand bruges som måleopløsning. Ultrarent vand er ikke påkrævet. Konduktiviteten ved starten af målingen bør ikke overstige 20 µS/cm.
Ved montering af PTFE-kanylen (6.1819.080 + 6.1808.050) i målebeholderens dæksel, skal du sikre dig, at luften ikke tilføres konduktivitetsmålecellen ved den senere måling. Hvis der frigives gasbobler på elektroden, vil målekurverne være støjende.