Sensor Reaction Time (T90) for Double Gold Sensors – ZIRKON® DIS and ZIRKON® ONE DIS – Kuntze Instruments GmbH

What is T90 (Reaction Time)?

The reaction time of a measurement is the time needed for the sensor to respond to a sudden, abrupt change in concentration.

T90 is the standard way to specify this: it is the time required to reach 90% of the concentration change.

Example: If the concentration steps from 0 mg/L to 1 mg/L free chlorine, T90 is the time until the sensor reading reaches 0.9 mg/L. The smaller T90, the faster the sensor follows real changes in the water.

Why T90 Matters

In disinfection control, fast reaction times help with:

Process control – quicker response to dosing or concentration changes
Safety – faster detection of under- or over-dosing
Compliance – many specifications refer to T90 or similar response criteria

Kuntze Double Gold (amperometric) sensors are used in the KRYPTON® K and KRYPTON® ONE systems for free chlorine, chlorine dioxide, and ozone. Their T90 values have been determined in independent tests at the IWW Water Centre (Mülheim an der Ruhr, Germany).

T90 Values – IWW Test Results

The following table summarizes T90 reaction times from IWW testing for Kuntze systems using Double Gold type sensors (ZIRKON® DIS and ZIRKON® ONE DIS).

System	Sensor	Parameter	T90	Source / Note
KRYPTON® K (DIS / Multi)	ZIRKON® DIS	Free chlorine	21 s	IWW – Chlormessung mit Krypton K
KRYPTON® ONE	ZIRKON® ONE DIS	Free chlorine	24 s	IWW test report Dec 2025 – for both positive and negative concentration changes

Systems and Sensors Covered

KRYPTON® K – Includes KRYPTON® DIS and KRYPTON® Multi; both use the ZIRKON® DIS sensor for free chlorine (and chlorine dioxide / ozone where applicable). T90 for a concentration change in chlorine in a Kuntze Krypton system was determined to be 21 s.
KRYPTON® ONE – Uses the ZIRKON® ONE DIS sensor on the NEON® ONE platform. The response time (T90) for free chlorine was 24 seconds for both positive and negative concentration changes (IWW, 18 December 2025).

References

IWW – Chlormessung mit Krypton K (Prüfbericht / Kurzbericht), 2008
IWW – Kuntze Instruments – Neon One free chlorine, 18 December 2025 (test report and brief report)