ZIRKON® ONE DIS / Zirkon® DIS Sensors: No raw signal - what to do? – Kuntze Instruments GmbH

Overview

This article is a general troubleshooting guide when a ZIRKON® ONE DIS or ZIRKON® DIS chlorine sensor shows no usable raw value or the raw value does not change when chlorine is present. The same physics applies on NEON® ONE and on legacy Neon® / Krypton® analyzers; only the raw value on the display differs.

Where to read the raw value

Platform / analyzer	Raw value on the instrument
NEON® ONE (KRYPTON® ONE) with ZIRKON® ONE DIS	ppm-raw (mg/L-raw)
Neon® Multi, Krypton® Multi, Neon® DIS, Krypton® DIS (and related legacy DIS configurations)	mV (millivolts)

A “missing” signal means the raw stays at or near zero (0 mV on legacy, 0 ppm-raw on NEON® ONE) or remains flat while you change chlorine or move the sensor to water that should produce a clear response.

Typical symptoms

Legacy (mV): raw stays near 0 mV or does not increase when chlorine is present.
NEON® ONE (ppm-raw): raw stays near 0 or shows no meaningful change when conditions change.

Troubleshooting procedure

Reference measurement and sampling

Before focusing on the sensor alone, make sure any hand reference (for example DPD) is meaningful:

Take the sample at the sampling tap / sample valve on the flow cell (the intended sample point for the installation), not from an arbitrary line or vessel.
Use a trustworthy procedure (correct handling, fresh reagents, stable timing, representative flow).
The disinfectant in use must match the reference method (for example the right DPD chemistry or range for free chlorine, total chlorine, chlorine dioxide, etc.). If the reference does not match the process chemistry, the comparison to the analyzer will be misleading.

Measurement response test

The disinfectant in use must match the choosen sensor / measurement parameter.
Inspect the sensor: Look at the sensor first. Clean it even if the electrodes look clean — films are not always visible.
Manual cleaning: Remove the sensor and clean it manually (e.g. abrasive household cleaner such as Ajax / Comet, damp paper towel). Clean electrodes thoroughly, then rinse well.
Reinstall and polarize: Reinstall the sensor in the flow cell. Allow polarization (typically 15–30 minutes under normal flow), then read the raw value again before deciding the sensor is still “dead.”
Verification in a beaker: If the online raw value is still unclear, place the sensor in a beaker with water and stir continuously. ZIRKON® ONE DIS and ZIRKON® DIS sensors are amperometric: without movement at the measuring surface, the raw value may stay misleadingly low even if chlorine is present. A static or unstirred test is therefore not conclusive.
Interpreting raw values in the stirred beaker: Stirring removes the worst “no flow” effect at the electrode, but it is not the same as constant, controlled process flow. With chlorinated water and a sensor that is basically working, you should therefore see a clear increase in raw (mV or ppm-raw) compared to unchlorinated water — but you should not expect the beaker raw to match the exact concentration from a hand sample; use a proper reference and procedure for that.
Graduated checks (typical order):
- Application water only (stirred): raw should stay near zero and not drift strongly negative.
- Application water with the process disinfectant dosed as on site: raw should rise if the chemistry matches the sensor.
- If there is still no response, try tap / drinking water with the same disinfectant dosed in a controlled way. If the site uses an unusual biocide, you can also try a chemically equivalent alternative at a known dose to see whether the sensor responds at all.
If there is no response at all: After cleaning, reinstall/polarization, and the stirred checks above, if the raw value still does not move for any of the liquids, treat the measurement as failed and contact us(send documented test results for our reference).

Calibration note

If the raw value is still missing or meaningless, calibration will not give a trustworthy slope or concentration. Restore a proper raw response first, then calibrate with a good DPD reference. See also the related article on zero slope / meaningless readings after a bad calibration.