A Pyxis ST-500’s optics read fouled, so its PTSA and turbidity readings may be low.
| At a glance | |
|---|---|
| Code | 340 |
| Shown as | Probe Needs Cleaning |
| In the alarm list | The device’s name, then Needs Cleaning — for example Tower PTSA Needs Cleaning (upcoming firmware) |
| Severity | Warning |
| Category | 3xx — Process / sensor signals |
| Clears | Automatically, when the probe reads clean again — or when the probe is removed |
New in an upcoming firmware update. Earlier firmware does not raise this alarm.
The ST-500 rates the cleanliness of its own optics as a count. The controller reads it every 30 seconds. Three readings in a row above 3000 mean the probe is fouled. The alarm names the probe, and its message gives the count, for example Cleanliness reads 3480 (fouled above 3000). The probe’s page shows Fouled next to the turbidity.
The alarm clears after three readings in a row below 2700. The gap stops a probe near the limit from raising and clearing the alarm over and over.
Records the alarm and marks the probe Fouled. It does not stop the control modes that use the probe.
A fouled probe reads low, so a PTSA mode feeds more to make up. Clean the probe promptly. Until then, watch the feed and the tower’s actual product level.
If the alarm comes back soon after cleaning, the water is fouling the probe faster than usual. Clean it more often, and check the sample line for iron, oil, or biofilm.