The automatic prism wash cycle consists of the following phases:
- Precondition
- Wash
- Recovery
The optional preconditioning function is used for example to blow out the condensate from the washing line before washing. After the preconditioning there is a 1‑s pause to avoid having both precondition and wash relays active at the same time.
The wash cycle is initiated when the wash interval has elapsed. The wash can also be started by configuring a general input for external wash, see Configuring general I/O module card, or manually from the user interface at . The order of priority for these wash triggers is:
- Manual wash
- External wash request
- Wash interval timer
The wash relay is closed for the wash time specified in the wash settings.
After the wash phase is completed, a recovery time is spent. During the wash cycle (precondition, wash, recovery) the measurement result is in hold unless otherwise specified.
Preventing automatic wash
The precondition and wash relays are never activated by the automatic wash control:
- If diagnostic message is NO SAMPLE as this indicates a clean prism in an empty process line. The diagnostic message is WASH STOP / NO SAMPLE.
- If a wash stop is present, indicating for example that there is no process flow. The diagnostic message is EXTERNAL WASH STOP.
- If the process temperature limit is activated and the temperature falls below the limit, indicating that the process is not running. The diagnostic message is LOW TEMP WASH STOP.
