K-Patents PR-23 - Manual (Page 60)

52 PR-23 instruction manual
from the user interface at the Sensor status display (see Section 5.1.3). The order of
priority for these wash triggers is:
1. manual wash
2. remote wash request
3. wash interval timer
WASH
RECOVERY
INTERVAL
PRECOND.
Figure 6.14 The automatic prism wash cycle
Note: For safety reasons two sensors never wash simultaneously. If the manual wash
button for sensor A is pressed while sensor B is washing, the wash cycle for sensor A
is started after B has finished. Similarly, if the interval time for sensor B elapses when
A is washing, the wash for sensor B is delayed until A has finished.
In case of remote wash request the request is discarded if it arrives when the other
sensor is washing. The request is honored only if the contacts are held closed until
the other sensor has finished.
The wash relay is closed for the wash time specified in the wash settings. If the wash
auto-cut functionality is active, the wash may be ended earlier (see Figure 6.16). The
specified wash time is never exceeded.
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 preconditioning and wash relays are never activated by the automatic wash con-
trol:
− Under the diagnostic message
NO SAMPLE (see Section 8.2.6) as this indicates a clean
prism in an empty process line. The diagnostic message is WASH STOP/NO SAMPLE .
− If a wash stop input switch is closed (see Section 6.4), indicating e.g. 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