Wash Cycle - Vaisala K-PATENTS PR-23 Series Instruction Manual

6 Configuration and calibration

6.5.1 Wash cycle

The wash logic is shown in Figure 6.15 as a flow diagram. The automatic prism wash
cycle (Figure 6.14) consists of three phases: precondition, wash and recovery. The op-
tional preconditioning function is used to e.g. blow out the condensate before wash-
ing. After the preconditioning there is a one-second pause to avoid having both pre-
condition 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 closing an external switch (Remote wash, see Section 6.3.2) or manually
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
PRECOND.
WASH
RECOVERY
INTERVAL
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.
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