Hach 1950Plus, Инструкция по эксплуатации инструмента, Страница: 141 / 188

Section 8
Page 141
UVTOCTroubleshooting and Service.fm
Service Menus
Referring to the menus above, the LO/HI indication is an input status, which
will toggle for 0.5 seconds each time a bubble is detected. This is used verify
correct operation during commissioning of an analyzer. The number is the
threshold bubble counts per minute which will cause the associated flow
event, and is different for every analyzer configuration. Sensitivity to flow
failure can be decreased by increasing the number, and increased by
decreasing the number. Setting the threshold to 0, will disable the bubble
counter event completely. The numeric value can be adjusted by pressing
ENTER
and then using the
UP
and
DOWN
keypads. Pressing
ENTER
again
locks the new number. The threshold can be set from 0 (disable) to 200.
Because of the nature of some sample compositions, it is not possible to
guarantee that the default bubble threshold value is always suitable, or even
that the detection method will not cause false triggering. Refer to
Table 15 for
default bubble threshold values.
Single Stream Operation— When Online, if the analyzer detects more
bubbles per minute than the threshold value, the analyzer will go Offline, with
the pumps still running and the UV lamps off. While Offline, if the analyzer
detects a bubble count per minute less than the threshold, the analyzer will
enter a Purge Period then return to Online mode. If the bubble count is
exceeded in the last minute of the Purge, the analyzer will return to
Offline mode.
Dual Stream Operation— When Online in a stream A, if the analyzer detects
more bubbles per minute than the threshold value, the analyzer will switch to
the other stream, stream B, and enter a purge. Following the Purge Period,
the analyzer will go Online on stream B. On completion of the Purge Period,
the analyzer will revert to the original stream, stream A, enter a Purge and go
online to stream A only if the bubble count is less than the threshold value. If
the bubble count is exceeded the analyzer with revert back to stream B. The
analyzer will thus act appropriately based on the last minute of the Purge
Period for each stream. Note that the UV lamps will be on when Purging is
being done so that if both streams are causing errors the lamps are on
continually. For this reason, this condition should not be ignored.
Purge Period Operation— All bubble issues are ignored during the Purge
Period except for the last minute of the Purge period. The analyzer will
continue to cause an event based on the bubble count/ bubble threshold
values during the last minute of the Purge Period.
S p a r g e r f l o w
L O 15
U V f l o w
H I 30