Metek 920, Operator'S Manual With Essential Health And Safety Requirements

Page: 149 / 278

Controller / User Interface | 4-41
Analyzer Control Mode (Automatic Control by Analyzer)
When the analyzer’s Flow Control mode is set to Analyzer Control , the
analyzer automatically determines and sets the mode of operation by
monitoring the state of the Fault alarm relay contacts.
If there are no active Fault alarms, the analyzer will operate in Analyzer
Control mode ( automatic Sample ). When in automatic Sample mode, there
is no indicating character on the User Interface.
If the analyzer detects a Fault alarm while it is operating in Automatic
Sample mode,
S
is displayed on the top-right line of the User Interface.
When this occurs, the analyzer will switch to automatic Backpurge , and
“ b ” is displayed on the top-left line (as opposed to a “ B ”, which indicates
manual Continuous Backpurge ). The analyzer will not switch back to
automatic Sample mode until the cause of the alarm has been corrected
(cleared).
If a fault alarm is triggered, the analyzer will switch from automatic
Sample mode (sample gas flowing) to automatic Backpurge mode
(zero gas flowing). If the alarm automatically clears (resets) itself, the
analyzer will switch back to
automatic Sample mode. If the analyzer
is in automatic Backpurge mode, sample gas stops flowing and the
sample system is flushed with Zero gas until the alarm has been man-
ually corrected, at which time the analyzer switches back to
automat-
ic Sample mode. If this condition recurs, refer to Troubleshooting
and Diagnostics in Chapter 5 and review the corrective action for
the corresponding alarm, for information on how to troubleshoot the
condition.
Because a low temperature is defined as a fault, the analyzer will switch to
automatic Backpurge mode for the length of time required for all tempera-
ture zones to stabilize at their Set Points.
To set the analyzer’s Flow Control mode to Analyzer Control mode and
return to CAL mode normal display, press:
CAL>F5 2 Del 0 Ent Ent

NOTE