Resetting Latched Alarms - Emerson Rosemount 928 Reference Manual

Operation and maintenance
February 2023
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Verify that gas concentrations in the area have dissipated to a safe level before clearing
local or digital alarms.
• Gas Concentration Alarm Configuration: Displays the configuration settings for local
and digital gas concentration alarms when the detected gas concentration level
exceeds the specified high concentration threshold. This option allows configuring the
following gas alarm options:
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• Configurable Update Rate: Specifies the wireless update rate. The range is 1 second
to 60 seconds. The default update rate is eight seconds. Refer to
considerations.
• Gas Concentration Filtering: This setting controls the filtering of gas concentration
measurements. By default,
is temporarily disabled during calibration. The options are:
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5.4

Resetting latched alarms

You can clear latched alarms by removing and reinstalling the power module to power the
device off and back on again.
Refer to
remain latched following a device reset or power mode failure. You can also clear latched
128
Initiate action (for example, close valves, initiate facility evacuation, call emergency
services)
WARNING
High Concentration Threshold: Gas concentration level alarm is activated when the
detected gas concentration exceeds the specified high concentration threshold.
Alarm Latching: If you select
until you manually clear the alarm. If you select
automatically when the gas concentration level dissipates below the specified high
concentration threshold.
Alert Handling: If you select
alarm in case of a device failure alert. If you select
, the device only issues an alarm when the detected gas concentration level
Alarms
exceeds the specified alarm threshold.
No Filtering: When you select this setting, all gas concentration measurements are
reported at their actual values.
Truncate Values Below Zero: Gas concentration measurements less than zero are
reported as zero.
Report Small Readings as Zero: Gas concentration measurements near zero but
within the degree of uncertainty are reported as zero. Refer to
degree of uncertainty based on gas type.
Table 5-1: Degrees of Uncertainty
Gas type
Hydrogen sulfide (H S)
2
Oxygen (O )
2
Carbon monoxide (CO)
Remove power module
Latch Gas Alarm
Not Latched
Alert Triggers Gas Alarm
Report Small Readings as Zero
Degree of uncertainty
0.5 ppm
0.2 ppm
3 ppm
and Install the power module. Latched alarms do not
Reference Manual
00809-0100-4928
, the alarm output is latched
, the alarm clears
, the device issues an
Alerts do not Trigger Gas
Update rate
is selected. Filtering
Table 5-1 for the
Emerson.com/Rosemount