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Alarms


Alarms

The following table describes the detector alarms and corresponding screens.

During an alarm condition, the detector activates the backlight and displays the current ambient gas reading.

If more than one type or level of alarm exists simultaneously, a multi-gas alarm will result.

To change the factory-set alarm setpoints, refer to Calibration and Setting Alarm Setpoints.

Table 6. Alarms

Alarms Display Alarms Display
Low Alarm:
  • Fast beep
  • Slow flash
  • and target gas bar flash
  • Vibrator alarm activates
 High Alarm:
  • Constant beep
  • Fast flash
  • and target gas bar flash
  • Vibrator alarm activates
STEL Alarm:
  • Fast beep
  • Slow flash
  • and target gas bar flash
  • Vibrator alarm activates
 TWA Alarm:
  • Fast beep
  • Slow flash
  • and target gas bar flash
  • Vibrator alarm activates

Table 6. Alarms (cont.)

Alarms Display Alarms Display
Multi-Gas Alarm:
  • Alternating low and high alarm beep and flash
  • Slow flash
  • and target gas bar flash
  • Vibrator alarm activates
 Over Range Alarm:(Over Level Exposure)
  • Fast beep and flash
  • Fast flash
  • and target gas bar flash
  • Vibrator alarm activates
Sensor Alarm:
  • One beep every 15 seconds
  • Slow flash
  • FAIL flashes above the failed sensor
 Automatic Shutdown Alarm:
  • Eight beeps and flashes
  • Slow flash
  • displays
  • Vibrator alarm temporarily activates
Low Battery Alarm:
  • One beep and two flashes every 25 seconds
  • flashes
 Normal Shutdown:
  • Three beeps and flashes

Table 6. Alarms (cont.)

Alarms Display Alarms Display
Confidence Beep:
  • Two fast beeps every 10 seconds
 MMC Fail Alarm:
  • One beep every 5 seconds
  • flashes
Alarms Displays
Pump Alarm:
  • Two fast beeps and alternating flashes
  • Vibrator alarm activates
  • and flash

Note

If the latched alarm function is activated, the audible and visual alarms continue to beep and flash until the alarm condition is acknowledged. To acknowledge a latched alarm, press C. The alarms cannot be deactivated if an alarm condition exists.

If the stealth option is enabled, the detector only vibrates during an alarm; the audible and visual alarms are disabled.

Gas Exposures Computed

Warning

To avoid possible personal injury, do not deactivate the detector during a work shift. TWA and STEL readings reset if the detector is deactivated for more than 5 minutes.

Table 7. Computed Gas Exposures

Gas Exposure Description
TWA (toxic only) Time-weighted average (TWA) based on accumulated exposure to toxic gases averaged over a work day according to OSHA or ACGIH method.
STEL (toxic only) Short-term exposure limit (STEL) to gas based on a 5-15 minute user selectable period.
Maximum* (peak) Maximum (MAX) concentration encountered during work shift.

*For oxygen, it is the highest or the lowest concentration encountered.

Viewing Gas Exposures

Press and hold until the MAX gas exposures screen displays.

The TWA gas exposures display next.

Lastly, the STEL gas exposures display.

Clearing Gas Exposures

The exposures automatically clear after 5 minutes of the detector being deactivated.

To clear the MAX, TWA, and STEL exposure readings immediately, press and hold and simultaneously. The detector displays the following screen during the countdown.

Note

Hold and for the entire countdown, otherwise the MAX, TWA, and STEL exposure readings will not clear.

Gas Alarm Setpoints

The gas alarm setpoints trigger the gas alarms and are described in Table 8.

Table 8. Gas Alarm Setpoints

Alarm Condition
Low alarm Toxics and combustibles: Ambient gas level above low alarm setpoint.
Oxygen: Ambient gas level may be set above or below 20.9%.
High alarm Toxics and combustibles: Ambient gas level above high alarm setpoint.
Oxygen: Ambient gas level may be set above or below 20.9%.
TWA alarm Toxic only: Accumulated value above the TWA alarm setpoint.
STEL alarm Toxic only: Accumulated value above the STEL alarm setpoint.
Downscale alarm Toxic: If sensor reading is negative (half of the TWA setpoint).
LEL: If sensor reading is negative (half of the low alarm setpoint).
Multi-gas alarm Two or more gas alarm conditions.

Viewing the Alarm Setpoints

To view the current alarm setpoints for all of the sensors, press during normal operation.

The TWA, STEL, low, and high alarm setpoint screens display in the following order:

If a correction factor has been applied to a sensor, one of the following screens display indicating the sensor and gas type.

Resetting Gas Alarm Setpoints

Note

Standard factory alarm setpoints vary by region.

The following table lists the factory alarm setpoints according to the Occupational Safety and Health Association (OSHA) settings.

Table 9. OSHA Sample Factory Alarm Setpoints

Gas TWA STEL Low High
O2 N/A N/A 19.5% vol. 23.5% vol.
LEL N/A N/A 10% LEL 20% LEL
CO 35 ppm 50 ppm 35 ppm 200 ppm
H2S 10 ppm 15 ppm 10 ppm 215 ppm
PH3 0.3 ppm 1.0 ppm 0.3 ppm 1.0 ppm
SO2 2 ppm 5 ppm 2 ppm 5 ppm
Cl2 0.5 ppm 1.0 ppm 0.5 ppm 1.0 ppm
NH3 25 ppm 35 ppm 25 ppm 50 ppm
NO2 2.0 ppm 5.0 ppm 2.0 ppm 5.0 ppm
HCN 4.7 ppm 10.0 ppm 4.7 ppm 10.0 ppm
ClO2 0.1 ppm 0.3 ppm 0.1 ppm 0.3 ppm
O3 0.1 ppm 0.1 ppm 00.1 ppm 0.1 ppm
VOC 50 ppm 100 ppm 50 ppm 100 ppm

To change the factory-set alarm setpoints, refer to Calibration and Setting Alarm Setpoints.

Note

To disable an alarm, set the alarm setpoint to 0(zero).

Stopping a Gas Alarm

The low and high alarms stop when the ambient gas level returns to below the low alarm setpoint.

Note

If alarms are set to latch, press to reset the alarms.

The TWA and STEL alarms can be stopped either by

  • clearing the MAX, TWA, and STEL peak exposures (refer to Clearing Gas Exposures), or
  • deactivating the detector for 5 minutes (minimum) and then reactivating it again.

Sensor Alarm

The detector tests for missing or defective sensors during the activation self-test. If a sensor fails the self-test, the detector displays FAIL above the failed sensor. Refer to Troubleshooting.

Pump Alarm

The external pump draws air over the sensors continually. If the pump stops operating or becomes blocked, the detector activates the pump alarm. The following screens display.

The pump alarm continues until the blockage is cleared or it is acknowledged by pressing . If is pressed, the detector automatically launches a pump test to reset the pump module.

Refer to Pump Test for more information. If the pump test is successful, the detector returns to normal operation, otherwise the pump alarm continues.

Low Battery Alarm

The detector tests the batteries upon activation and continuously thereafter. Battery power is continually displayed during normal operation. If the battery voltage is low, the detector activates the low battery alarm.

The low battery alarm continues until the batteries are replaced/charged, or until the battery power is almost depleted. If the battery voltage becomes too low, the detector deactivates.

Note

Typically, the low battery alarm continues for 30 minutes before the detector automatically deactivates.

Automatic Shutdown Alarm

If the battery voltage is in immediate danger of falling below the minimum operating voltage, the audible alarm beeps eight times and the visual alarm flashes eight times. After 3 seconds, the LCD deactivates and the detector exits normal operation.

To replace or charge the batteries, refer to Replacing/Charging the Batteries.