OPERATION OF VRAE
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2.5 Alarm Signals
The built-in microcomputer constantly updates and monitors
gas concentration and compares it with the programmed
alarm limits (TWA, STEL, and two instantaneous alarm
limits: Low & High). Whenever the concentration exceeds
any of the preset limits, the loud buzzer and red flashing
LED are activated immediately to warn the user of the alarm
condition.
In addition, the VRAE will alarm if any of the following
condition occurs: battery voltage falls below a pre-set
voltage level (4.4 V), LEL sensor is off, pump stalls, reading
is over range or when datalog memory is full. When the low
battery alarm occurs, there will be approximately 20-30
minutes of operating time remaining. When the battery
voltage falls below 4.2 V, the monitor will be turned off
automatically.
Alarm Signal Disabled: It is extremely important to
note that during the following conditions, the alarm
signals are disabled:
1) When entering PC communication standby
mode.
2) When entering Calibration mode.
3) When viewing data in datalog.
4) When printing data to serial printer. (Short
moment)
During these modes of operation, real time monitoring of
the gas concentration stops. None of the gas concentrations
will be calculated, including Peak, STEL and TWA.
Alarm Signal Latching: