Teledyne 450H Setup variables VARS, Latch_Alarms, Alarm Beeper, Use Zero Valve, Azero Enable

3.5 Setup variables (VARS)

The setup variables are global settings that can be configured by the user. Note: Do not arbitrarily change these settings since these variables affect the fundamental operation of the instrument. The setup variables are accessed from the main menu by pressing SETUP-VARS.Use the PREV or NEXT buttons to scroll to the desired variable and press EDIT to change the variable. Set the desired value for the variable and press ENTR to save the value. Pressing EXIT aborts the edit screen without changing the value. The setup variables available to the user are listed below along with their description.

0) LATCH_ALARMS

This variable sets the operation of the concentration alarms to either latched or non- latched mode. In latched mode, when a concentration alarm is triggered, the alarm will stay on, or latch, until the user resets the alarm through the ALRM menu on the front panel. When the alarms are set to non-latching mode(LATCH_ALARMS = OFF) the alarms will automatically turn off when the concentration drops back below the alarm threshold value.

1) ALARM_BEEPER

This variable enables or disables the audible beeper that sounds whenever one of the alarms has been triggered. The beeper sounds a slow beep if any of the ‘HI’ alarms are active and sounds a fast beep if any of the ‘HI-HI’ alarms are active.

Note: VAR’s 2-6 apply only to instruments with the Auto-Zero valve option

2) USE_ZERO_VALVE

This variable enables the Auto-Zero valve (if installed) during manual zero calibration (See Section X.X.)

3) AZERO_ENABLE

This variable enables the Auto-Zero function which will perform an automatic zero calibration at the interval specified by the AZERO_FREQ variable. This calibration is performed by admitting externally supplied zero gas into the measurement cell for a period of time specified by the AZERO_DWELL variable and then performing a zero calibration.

4) AZERO_CAL_ENABLE

This variable enables automatic calibation during the Auto-Zero cycle and should be set to ON whenever the Auto-Zero function is enabled.

5) AZERO_FREQ

This variable determines the frequency of the Auto-Zero function in hours. The default value is 24 hours.

6) AZERO_DWELL

P/N 02826B1 Teledyne API Model 450H O3 Monitor Instruction Manual - Page 36