Teledyne 7500ZA - Infrared Gas Analyzer - Manual (Page 64)

Settings and Calibration Model 7500ZA
Teledyne Analytical Instruments 48
Setting Range
Alarm value: 10-1000 ppm
→ 5 ppm step (initial value: 500 ppm)
Alarm count: 1- 99 times/hr
→ (initial value: 5 times)
Hysteresis : 0-20 % FS → (initial value: 0% of full scale)
[% FS] represents the percentage with the CO range regarded as
100%.
Action of Peak Alarm
If the CO concentration exceeds the alarm value, counting will
begin. If the number of peaks is over the set times per hour, a peak alarm
contact output becomes closed (ON). If it is less than the set times per
hour, it is open (OFF). Since 5 peaks /hour is exceeded in the cross-
hatched area marked (1) in the above graph, the peak count alarm is
turned ON. Since peaks of more than 5 per hour occur at the interval
between (1) and (2), the peak count alarm remains ON whereas at (2),
peaks are reduced to 4 per hour, and the alarm is turned OFF.
Like the hysteresis of the alarm setting, the hysteresis prevents
possible chattering when a measured gas fluctuates about the alarm
value.
* The peak alarm counting logic is not performed during the first 10
minutes after the power is turned ON.