Analytical Industries GPR-35 Oxygen Analyzer - Manual (Page 19)

Advanced Instruments Inc.
19
Setting Alarm Values
The alarm setpoint represents a value. The alarm comparator section of the electronics consists of an IC (integrated circuit) with
internal references. The comparator compares the oxygen signal with the internal reference point. Two alarm points are set at
20.0% oxygen CAUTION (or optional HIGH O2 setpoint) alarm and 19.5% oxygen DANGER (or optional LOW 02 setpoint) alarm
in compliance with OSHA specifications. The alarm comparators have a 2% of full scale (0.4% O2) hysteresis to prevent
chattering of the alarm relays. Once the 20.0% CAUTION alarm is activated, the audio alarm and relay will not deactivate until
the oxygen level reaches 20.4%.
Procedure:
The relays are Form C SPDT, normally closed, non-latching, rated at 5A, 30VDC, or 240VAC resistive. Although not
recommended, changes in the alarm set points may be achieved through potentiometers P2 (CAUTION) and P3 (DANGER). In
order to set alarm points other than those set at the factory:
1. Adjust potentiometer P1 (SPAN) to obtain the desired value.
2. Adjust P2 or P3 until the alarm comparator triggers the alarms.
3. Adjust P1 back to 20.9%.
Range Selection
As a single range analyzer there are no other ranges available.
Installation is complete . . .