target gas concentration rise quicker than the Low Alert delay time, the High Alert condition will
be activated immediately, regardless of how much time is left in the delay period. If the unit is
set for “50/100” operation, both the Low Alert and High Alert relays will close simultaneously.
The High Alert relay will remain closed until the target gas concentration drops below the Low
Alert threshold. The High Alert relay will then open and the unit will return to the Low Alert
condition until the delay countdown timer expires.
Alarm
Should the unit remain above High Alert for 15 minutes, the Alarm relay will close, the Alarm
LED will glow, and the internal buzzer will sound, indicating the gas concentration could not be
reduced. The internal buzzer may be silenced by pressing the “ALARM OFF” button on the
front of the detector. Once the concentration drops below the High Alert threshold, the Alarm
relay will open and the detector will return to the High Alert condition.
Proportional Output
The detector is equipped with a proportional output that generates a 4-20 mA, 2-10 VDC, 1-5
VDC, or 0.2-1 VDC signal. This signal is proportional to the concentration of target gas
present at the sensor and may be used for monitoring gas or for controlling a VFD. Not all
systems will accept this signal directly and may need an intermediary controller.
Manual Fan Activation
To manually activate the ventilation system, press the “MANUAL FAN 1” or “MANUAL FAN 2”
button on the front keypad. These buttons will turn on any equipment connected to the Zone 1
and Zone 2 Low Alert relays respectively. Pressing the button a second time will deactivate
the equipment. This feature only works when the target gas concentration is below the Low
Alert threshold for the zone in question. If the target gas concentration is above the setpoint,
the detector will automatically activate any equipment and disable the manual fan activation
buttons. The Low Alert cannot be turned off by the keypad buttons if activated automatically by
the detector.
IOM01
Rev 1.0 – December 22, 2020 24
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