EAGLE 2 Operator’s Manual
Instrument Description • 17
CO and H
2
S Sensors
The CO and H
2
S sensors are electrochemical sensors that consist of three precious metal
electrodes in a dilute acid electrolyte. A gas permeable membrane covers the sensor face
and allows gas to diffuse into the electrolyte. The gas reacts in the sensor and produces a
current proportional to the concentration of the target gas. The current is amplified by the
EAGLE 2’s circuitry, converted to a measurement of gas concentration, and displayed on
the LCD.
The CO and H
2
S sensors are physically very similar. Except for their markings and wire
colors, they look almost identical. A three-position connector at the end of a 2-wire cable
from each sensor plugs into a socket on the main PCB. The sockets on the main PCB for
the CO and H
2
S sensors are labeled
CO
and
H2S.
Normally, the CO connector plugs into
the
CO
socket and the H2S plugs into the
H2S
socket. However, because of the way that
the main PCB circuitry is arranged, if the CO sensor is plugged into the H2S socket and
the H2S sensor is plugged into the CO socket, the sensors will still operate properly and
the CO and H2S readings will still appear on the channels that are programmed for those
gases.
LCD
A digital LCD (liquid crystal display) is visible through a clear plastic window in the top
case. The LCD simultaneously shows the gas reading for all installed sensors. The LCD
also shows information for each of the EAGLE 2’s operating modes.
Control Buttons
Four control buttons are located below the LCD. They are, from left to right, POWER
ENTER RESET, DISPLAY ADJUST NO, AIR
▲
YES,
and RANGE
▼
SHIFT.
Table 3: EAGLE 2 Control Button Functions
Button
Function(s)
POWER ENTER
RESET
• turns the EAGLE 2 on and off
• silences and resets audible alarm if Alarm Latching is set to
Latching
and Alarm Silence is set to
ON
• enters instructions, values, and settings into the EAGLE 2’s
microprocessor
DISPLAY ADJUST
NO
• activates Display Mode
• silences and resets audible alarm if Alarm Latching is set to
Latching
and Alarm Silence is set to
ON
• enters instructions into the EAGLE 2’s microprocessor
AIR
▲
YES
• activates the demand zero function (adjusts the EAGLE 2’s
fresh air reading)
• silences and resets audible alarm if Alarm Latching is set to
Latching
and Alarm Silence is set to
ON
• enters instructions into the EAGLE 2’s microprocessor
• moves the cursor on the LCD up the screen
• increases the value of a parameter available for adjustment
• scrolls through parameter options
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