10 • Chapter 2: Description
GasWatch 3 for CO and O
2
Control Buttons
Two control buttons, AIR and POWER/MODE, are located below the LCD.
Alarm LEDs
The two alarm LEDs above the LCD alert you to gas, low battery, and failure alarms.
Buzzer
One solid-state electronic buzzer is located inside the case. Sound exits the case through a
hole in the middle front of the case. The buzzer sounds for gas alarms, malfunctions, and low
battery voltage. It also provides feedback for button presses and while in Display, User,
Maintenance, or Gas Select Mode.
Vibrator
A vibrating motor inside the GasWatch 3 case vibrates for gas alarms and unit malfunctions.
NOTE:
If
STEALTH
is set to
ON
, the vibrator only functions when
VIB
in the
STEALTH
Gas Select Mode item is set to
ON
(see pg.94).
Sensor
The sensor retainer holds the sensor in its socket. Only one sensor is needed to detect CO and
O
2
. The dual CO/O
2
sensor is a combination electrochemical cell that consists of two 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 gases. The GasWatch 3’s circuitry
amplifies the current, converts the current to a gas concentration, and displays the
concentration on the LCD.
Table 3: GasWatch 3 Control Button Functions
Button
Function(s)
AIR
• turns on LCD backlight
• resets alarm condition if
LATCH
is set to
ON
in Maintenance Mode
• enters User Mode, Maintenance Mode, and Gas Select Mode when used
with POWER/MODE
• activates the demand zero function (adjusts the GasWatch 3’s fresh air
reading)
• changes the value of a parameter available for adjustment
• scrolls through parameter options
POWER/MODE
• turns the GasWatch 3 on and off
• turns on LCD backlight
• enters and scrolls through Display Mode
• enters instructions into the GasWatch 3’s microprocessor
• resets alarm condition if
LATCH
is set to
ON
in Maintenance Mode
• enters User Mode, Maintenance Mode, and Gas Select Mode when used
with AIR