
Maintenance
ECA 450
66
Instruction 0024-9400
4.4.2 Nitric Oxide Sensor Battery Replacement
A single lithium battery, located on top of the Nitric Oxide printed circuit
board, applies a bias voltage to the NO sensor to prevent the sensor from
destabilizing when the analyzer is turned off. This battery has a life
expectancy of at least 2 years.
Replace the Nitric Oxide bias battery toward the end of its life expectancy, or
when its voltage drops below 2 volts.
Tip:
Replace the bias battery whenever the NO sensor is replaced.
Material Required:
• Medium Phillips screwdriver
• Bias battery (refer to Section 6.1)
Procedure:
1.
Remove two screws from sensor-cover plate, and then remove plate to
gain access to sensor compartment. See Figure 4-3.
2.
Remove old battery from its holder on the Nitric Oxide printed circuit
board.
3.
Insert new battery (positive side facing upwards) into holder.
4.
Install sensor-cover plate that was removed in Step 1.
5.
Before powering up and using the analyzer, allow the Nitric Oxide sensor
to stabilize as described below. Note that recalibration of the Nitric Oxide
sensor is not required after replacing its bias battery.
Depending on how long the Nitric Oxide sensor was without bias voltage,
the time required for the sensor to completely stabilize varies from less
than a minute to several days. Typical stabilization times are shown
below. Generally, however, the sensor is sufficiently stable after 4 hours
for measurement purposes.
Bias removed for . . .
Stabilization time
Less than 15 minutes
Less than 1 minute
Less than 1 hour
Less than 5 minutes
Less than 2 days
Less than 4 hours
Greater than 2 days
Up to 2 days