ENERAC 700, Instruction Manual

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B. Nitric oxide sensor (NO sensor)
This is a proprietary four-electrode sealed electrochemical cell that contains a
temperature sensor embedded within the sensor element. Its PCM is
different from the other sensors in that it is made of aluminum, to allow
efficient heat transfer. The NO sensor is temperature controlled by a
thermoelectric Peltier element located where the sensor meets the manifold.
The sensor temperature is maintained below 25 °C to limit unpredictable
temperature-based base- line drifts, in accordance with the EPA’s CTM-022
protocol requirements. This eliminates the requirement of repeated ambient
temperature recordings, described in CTM-32 and CTM-24.
The sensor section contains a proprietary design consisting of four
electrodes made of exclusively noble metals.
Sensor life is estimated at 2
years.
The SEM
TM
NO sensor of the ENERAC Model 700 is superior to the typical
electrochemical type sensor in accuracy, interference rejection, and its
design for continuous operation. Its inboard disposable filter has an
estimated life in excess of 100,000 PPM-hours against sulfur dioxide.
This sensor requires a constant bias voltage for proper operation. This
voltage is supplied to the sensor, even when the instrument is turned off. It
draws a small amount of current and will drain the batteries completely in
about 10 months. For this reason the unit should always be given a fresh
charge once every 2-3 months.
C. Nitrogen dioxide sensor (NO
2
sensor)
This is an electrochemical cell with its PCM an integral part of the sensor
assembly. There is no Precision Control Module or interference rejection
filter media for it. It has a standard range of 0 to 500 PPM. Its life is
estimated at two years.