2-36 Installation – ZP Oxygen Sensor System Overview
FlexFit – Linkageless Control – Revision 1.0
PREFERRED
UTILITIES MFG CORPORATION
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Operation
Internally, the cell and heater operate at 800 °C (1470 °F). The system should remain powered up whenever possible. The heater
uses less than 70 Watts (typically 40-50 W). Do not subject the detector to excessive heat-up and cool-down cycles. If the burner cycles
more than once per day, the ZP oxygen sensor should not be routinely powered-up and down every time the burner cycles on and off.
Flue gas contains a substantial percentage of water vapor. Avoid water condensation in the detector. If the detector is hotter or
the same temperature as the ue gas, the water vapor cannot condense.
Boiler Startup and Shutdown:
If the ZP oxygen sensor is kept in the stack, powered up, and kept at operating temperature, the burner can be started and
stopped at any time without affecting the ZP. Because the cell is at 800 °C, water will not condense inside the ZP Detector.
Insertion into a Hot Stack or Duct:
If a room temperature ZP oxygen sensor is inserted into a hot stack or duct, the cold metal of the ZP can condense the ue gas
water vapor and form liquid water droplets inside the cell or heater. This can damage or corrode the ZP internals. Before inserting a
ZP into a hot stack or duct, power-up the ZP and allow it to reach operating temperature; then insert it into the stack.
Powering Down and Removing a ZP Oxygen Sensor:
CAUTION
The zirconia cell, cell heater, and dust lters are all ceramic and can
be damaged if dropped. Do not drop the ZP sensor assembly or ZP
detector. Package with cushioning before shipping or storage.
If both the boiler and the ZP oxygen sensor are being shutdown, shut down the boiler rst, and keep the ZP powered until the
temperature inside the stack or duct has cooled down to its lowest normal off-line temperature.
If the Boiler is going to remain in operation or if you can’t wait for the stack to cool down, leave the ZP probe in the stack and
cautiously remove the ZP detector from the probe ange with gloved hands to expose it to room air. Then power down the ZP. If the
duct pressure is positive, a cover plate should be used to prevent ue gas ow through the open hole in the probe ange after the
detector is removed.
Maintenance
WARNING
If the ZP sensor is part of an oxygen trim combustion control system or any other
automatic control system, the control system must be disabled, bypassed, or placed
in manual by a qualied control system technician before removing the detector from
the stack or duct. Failure to do so could result in equipment damage, injury, or death.
The detector lter and probe should be inspected and cleaned periodically. See "Table 2 – 1 ZP Sensor Maintenance Periodicity",
below, for maintenance frequency.
Fuel Type Frequency
Solid Fuel or #6 Oil 3 months
Off-gases or #2 Oil 6 months
Natural Gas 12 months
Table 2 – 1 ZP Sensor Maintenance Periodicity
Cleaning the Detector and Probe
1.
WARNING
The ZP ange and tip external surface temperatures approach 200 °F. When
installed, ue gas temperatures can substantially increase the ZP surface tem-
peratures. Always wear protective gloves when handling, to avoid burns.
Remove the ZP detector as described in section "Powering Down and Removing a ZP Oxygen Sensor:".
2. Using clean, dry, compressed air or nitrogen, blow gently across the face of the lter at a 20-degree angle.
3. Using compressed air, blow any dust inside the ZP Probe duct into the stack or duct.
4. If the lter is clogged with dust, replace it with a spare lter.
Note
Liquid water should not
be allowed to contact
the cell. Water vapor
is not a concern.
WARNING
The ZP ange and
tip external surface
temperatures approach
200 °F. When installed,
ue gas temperatures
can substantially increase
the ZP surface tem-
peratures. Always wear
protective gloves when
handling, to avoid burns.
CAUTION
Water in the compressed
air can damage the lter.
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