Installation – ZP Oxygen Sensor System Overview 2-37
FlexFit – Linkageless Control – Revision 1.0
PREFERRED
UTILITIES MFG CORPORATION
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ZP Oxygen Sensor Calibration
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.
Due to the excellent stability of the detector, there is very little drift even over long periods of time. Six to twelve-month calibration
checks are normal for natural gas and #2 diesel fuel oil-red units. Fuels with high sulfur, heavy metals or other contaminants should
be checked every three to nine months. The main indicator of the need for re-calibration is cell impedance. Note and record the cell
impedance during start-up and after each re-calibration. Re-calibrate again after cell impedance increases another 100-200 ohms.
The ZP oxygen sensor can be checked or calibrated without being removed from the stack and without shutting down the burner.
To check for proper operation, simply apply a known concentration test gas at 2-3 SCFH (at 1-5 psig) to the ¼" compression tting at
the bottom of the ZP detector. A single test gas can be used to check the operation of the ZP sensor and FlexFit.
Note
New or replacement ZP oxygen probes are factory calibrated. For initial FlexFit
start-ups or adding a ZP oxygen probe to an existing FlexFit installation, the user only
needs enter the values shown on the calibration data tag into parameters "P2.3.9 O2
Cell Slope Cal Data" through "P2.3.12 O2 Cell Cal Data Checksum" on page 4-68.
The calibration procedure uses calibration gases with known oxygen concentrations. This is performed in the eld as required
(every 6-12 months). To perform a ZP oxygen sensor calibration, navigate to Main Menu > Utilities > Oxygen Calibration and follow
the screen prompts. Low and high gas oxygen concentrations are entered into parameters "P2.3.13 O2 Low Cal Gas %" and "P2.3.14
O2 High Cal Gas %" on page 4-68. Calibration test gas that is tested and certied can be obtained from Preferred Instruments. The
calibration can be aborted at any step by selecting the EXIT command. During calibration, the "O2 Trim Option" and "Low O2 Lockout
Option" are bypassed. Oxygen calibration can only be initiated if the FlexFit is in commission mode.
Note
Typical low-range calibra-
tion gas for combustion
applications is 0.4-2%,
and typical high-range
calibration gas is 8%.
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