YOKOGAWA EXAxt ZR402G, Руководство пользователя

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<12. Troubleshooting>
12-9
IM 11M12A01-04E 11th Edition : Jul. 19, 2017-00
(2) Moisture content in a reference gas changes (increases) greatly.
If air at the detector installation site is used for the reference gas, large change of moisture
in the air may cause an error in measured oxygen concentration value (vol% O
2
).
When this error is not ignored, use a gas in which moisture content is constant such as
instrument air in almost dry condition as a reference gas.
In addition, change of moisture content in exhaust gas after combustion is also considered
as a cause of error. However, normally this error is negligible.
(3) Calibration gas (span gas) is mixing into the sensor due to leakage.
If the span gas is mixing into the sensor due to leakage as a result of failure of the valve
provided in the calibration gas tubing system, the measured value shows a value a little
higher than normal.
Check valves (needle valves, check valves, solenoid valves for automatic calibration,
etc.) in the calibration gas tubing system for leakage. For manual valves, check them after
confirming that they are in fully closed states. In addition, check the tubing joints for leakage.
(4) The reference gas is mixing into the measuring gas and vice versa.
Since the difference between oxygen partial pressures on the sensor anode and cathode
sides becomes smaller, the measured value shows a higher value.
An error which does not appear as the Error-1 may occur in the sensor. Sample gas and/or
the reference gas may be leaking. Visually inspect the sensor. If any crack is found, replace
the sensor assembly with a new one.
(Note) Data such as cell robustness displayed in the detailed data display should also be used for deciding sensor quality as references.
12.3.2 Measured Value Lower (Higher for Humidity Analyzer)
Than True Value
<Causes and Measures>
(1) The measuring gas pressure becomes lower.
Where an increment of the measured value due to pressure change cannot be neglected,
take measures referring to subsection 12.3.1 (1).
(2) Moisture content in a reference gas changes (decreases) greatly.
If air at the analyzer installation site is used for the reference gas, large change of moisture
content in the air may cause an error in measured oxygen concentration value (vol% O
2
).
When this error is not ignored, use a gas in which moisture content is constant such as
instrument air in almost dry condition as a reference gas.
In addition, change of moisture content in exhaust gas after combustion is also considered
as a cause of error. However, normally this error is negligible.
(3) Calibration gas (zero gas) is mixed into the sensor due to leakage.
If the zero gas is mixed into the detector due to leakage as a result of failure of the valve
provided in the calibration gas tubing system, the measured value shows a value a little
lower than normal.
Check valves (needle valves, check valves, solenoid valves for automatic calibration,
etc.) in the calibration gas tubing system for leakage. For manual valves, check them after
confirming that they are in fully closed states.
(4) Combustible components exist in the sample gas. If combustible components exist in the
sample gas, they burn in the sensor and thus oxygen concentration decreases. Check that
there are no combustible components.
(5) Temperature of the sensor cell reaches 750 °C or more.
If the sensor temperature is 750°C or higher, this may indicate that sample gas has leaks
into the reference gas side, corrosion. Also check that the thermocouple resistance is no
greater than 15Ω.