YOKOGAWA EXAxt ZR22G, Руководство пользователя, Страница: 192 / 211

<12. Troubleshooting>
12-11
IM 11M12A01-02E 16th Edition : Mar. 19, 2020-00
<Corrective action>
When the battery low alarm occurs, remember that the battery cannot be replaced by the user.
Contact your Yokogawa service representative.
NOTE
Battery life varies with environmental conditions.
* If power is applied to the instrument continuously, then the battery should not run down, and
life is typically about ten years. However the battery will be used during the time interval
between shipment from the factory and installation.
* If power is not applied to the instrument, at normal room temperatures of 20 to 25°C then
battery life is typically 5 years, and outside this range but within the range -30 to +70°C then
battery life is typically 1 year.
12.3 Countermeasures When Measured Value
Shows Error
The causes that the measured value shows an abnormal value is not always due to instrument
failures. There are rather many cases where the causes are those that measuring gas itself
is in abnormal state or external causes exist, which disturb the instrument operation. In this
section, causes of and measures against the cases where measured values show the following
phenomena will be described.
(1) The measured value is higher than the true value.
(2) The measured value is lower than the true value.
(3) The measured value sometimes shows abnormal values.
12.3.1 Measured Value Higher (Lower for Humidity Analyzer)
Than True Value
<Causes and Countermeasures>
(1) The measuring gas pressure becomes higher.
The measured oxygen concentration value X (vol%O
2
) is expressed as shown below,
when the measuring gas pressure is higher than that in calibration by ∆p (kPa).
X=Y [ 1+ (∆p/101.30) ]
where Y: Measured oxygen concentration value at the same pressure as in calibration
(vol%O
2
).
Where an increment of the measured value by pressure change cannot be neglected,
measures must be taken.
Investigate the following points to perform improvement available in each process.
• Is improvement in facility’s aspect available so that pressure change does not occur?
• Is performing calibration available under the average measuring gas pressure
(internal pressure of a furnace)?
(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.