YOKOGAWA MG8G, User Manual, Page: 56 / 63

<12. TROUBLESHOOTING>
12-3
IM 11P03A03-01E 6th Edition : Jan. 26, 2022-00
n
Calibration Coefficient Errors (E-50, E-51)
A calibration coefficient error occurs if the calibration coefficient obtained in zero or span
calibrations is outside the normal range. A zero calibration coefficient error occurs if the zero
calibration coefficient is outside of ±1.25% O
2
. A span calibration coefficient error occurs if the
span calibration coefficient is outside the rage of 0.9 to 1.09. For details, refer to Chapter 9,
Calibration.
When the error occurs, the FAIL lamp turns on and the FAIL contact is activated only when the
semiautomatic or automatic calibration function is enabled. In the case of manual calibration, the
DATA display shows “E-5.” Possible causes are:
• The calibration gas concentration set in the instrument does not agree with the actual
concentration of the calibration gas used.
• The pressure of the auxiliary gas was lower than the specified one.
• Zero or span gas was not being supplied.
• In manual calibration, a zero calibration was conducted with span gas flowing, or vice versa.
Remove the causes and reset the error status by performing zero and span calibration again. If
the calibration coefficient is outside the specification range due to a sensor drift or characteristics
change with time, initialize the calibration coefficients and perform zero and span calibration
again.
When the error occurs during semiautomatic or automatic calibration, remove the causes and
reset the error status using the following procedure.
(1) Switch to MAINT mode and enter the password.
(2) Change the Function Number to “42.” The DATA display shows “rES.”
(3) Press the EXEC key to reset the calibration coefficient error status.
12.2 Faulty Readings During Measurement
This section describes faulty readings during measurement and possible causes.
12.2.1 Fluctuations in Readings
• Check that the flow rate of the sample gas is the specified one and is stable.
• Check the piping joints or connections in the line between the auxiliary gas cylinder and the
analyzer for leaks.
• Check that the temperature of the constant temperature chamber is stable.
• Check the power supply voltage for fluctuations.
• Check that the analyzer is not exposed to direct sunlight or radiant heat from a heat source
such as a furnace.
12.2.2 Drift in Readings
Check that the supply pressure of the auxiliary gas is appropriate. If the auxiliary gas pressure
falls below the specified supply pressure, the output will drift as the pressure drops.
12.2.3 Short-Term Shift in Readings
Check that the flow rate of the sample gas is the specified one and is stable. If the flow of the
sample gas containing oxygen is turned off, the reading will shift toward 0% O
2
.