YOKOGAWA ZO21DW, User Manual, Page: 29 / 39

<6. OPERATION>
6-2
IM 11M03A02-00E
6.2 Stationary Operation
6.2.1 Checking Operating Conditions
In order to maintain normal operating conditions, determine which items are to be inspected
periodically, and check them regularly for errors.
Items recommended for periodic inspections are as follows for your reference. For maintaining or
recovering performance, see Chapter 7.
Table 6.1 Example of Items for Periodic Inspection
Inspection Item Purpose & detail of inspection
Inspection
interval
System
1
System
2
System
3
Complete closing
of calibration gas
inlet
To prevent condensation which may break
sensor. Check for a complete closing of needle
valve.
1 to 7 days ○
Set flow rate of
flow setting unit
Check that flow is about 800 ml/min. and
600ml/min. for reference gas and calibration
gas, respectively for correctly measured and
calibrated values.
1 to 7 days ○ ○
Pressure in the
calibration gas
cylinder
To determine the intervals between
replacement of calibration gas (zero gas)
cylinders. Specify min. pressure and check for
higher pressure.
1 to 2
week
○ ○
6.2.2 Stopping and Restarting Operations
<Operation stoppage>
Before stopping operations, it is important for you not to make the detector sensor inoperable.
If you stop the operation of the zirconia oxygen analyzer at the same time as the boiler or
furnace, etc., condensation forms in the sensor and dust adheres to it. If you restart operations
with the sensor in this state, as it heats up to 750°C, it causes dust to accumulate which
significantly deteriorates its performance. In an extreme case with a lot of condensation, the
analyzer may break. To prevent such an occurrence, you have to take the following steps to stop
the equipment :
(1) Do not stop to supply reference gas to keep the stop valve in the discharge tube of the
reference gas open because the measuring gas may flow backward into the detector.
(2) Keep the power supply to the analyzer ON as long as possible. If this is impossible, remove
the detector.
(3) If both of the above are impossible, keep air flowing into the calibration gas piping at a rate
of about 600 ml/min.
<Operation restart>
If none of the above precautions for stopping operations can be done, supply air into the
calibration gas piping for 5 to 10 minutes at a rate of about 600 ml/min.