Yokogawa Integral Oxygen Analyzer ZR202 - Manual (Page 130)

<11. Inspection and Maintenance>
11-1
IM 11M12A01-04E
11. Inspection and Maintenance
This chapter describes the inspection and maintenance procedures for the EXAxt ZR Zirconia Oxygen
Analyzer to maintain its measuring performance and normal operating conditions.
CAUTION
When checking the detector, carefully observe the following:
(1) Do NOT touch the probe if it has been in operation immediately just before being checked. (The
sensor at the tip of the probe heats up to 750°C during operation. If you touch it, you will get
burned.)
(2) Do not subject the probe to shock or cool it rapidly.
The sensor is made of ceramic (zirconia). If the detector is dropped or bumped into something,
the sensor may be damaged and no longer work.
(3) Do not reuse a metal O-ring to seal the cell assembly. If you replace the cell or remove it from the
probe for checking, be sure to replace the metal O-ring. Otherwise, the furnace gas may leak,
and then the leaking corrosive gas will cause the built-in heater or thermocouple to disconnect,
or the detector may corrode.
(4) Handle the probe with care so that the dust filter mounted screws on the tip of the probe do not
hurt your finger(s).
(5) Before opening or closing the terminal box, first remove dust, sand, or the like from the terminal
box cover.
11.1 Inspection and Maintenance of the Detector
11.1.1 Cleaning the Calibration Gas Tube
The calibration gas, supplied through the calibration gas inlet of the terminal box into the detector,
flows through the tube and comes out at the tip of the probe. The tube might become clogged with
dust from the sample gas. If you become aware of clogging, such as when a higher pressure is
required to achieve a specified flow rate, clean the calibration gas tube.
To clean the tube, follow these steps:
(1) Remove the detector from the installation assembly.
(2) Following Section 11.1.2, later in this manual, remove the four bolts (and associated spring
washers) that tighten the sensor assembly, and the pipe support as well as the U-shaped pipe
with filter .
(3) Use a rod 2 to 2.5 mm in diameter to clean the calibration gas tube inside the probe. In doing
this, keep air flowing from the calibration gas inlet at about 600 ml/min and insert the rod into the
tube (3-mm inside diameter).
However, be careful not to insert the rod deeper than 40 cm.
(4) Clean the U-shaped pipe. The pipe can be rinsed with water. However, it should be dried out
thoroughly before reassembly.
(5) Restore all components you removed for cleaning. Follow Section 11.1.2 to restore all
components in their original positions. Be sure to replace the O-ring(s) with new ones.