Yokogawa Integral Oxygen Analyzer ZR202 - Manual (Page 151)

IM 11M12A01-05E 10-24
(3) Close the span gas flow setting valve to stop the span gas (air) flow. If the valve
shaft has a lock nut, be sure to tighten the lock nut to prevent any leakage of span
gas into the sensor during measurement.
10.6.3 Operating the Zero Gas Flow Setting Valve
Operate the zero gas flow setting valve during zero-point calibration in the following
procedures:
(1) When the “OPEN” and the measured oxygen concentration appearalternately during
calibration, open the zero gas flow setting valve of the flow setting unit and adjust
the flow rate to 600 6 60 ml/min. To rotate the valve shaft, loosen the lock nut if the
valve shaft has a lock nut, and slowly turn it counterclockwise.
(2) To check the flow rate, use an appropriate calibration gas flow meter. If the mea-
surement gas pressure is extremely high, adjust the measurement gas pressure to
obtain pressures (listed in Table 10.9) 6 10%.
Table 10.9
Measurement gas 50 100 150 200 250
pressure, kPa
Flow rate, ml/min. 500 430 380 350 320
T10.6.3.EPS
(3) Adjust the flow rate. After the measured oxygen concentration is stabilized, touch
the [ENT] key, then all the digits will flash. Touch the [ENT] key again to flash
“CAL END”
(4) Close the zero gas flow setting valve to stop the zero gas flow. Be sure to tighten the
lock nut if valve shaft has a lock nut to prevent any leakage of zero gas into the
sensor during measurement. When the stabilization time elapses, the zero calibration
will be complete.
10.6.4 Operation After Calibration
No special operation of the instrument is needed after calibration. However, it is
recommended that the pressure regulator for the zero-gas cylinders be closed because
calibration is not required so often.