Yokogawa Integral Oxygen Analyzer ZR202 - Manual (Page 128)

<10. Other Functions>
10-19
IM 11M12A01-04E
10.6 Methods of Operating Valves in the ZA8F Flow
Setting Unit
The ZA8F Flow Setting Unit is used as the calibration equipment for a system conforming to System
2. Calibration in such a system is to be manually operated. So, you have to operate the valve of the
Flow Setting Unit each time calibration is made (starting and stopping the calibration gas flow and
adjusting the flow rate). For the operation of the converter, refer to Section 7.10.
10.6.1 Preparation Before Calibration
To operate the ZA8F Flow Setting Unit, prepare for calibration as follows:
(1) Check for a complete closing of the zero gas flow setting valve in the unit and open the regulator
valve for the zero gas cylinder until the secondary pressure is sample gas pressure plus approx.
50 kPa (or sample gas pressure plus approx. 150 kPa when a check valve is used, maximum
pressure rating is 300 kPa ).
(2) Check that the oxygen concentration of the zero gas and span gas (instrument air 21 vol% O
2
) in
the cylinder is set for the converter.
10.6.2 Operating the Span Gas Flow Setting Valve
The following description is given assuming that instrument air, the same as the reference gas, is used
as the span gas. For more details, see Section 7.10.2, “Manual Calibration,” earlier in this manual.
(1) When “OPEn” and the “measured oxygen concentration” appear alternately during the span
calibration, open the span gas flow setting valve of the flow setting unit and adjust the flow rate to
600 ± 60 ml/min.
Loosen the lock nut if the valve shaft has a lock nut, and turn the valve regulator slowly
counterclockwise. To check the flow rate, use the calibration flowmeter. If the sample gas
pressure is extremely high, adjust the sample gas pressure to obtain pressures (listed in Table
10.8) ± 10%.
Table 10.8
Sample gas pressure, (kPa) 50 100 150 200 250
Flow rate, (ml/min) 500 430 380 350 320
(2) Adjust the flow rate. After the measured oxygen concentration has stabilized, touch the [ENT]
key, then all the digits will flash. Touch the [ENT] key again to display “ZEro Y.”
(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 calibration in the following procedures:
(1) When the “OPEn” and the “measured oxygen concentration” appear alternately during
calibration, open the zero gas flow setting valve of the flow setting unit and adjust the flow rate to
600 ± 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 flowmeter. If the sample gas pressure
is extremely high, adjust the sample gas pressure to obtain pressures (listed in Table 10.9) ±
10%.