Yokogawa Integral Oxygen Analyzer ZR202 - Manual (Page 150)

IM 11M12A01-05E 10-23
10. Other Functions
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 conform-
ing to System 2. Calibration in such a system is to be manually operated. So, you have
to operate the valve of the Flow Setting each time calibration is made (starting and
stopping the calibration gas flow and adjusting the flow rate).
This applies even if you are using the ZR20H Auto Calibration Unit.
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 equals
[measurement gas pressure plus approx. 50 kPa] (or measured gas pressure plus
approx.150 kPa when acheck 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 refer-
ence gas, is used as the span gas. For more details, see Section 7.10.2, “Manual Calibra-
tion,” 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 6 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 flow meter. If
the measurement gas pressure is extremely high, adjust the measurement gas pressure
to obtain pressures (listed in Table 10.8) 6 10%.
Table 10.8
Measurement gas 50 100 150 200 250
pressure, (kPa)
Flow rate, (ml/min.) 500
430 380 350 320
T10.6.2.EPS
(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”