1 preparation before calibratin, 2 operating the span gas flow setting valve – Yokogawa Single Channel Oxygen Analyzer System ZR22/ZR402 User Manual

Page 170

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IM 11M13A01-02E

10-19

10. Other Functions

10.6 Methods of Operating Valves in the ZA8F Flow Setting

Unit

The ZA8F Flow Setting Unit is used as a calibration device 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 each time calibration is made (starting and stop-
ping the calibration gas flow and adjusting the flow rate). This applies even if you are
using the ZR40H Autocalibration Unit. For operation of the converter, see Section 7.12,
earlier in this manual.

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
measured gas pressure + approx 50 kPa (or measured 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 in 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.

(1) When the display shown in Figure 10.15 appears during calibration, open the span

gas flow setting valve of the flow setting unit and adjust the flow rate to 600

±

60

ml/min. Turn the valve slowly counterclockwise after loosening the lock nut if the
valve has a lock nut. To check the flow rate, use the calibration flow meter.

(2) Adjust the flow rate and select Valve opened from the Manual calibration display.

Check the Trend graph display to see that the measured value is stabilized. Then
press the [Enter] key. The Manual calibration display shown in Figure 10.16 appears.

(3) Close the span gas flow setting valve to stop the span gas (air) flow. If the valve has

a lock nut, be sure to tighten the lock nut to prevent any leakage of span gas into the

sensor during measurement.

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