Yokogawa Integral Oxygen Analyzer ZR202 User Manual

Page 140

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IM 11M13A01-04E

10-22

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).

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 [measure-
ment gas pressure plus approx. 50 kPa, measurement gas pressure plus approx. 150
kPa when a check valve is used] (300 kPa maximum).

(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
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

Ϯ 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.

(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
“ZEROY”.

(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 appear alternately during

calibration, open the zero gas flow setting valve of the flow setting unit and adjust
the flow rate to 600

Ϯ 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 flowrate, use an appropriate calibration gas flowmeter.
(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 the 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.

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