Instruction manual

SM425 INSTRUCTION MANUAL 10.0 OTHER FUNCTIONS
Store the standard gas unit with the gas cylinder mounted where the ambient temperature does not
exceed 40°C. Otherwise, the gas cylinder may explode. Store the spare gas cylinders under the same
condition.
10.6 Methods of Operating Valves in the ZA8F Flow Setting
Unit
The ZA8F Flow Setting Unit is used as a calibration device for analyzer conforming to System 2.
Calibration of a System 2 is a manual operation. The Flow Setting valve must be adjusted each time a
calibration is made (starting and stopping the calibration gas flow and adjusting the flow rate). This
applies even if you are using the SM425CAL Autocalibration Unit. For operation of the converter, see
Section 1.44.
10.6.1 Preparation Before Calibration
To operate the ZA8F Flow Setting Unit, initial calibration steps are as follows:
1. Verify the zero gas flow setting valve in the unit is completely closed. 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. Verify 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 Span Gas Flow Valve Adjustment
The following description assumes that instrument air, the same as the reference gas, is used as the
span gas.
1. When the display screen appears as shown in Figure 10-15 during calibration, open the span gas
flow setting valve unit and adjust the flow rate to 600 ± 60 ml/min. Turn the valve slowly
counterclockwise after loosening any lock nut. Check the flow rate using the calibration
flowmeter. Adjust the measurement gas pressure to obtain pressures as listed in
2. Table 10-6 ± 10%.
Table 10-6 Setting flow for high pressure (span)
3. Adjust the flow rate and select Valve opened from the Manual Calibration display screen. Check
the Trend graph display screen to verify the measured value has stabilized. Then press the
[Enter] key. The Manual calibration display screen should appear as shown in Figure 10-16.
4. Close the span gas flow setting valve. Tighten any lock nut to prevent leakage of span gas into
the sensor during process gas measurement.
10.6.3 Zero Gas Flow Valve Adjustment
Adjust the zero gas flow setting valve during zero-point calibration using the following procedure:
172 42500001 REV A