8. CALIBRATION
Danger
•When handling standard gas such as calibration gas, read the instruction manual for the standard gas for correct handling. Special care should be taken when handling hazardous gas such as CO gas and the like to prevent poisoning.
8.1Kinds of standard gas
8.1.1When not using zirconia O2 sensor
(1)Zero gas: N2 or atmospheric air/instrument air depending on specification (when without verifi- cation stipulated in the laws for measurement and weighing)
(2)Span gas: Gas of 90% or more full scale for each component, remainder is N2 (span gas for low range will be delivered unless otherwise specified)
8.1.2When using zirconia O2 sensor
(1)Zero gas: Air (Span gas of the O2 analyzer in the laws for measurement and weighing).
(2)Span gas: 1 to 2% O2, remainder is N2. (Zero gas of the O2 analyzer in the laws for measurement and weighing).
Gas of 90% or more full scale for other than zirconia O2 sensor, remainder is N2.
Note: For separately calibrating the low and high ranges of the zirconia O2 sensor, supply 9 to 10% O2 and the remainder N2 for the low range (10%) and use air for the high range (25%).
8.2Preparation of standard gas
The standard gas to be used for calibration is delivered in a separate package from the locker.
Check the kind of standard gas to be used according to the sampling system diagram, and set it at the prescribed location.
Before starting calibration, attach a pressure regulator to the standard gas.
8.2.1How to mount pressure regulator for standard gas cylinder
(1)Before mounting a pressure regulator to the gas cylinder, clean the gas cylinder adapter. Entry of dust into the pressure regulator may result in gas leaks.
(2)If packing is not inserted in the mounting nut for the cylinder or it is damaged, replace it with supplied spare one.
(3)Use a spanner of a proper size, fasten the cylinder mounting nut to the gas cylinder. Mount supplied joint to the outlet according to Item “Sampling system block diagram”.
(4)Loosen the pressure controls and then tighten the outlet controls.
(5)Open a valve of the gas cylinder, and the pressure gauge on the high pressure side indicates a pressure of the gas cylinder by flowing gas into the pressure regulator.
(6)Turn the pressure controls clockwise to increase the secondary pressure; adjust the pressure con- trols so that a pressure gauge on the low pressure side reads 30 kPa.
(7)Open the outlet controls to release gas.
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