Teledyne 100AH instruction manual 2.4 SO2 Cal Concentration, Formula Values

Teledyne API Model 100AH SO2 Analyzer Instruction Manual, 02417, Rev. D

5.2.2.4 SO2 Cal Concentration

Before the M100AH can be spanned, it is necessary to enter the expected span concentrations for SO2. This is done by using CAL-CONC. Concentration values from 10 to 4500 PPM are accepted. If a value of XXXX is displayed, that indicates an offscale, or invalid reading. The

XXXXvalue will often be displayed at power-up when there is no data yet available to be displayed. Certain instrument fault conditions will cause X's to be displayed. This is the same as the needle being offscale on a analog meter. See the Troubleshooting Section 10.2.8 if this occurs.

5.2.2.5Formula Values

The slope and offset terms should be checked after each calibration. The values for these terms contain important information about the internal health of the analyzer.

To compute the SO2 concentration, the formula for a straight line is used.

y = mx + b

Where:

y = the SO2 concentration m = the slope

x = the conditioned PMT tube output b = the offset

In comparison with analog analyzers the slope term is equivalent to the "span pot" and the b term is equivalent to the "zero pot". Again, like an analog analyzer, there is only a limited range of adjustment allowed for either term, and there are consequences of having the values near the high or low limits of their respective ranges.

The x term is the conditioned PMT signal. PMT signal is adjusted for the lamp ratio background, range, temperature, and pressure.

The offset (b) term is the total background light with the zero term subtracted out. The zero term measures detector dark current and amplifier noise. The b term is composed mostly of the optical system background.

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