English to Spanish Tech/Engineering Chemistry; Chem Sci/Eng Water chemistry analyzer

The **span calibration** cycle consists of a high point calibration preceded by adjustment of the analog absorption gain for full scale input to the A/D converter. Span cal is useful if you intend to restrict the O2 measurement range to some value less than 100%. For example, if you will never measure more than 50% O2, then a span cal at 50% O2 will increase the gain of the absorption channel for additional resolution. The gain increase is limited to about double the nominal gain at 100%. There is not much improvement in the O2 noise because the noise amplitude is much larger that the converter LSB, even at low gain.