It is about obtaining optimum performance of plant and equipment. This can reduce running costs, avoids waste and maximises profits. Improvement in plant performance can not be gained without accurate usage data, and without calibrated instruments, retrieving base data is almost impossible. Examining any drifts in the calibration results can be the first crucial step in assessing an instruments dependability and ultimately the process stability. Accurate emission monitoring ensures compliance with local and international environmental standards and often further recognition within the marketplace.