31
Figure 5. Temperature Compensated Element
The resistance of both the exposed element (R
Exp
) and reference element (R
Ref
) are equally influenced by
temperature. Consequently, the resistance ratio of the exposed to reference elements is a function only
of the loss in metal thickness on the exposed element, and therefore of corrosion.
This resistance ratio (R
Exp
/ R
Ref
) is measured either periodically with a portable instrument, or continu-
ously with a variety of continuous, automatic recording/data logging instruments and read as percentage
thickness loss. Thus, total metal loss versus time is directly available, and corrosion rate is indirectly
available as the slope of the line for metal loss versus time.
Figure 6. Typical Data