Figure 6: versus time for small-scale test with free chlorine residual adjusted to 8 mg/L. Using  mV (versus Ag-AgCl), the pit initiation time (14 days) and the relative times available for maximum (20 days) and average (74 days) pit propagation were estimated. In this test, using instead of did not change estimated initiation time and propagation rates since rose above both values between the measurements on days 11 and 14.