Scale build-up, corrosion rate, and metal release associated with drinking water
distribution system plumbing are related to the oxidant type and concentration.
Conversely, different distribution system metals will exert different oxidant demands.
Oxidizing conditions will likely impact the nature and protective qualities of metal
corrosion byproduct scales, and metal release rates. However, the relationships are not
well understood.
The objective of this research was to study the relationship(s) among redox
potential, oxidant type, oxidant concentration, metal release rate and corrosion scale
properties of drinking water plumbing materials (copper, lead, iron, and red brass).
The research was conducted using a test loop apparatus consisting of a 100 liter
Nalgene water reservoir connected to eight parallel test loops by polyvinylchloride
(PVC) pipe. The test water reservoir had a recirculation pump system for mixing and a
separate pump system to feed test water to the loops. All pump components in contact
with the test water were constructed of metal-free materials.
Each test loop contained one approximately 480 mL sample holding cell. The
sample holding cells were equipped with ports for a pH meter and a redox potential
electrodes. Two 1"x 2"x 1/8" metal coupons with a total surface area of 9.5 in 2 yielded
a surface area to volume ratio of 0.02 in2/mL. The system simultaneously ran two sample
cells (duplicates) of each metal as an internal check of reproducibility.
Platinum combination, with silver-silver chloride reference cells, redox electrodes
have been used for in the test loop apparatus system. These redox electrodes have been
compared to known standard solutions (ZoBell's and Light's Standard solutions and the
Metrohm commercial standard solution) on an approximate biweekly basis to monitor
and ensure accurate measurements.
Includes table, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 440 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 10 |
| Published : | 11/01/2002 |
