Corrosion Control Flashcards
___ is the formation on “knobs” of rust on the interior of cast iron pipes.
Tuberculation
___ has the largest impact on calcium carbonate saturation in a water supply.
pH
___ is used in water treatment and will increase the pH, hardness, and alkalinity when added.
Lime
___ ___ (sodium hexametaphosphate) is a sequestering agent used to prevent metal ions from precipitating out of solution.
sodium polyphosphate
Following the lime softening process, carbon dioxide is used to “___” and stabilize the water by reducing the pH.
“re-carbonate”
The treatment process used to control corrosion or scaling is called ___.
stabilization
Sodium bicarbonate decomposes rapidly as the temperature nears ___F so it should be stored in a cool place.
100 F
___ ___ (CaCO3) makes of the majority of scale formed on the interior walls of piping systems.
Calcium carbonate
The production of CO2 (carbon dioxide) and H2S (hydrogen sulfide) by certain bacterial organisms can ___ the rate of corrosion.
accelerate
a 50% solution of caustic soda will begin to crystalize if the temperature drops below __ F.
54 F
The Langelier Index of the raw and treated water should be calculated ___ to ensure that excessively unstable water is not being sent to customers.
daily
Excess lead and copper at the customer’s tap caused by unstable water comes from ___ ___.
household plumbing
The total alkalinity concentration should be measured every ___ ___ for operational corrosion control.
8 hours
___ and ___ are the two most active metals and are commonly used as sacrificial anodes for corrosion control.
Magnesium and zinc
It is recommended that water treatment plants always have a ___ day supply of treatment chemicals on hand to ensure potable water supply reliablitiy.
30
