CWS Hardness, Scale & Corrosion Control Flashcards
6 cards from real CWS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 CWS Hardness, Scale & Corrosion Control flashcards as text
What is the primary cause of scale deposits in water heaters and pipes in the US?
Answer: Calcium and magnesium carbonate precipitation
Calcium and magnesium carbonates precipitate out of hard water when heated, forming the hard scale deposits seen in water heaters and pipes.
The Langelier Saturation Index (LSI) is used to predict water's tendency to:
Answer: Form scale or corrode pipes
The LSI measures the saturation level of calcium carbonate in water; a positive value indicates scale-forming tendency and a negative value indicates corrosive tendency.
At what LSI value is water considered balanced (neither scale-forming nor corrosive)?
Answer: LSI = 0
An LSI of 0 indicates water is in equilibrium with calcium carbonate, meaning it is neither scale-forming nor corrosive.
Which water condition is most likely to cause red staining on fixtures and laundry?
Answer: High iron content
Dissolved ferrous iron oxidizes to ferric iron upon exposure to air, depositing reddish-brown stains on fixtures, laundry, and plumbing.
Galvanic corrosion in plumbing is most likely to occur when:
Answer: Two dissimilar metals are in direct contact in the presence of water
Galvanic corrosion occurs when two dissimilar metals form an electrochemical cell in the presence of an electrolyte such as water, causing the more anodic metal to corrode.
A customer reports blue-green staining on their copper fixtures. This most likely indicates:
Answer: Low pH corrosive water attacking copper pipes
Low pH (acidic) water leaches copper from pipes, and the resulting copper dissolved in water leaves characteristic blue-green stains on fixtures and sinks.