CWS CWS Hardness, Scale & Corrosion Control

Question 1

What is the primary cause of scale deposits in water heaters and pipes in the US?

Accepted Answer

Calcium and magnesium carbonate precipitation

Answer

Calcium and magnesium carbonates precipitate out of hard water when heated, forming the hard scale deposits seen in water heaters and pipes.

Question 2

The Langelier Saturation Index (LSI) is used to predict water's tendency to:

Accepted Answer

Form scale or corrode pipes

Answer

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.

Question 3

At what LSI value is water considered balanced (neither scale-forming nor corrosive)?

Accepted Answer

LSI = 0

Answer

An LSI of 0 indicates water is in equilibrium with calcium carbonate, meaning it is neither scale-forming nor corrosive.

Question 4

Which water condition is most likely to cause red staining on fixtures and laundry?

Accepted Answer

High iron content

Answer

Dissolved ferrous iron oxidizes to ferric iron upon exposure to air, depositing reddish-brown stains on fixtures, laundry, and plumbing.

Question 5

Galvanic corrosion in plumbing is most likely to occur when:

Accepted Answer

Two dissimilar metals are in direct contact in the presence of water

Answer

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.

(CWS) Certified Water Specialist Practice Test

(CWS) Certified Water Specialist Practice Test

CWS CWS Hardness, Scale & Corrosion Control