Water Treatment Flashcards
In cooling towers, heavy metals, oxidizing chemicals, and non-oxidizing chemicals are used to:
Select one:
a. Inhibit corrosion
b. Inhibit biological fouling
c. Eliminate wood deterioration
d. Reduce scaling
b. Inhibit biological fouling
External deaeration:
Select one:
a. Removes dissolved gases from the water
b. Relies entirely on the addition of chemicals
c. Removes all dissolved gases and solids from the water
d. Only removes oxygen from the water
a. Removes dissolved gases from the water
Scaling is not as severe in cooling towers when compared to boilers because:
Select one:
a. Cooling towers evaporate less water
b. There are not as many dissolved solids in cooling tower water
c. Water temperatures are not as high in cooling towers as they are in boilers
d. Cooling tower water is constantly being aerated
c. Water temperatures are not as high in cooling towers as they are in boilers
To prevent scale formation, \_\_\_\_\_\_\_\_ is added to the boiler water. Select one: a. Zeolite b. Sodium chloride c. Amine d. Phosphate
d. Phosphate
In a galvanic corrosion cell, the metal that corrodes is the
Select one:
a. anode
b. cathode
c. noble metal
d. metal with the more positive electrochemical potential
a. anode
Water filters must be cleaned: Select one: a. If the water becomes hard b. When the dissolved solids are high c. By backwashing the filter media d. By chemically cleaning the filter media
c. By backwashing the filter media
Which of the following is an example of a dissolved solid? Select one: a. Magnesium sulphate b. Oxygen c. Sand d. Carbon dioxide
a. Magnesium sulphate
Materials which are generally larger than 2 micrometres and that are dispersed throughout the water, are called: Select one: a. Dissolved solids b. Colloidal particles c. Suspended matter d. Dissolved matter
c. Suspended matter
In cooling towers, sacrificial anodes work by
Select one:
a. plating the metal parts with non-corrosive metal ions.
b. neutralizing acidic compounds.
c. corroding, instead of the metal cooling tower parts
d. interfering with the formation of corrosive reaction products.
c. corroding, instead of the metal cooling tower parts
Suspended matter must be removed from feedwater to:
Select one:
a. Prevent overheating of the boiler metal
b. Prevent boiler waterside scale deposits
c. Reduce the alkalinity of the water
d. Eliminate the hardness of the water
Prevent overheating of the boiler metal
To minimize galvanic corrosion
Select one:
a. Use only noble metals.
b. A sacrificial anode may be installed to protect the cathodic materials.
c. If dissimilar metals are used, they must be directly connected to each other.
d. The electrochemical potential difference between any two connected materials must be greater than 0.15 V.
b. A sacrificial anode may be installed to protect the cathodic materials.
Galvanic corrosion depends on
Select one:
a. how fast the electrons flow through the electrolyte.
b. the difference in mass between the two inter-connecting metals.
c. the size of the sacrificial anode.
d. a difference in electrochemical potential between dissimilar metals.
d. a difference in electrochemical potential between dissimilar metals.
When only one specific type of metal is subject to corrosive attack, the corrosion process is called:
Select one:
a. cathodic corrosion
b. galvanic corrosion
c. selective leaching
d. anodic corrosion
c. selective leaching
Oxygen in condensate can cause:
Select one:
a. highly acidic water
b. low alkalinity
c. scale deposition
d. pitting corrosion
d. pitting corrosion
By definition, alum, when added to water to form floc in a clarifying system, is known as a: Select one: a. Curdler b. Congealant c. Coagulant d. Flocculant
d. Flocculant
The principal cause of steel corrosion in cooling towers is: Select one: a. Dissolved carbon dioxide b. High pH c. Dissolved oxygen d. Low pH
c. Dissolved oxygen
Where does the carbonic acid found in condensate come from?
Select one:
a. From the decomposition of dissolved carbonates and bicarbonates in the boiler water.
b. From inorganic compounds that enter through leaking heat exchangers.
c. From under-feeding oxygen scavengers to the boiler drum.
d. From the oxidation of carbon steel condensate piping.
a. From the decomposition of dissolved carbonates and bicarbonates in the boiler water.
Chillers must have _____________ to protect the evaporator coil from freezing damage.
Select one:
a. heaters
b. anti-freeze
c. frost plugs
d. freeze stats
d. freeze stats
In a steam plant, condensate treatment is necessary
Select one:
a. to provide clean, potable drinking water.
b. because condensate can contain impurities harmful to boilers and condensate return systems.
c. to provide ultra-pure boiler feedwater.
d. to aerate the condensate before it enters the deaerator.
b. because condensate can contain impurities harmful to boilers and condensate return systems.
Sludge conditioning in a boiler:
Select one:
a. Is controlled by the continuous blowdown
b. Prevents pollution from the blowdown water
c. Prevents precipitates from adhering to boiler surfaces
d. Is done to mix the sludge with the boiler water
c. Prevents precipitates from adhering to boiler surfaces
Direct measurement of condensate amine can be done using:
Select one:
a. a coupon rack
b. methyl purple and sulfuric acid
c. a chromatograph or a fluorometer
d. a commercially available iron analysis kit
c. a chromatograph or a fluorometer
When testing boiler water, a conductivity meter is used to measure:
Select one:
a. Total alkalinity
b. Hardness in parts per million or grains per gallon
c. Total suspended matter
d. Total dissolved solids
d. Total dissolved solids
What checks should be done yearly on heating or cooling systems that contain glycol?
Select one:
a. check for increasing pH and dissolved carbon dioxide
b. check toxicity and specific heat
c. check for viscosity and pour point
d. check for freeze point and inhibitor strength
d. check for freeze point and inhibitor strength
Condensate return line corrosion can be controlled by:
Select one:
a. Feeding sodium bicarbonate to the boiler
b. Adding sodium sulfite
c. Feeding amines
d. Adding polymers
c. Feeding amines
Phenolphthalein:
Select one:
a. Turns pink in the presence of hydroxide and carbonate alkalinity
b. Is fed to cast iron boilers
c. Prevents caustic embrittlement
d. Indicates the presence of dissolved oxygen
a. Turns pink in the presence of hydroxide and carbonate alkalinity
The wood used in cooling towers contains natural compounds called __________, that resist decay.
Select one:
a. celluloses
b. biocides
c. extractives
d. lignins
c. extractives
Coagulants, when added to water: Select one: a. Soften the water b. Will help remove fine particles c. Remove the dissolved solids d. Cause fine particles to float to the surface
b. Will help remove fine particles
During the “Rinse” stage when regenerating a sodium zeolite softener, the solution going to the sewer contains: Select one: a. Calcium sulphate b. Sulphates and bicarbonates c. Calcium and magnesium ions d. Sodium bicarbonates and sulphates
c. Calcium and magnesium ions
Sodium zeolite softeners:
Select one:
a. Remove all dissolved solids and suspended matter from the water
b. Remove calcium and magnesium ions from the water
c. Are regenerated with an acid solution
d. Remove all dissolved solids from the water
b. Remove calcium and magnesium ions from the water
Dezincification is a form of
Select one:
a. under-deposit corrosion
b. dielectric corrosion
c. selective leaching
d. stress corrosion cracking
c. selective leaching
Which of the following is NOT a cause of, or a factor in, closed loop system corrosion?
Select one:
a. low pH
b. galvanic action
c. dissolved oxygen
d. caustic gouging
d. caustic gouging
Caustic embrittlement of boiler metal is promoted by: Select one: a. Concentrations of sodium hydroxide b. Concentration of sodium chloride c. Overheating of boiler parts d. Concentration of sodium sulfite
a. Concentrations of sodium hydroxide