Unit6 Water Treatment Flashcards
(88 cards)
Carbon dioxide may cause corrosion in condensate return lines. This corrosive carbon dioxide may originate:
Select one:
a. by absorption in the deaerator
b. as sodium sulfite in the boiler water
c. by decomposition of bicarbonates in the boiler water
d. In condensate neutralizing amines
c. by decomposition of bicarbonates in the boiler water
When only one specific type of metal is subject to corrosive attack, the corrosion process is called:
Select one:
a. anodic corrosion
b. cathodic corrosion
c. selective leaching
d. galvanic corrosion
c. selective leaching
The main scale forming substance in cooling water towers is: Select one: a. Magnesium carbonate b. Sodium sulfite c. Calcium bicarbonate d. Sodium phosphate
c. Calcium bicarbonate
Sludge is usually removed from a boiler by:
Select one:
a. Filtering the water before it leaves the boiler
b. Vacuuming it from the bottom
c. Blowing off through the bottom blowoff connection
d. Blowing down through the continuous blowdown
c. Blowing off through the bottom blowoff connection
Sodium sulfite:
Select one:
a. Prevents the corrosion caused by oxygen in boiler water
b. Precipitates calcium and magnesium compounds
c. Prevents scale adhering to the tubes
d. Controls foaming
a. Prevents the corrosion caused by oxygen in boiler water
Direct measurement of condensate amine can be done using:
Select one:
a. a commercially available iron analysis kit.
b. methyl purple and sulfuric acid
c. a chromatograph or a fluorometer
d. a coupon rack
c. a chromatograph or a fluorometer
To minimize galvanic corrosion
Select one:
a. If dissimilar metals are used, they must be directly connected to each other.
b. The electrochemical potential difference between any two connected materials must be greater than 0.15 V.
c. Use only noble metals.
d. A sacrificial anode may be installed to protect the cathodic materials.
d. A sacrificial anode may be installed to protect the cathodic materials.
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
The wood used in cooling towers contains natural compounds called __________, that resist decay.
Select one:
a. extractives
b. celluloses
c. lignins
d. biocides
a. extractives
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
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 for viscosity and pour point
c. check toxicity and specific heat
d. check for freeze point and inhibitor strength
d. check for freeze point and inhibitor strength
In condenser cooling water systems, sacrificial anodes work by
Select one:
a. neutralizing acidic compounds.
b. plating other metal parts with non-corrosive metal ions.
c. interfering with the formation of corrosion products in a corrosion cell reaction.
d. corroding preferentially over components made of other metals.
d. corroding preferentially over components made of other metals.
What is the purpose of corrosion coupons?
Select one:
a. They are used to prevent galvanic corrosion
b. They attract corrosion products and keep them from depositing in the condensate system.
c. They detect the presence of corrosive non-condensable gases.
d. They are used to determine corrosion rates
d. They are used to determine corrosion rates
A conductivity meter is used to measure the: Select one: a. Alkalinity b. Electrolyte c. Hardness d. Total Dissolved Solids
d. Total Dissolved Solids
If heating or cooling system water may come into contact with food products, ___________ is used to keep the water from freezing.
Select one:
a. octyl alcohol
b. ethylene glycol
c. propylene glycol
d. methanol
c. propylene glycol
If flow is too high, the resin in a sodium zeolite softener may be discharged to sewer during the \_\_\_\_\_\_\_\_\_ stage. Select one: a. Service b. Slow rinse c. Fast rinse d. Backwash
d. Backwash
Boiler water that is too alkaline will likely:
Select one:
a. Produce scale inside the boiler
b. Have a low pH
c. Cause foaming in the boiler
d. Cause grooving on a boiler’s waterside surfaces
c. Cause foaming in the boiler
Where does the carbonic acid found in condensate come from?
Select one:
a. From inorganic compounds that enter through leaking heat exchangers.
b. From under-feeding oxygen scavengers to the boiler drum.
c. From the oxidation of carbon steel condensate piping.
d. From the decomposition of dissolved carbonates and bicarbonates in the boiler water.
d. From the decomposition of dissolved carbonates and bicarbonates in the boiler water.
Grooving and general thinning of the condensate return system is a result of:
Select one:
a. oxygen corrosion
b. scale build-up
c. carbonic acid corrosion
d. high alkalinity
c. carbonic acid corrosion
How does one type of amine protect a condensate system?
Select one:
a. By forming a protective film coating on scale forming solids
b. By neutralizing carbonic acid
c. By scavenging oxygen from the condensate
d. By neutralizing hydroxide alkalinity
b. By neutralizing carbonic acid
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
Total alkalinity is measured:
Select one:
a. Using methyl purple indicator and sulfuric acid
b. Using potassium iodide-iodate and EDTA
c. To control the concentration of oxygen scavenger
d. Using phenolphthalein and sulfuric acid
d. Using phenolphthalein and sulfuric acid
In cooling towers, sacrificial anodes work by
Select one:
a. plating the metal parts with non-corrosive metal ions.
b. corroding, instead of the metal cooling tower parts
c. neutralizing acidic compounds.
d. interfering with the formation of corrosive reaction products.
b. corroding, instead of the metal cooling tower parts
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