PAC 3 Test Questions & Answers

PAC 3 Test Questions & Answers In heat exchangers, which metallurgy is most prone to form waterside scale deposits? a. stainless steel b. admiralty c. mild steel d. copper - c. mild steel The localized (pitting) corrosion rate increases when: a. the cathodic area and anodic area are similar anodic area is large relitive to the cathode c. the cathodic area is large relative to the anode d. when sacrificial anodes are used - c. the cathodic area is large relative to the anode Deposits usually lead to aggravated localized corrosion because: a. decreased pH levels at the cathode b. a galvanic cell is set up between the manganese deposit and the metal c. deficient oxygen levels under the deposit d. increased pH levels at the anode e. both a and b - c. deficient oxygen levels under the deposit white rust is: a. calcium carbonate bleached by excessive chloronation b. porous zinc carbonates or zinc hydroxide corrosion product c. caused by high calcium hardness levels d. aluminum and iron corrosion product - b. porous zinc carbonates or zinc hydroxide corrosion product to prevent white rust: a. maintain alkalinity of less than 300ppm b. maintain a pH below 8.3 c. keep calcium hardness below 50ppm d. all of the above e. a and b - e. a and b chlorination of a water system with soluble iron or manganese will: a. stabilize the iron or manganese b. oxidize the iron or manganese and prevent further corrosion c. reduce the iron or manganese causing a severe corrosion potential d. oxidize the iron or manganese causing potential for fouling - d. oxidize the iron or manganese causing potential for fouling by what primary mechanism does particulate dispersant work? a. sequestation b. crystal modification c. charge reinforcement d. chelation - c. charge reinforcement In a closed system, mild steel pitting is primarily caused by: a. low levels of cathodic inhibitor b. low levels of anodic inhibitor c. loss of microbiological control d. b and c e. all of the above - e. all of the above the makeup water for a cooling water system is 100gpm and contains 150 ppm of Malk. you want to run the system at 5 cycles while maintaining 400ppm Malk int he recirc water. what 98% H2SO4 usage is required? a. 8.4 lb/day b. 1 lb/day c. 10 lb/day d. 84 lb/day e. none of the above - d. 84 lb/day The Langelier and Raznar indices are calculated from: a. solubility of CaCO3 in water b. Corrosiveness of water c. general scale tendency of water d. all of the above - a. solubility of CaCO3 in water for a clean deposit free cooling water heat exchanger, the limiting heat transfer mechanism is usually: a. conduction