Proceedings magazine is a communication tool for the Coast Guard's Marine Safety & Security Council. Each quarterly magazine focuses on a specific theme of interest to the marine industry.
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88 Proceedings Winter 2014 – 2015 www.uscg.mil/proceedings A nswers Engineering 1. Note: The mandatory leak repair requirements stipulate that for industrial process and commercial refrigeration CFC type equipment normally containing a refrigerant charge of 50 or more pounds (22.6 kg), leaks must be repaired if the annual leakage rate is 35% or more. These requirements may be found in 40 CFR Part 82.156. A. 15 lbs. (6.8 kg). Incorrect answer. B. 25 lbs. (11.4 kg). Incorrect answer. C. 40 lbs. (18.1 kg). Incorrect answer. D. 50 lbs. (22.6 kg). Correct answer. See Note above. 2. Note: Main condensate recirculation occurs at very low steam demands, such as while maneuvering, and is triggered by a rise in main condensate temperature. A. prevent excessive overheating of the condensate pumps. Incorrect answer. Excessive overheating of the condensate pumps is pre- vented by the main condensate pump casing continuous vent. B. balance and control condensate temper- atures at full load. Incorrect answer. Main condensate recirculation occurs at very low steam demands. C. provide adequate cooling water for the air ejector condensers. Correct answer. At low load, there would be insuffcient condensate fow to insure adequate cooling water fow for the air ejector condensers. Con- densate recirculation insures adequate cooling water fow. D. vent accumulated vapors from the con- densate pump discharge. Incorrect answer. Venting of accumulated vapors from the condensate pump discharge is accomplished by main condensate pump casing con- tinuous vent. 3. Note: Fuel combustion commences slightly after fuel injection begins and ends slightly after fuel injection ends. The delay at beginning is called the ignition delay period. The delay at ending is called the afterburning period. A. end when fuel injection has been completed. Incorrect answer. Fuel continues to burn after injection ends during the after-burning period. B. end at bottom dead center. Incorrect answer. The exhaust valves (or ports) open considerably before bottom dead center, and fuel combustion ends considerably before the exhaust valves (or ports) open. C. continue through the after-burning period. Correct answer. Fuel continues to burn after injection ends during the after-burning period. D. be completed exactly at top dead center. Incorrect answer. This is ideally true for a spark-ignition gasoline engine where the fuel burns instantaneously at top dead center, but not for a compression-ignition engine where fuel burns over a comparatively long period of piston travel after top dead center.