Q-01 FDNY Questions And Revised Correct Answers PASSED!! Rupture members, when used in parallel with a relief valve, are not to exceed _____% above designed working pressure - ANSWER : 20% Butterfly valve: where can it be used? - ANSWER : Can be used on the inlet and outlet of a water pump What electrical motor protection device automatically resets itself? - ANSWER : The thermal protector 746 watts equals how many kilowatt hours? - ANSWER : .746 kilowatt hours What position is the liquid line service valve normally in? - ANSWER : Back -seated In an operating evaporator, oil stays on top of which refrigerant? - ANSWER : Carbon dioxide, R -744 At what pressure does the relief valve blow on a high pressure machine? - ANSWER : 300 psi What would indicate a restriction (such as dirt or scale) in the liquid line? - ANSWER : Frost immediately after the restriction What does solubility mean? - ANSWER : The ability of a refrigerant to mix with other substances Charging Vapor —In a compression system, where do you charge the vapor? - ANSWER : Sucti on side of the compressor at the Suction Service Valve When comparing a brine with s PH of 8 to one with a PH of 10, its alkalinity is: - ANSWER : 100 times greater (ex. PH 8 to PH 9 is 10 times greater) In an efficiently operating induced draft cooli ng tower, the leaving water is between: - ANSWER : Dry bulb and wet bulb temperature To produce the desired evaporator temperature, the power input is reduced by keeping head pressure... - ANSWER : Head pressure as low as possible & suction pressure as high as needed The accumulator is usually between the... - ANSWER : Compressor and evaporator An oiling system in a large centrifugal system should consist of at least... - ANSWER : Reservoir, pump and distribution lines In an evaporator that chills brine, the greatest cooling effect on the brine results from the... - ANSWER : Boiling of low pressure liquid The flow of weak liquor to the absorber is controlled by A) gas pressure B) throttling device C) float valve D) pr essure of the strong liquor pump - ANSWER : B) throttling device The best way of detecting ammonia brine is by using A) CO2 gas B) potassium of lime C) Nessler reagent D) carbonate of soda - ANSWER : C) Nessler reagent The best time to purge an ammon ia plant with 250 lbs. of ammonia is A) during shut -down, because you will lose ammonia B) while charging the plant C) during operation D) none of the above - ANSWER : C) during operation What will make the strong liquor in the absorber decrease? A) exp ansion valve open too much B) A decrease in evaporator load C) An increase in evaporator load D) Too much steam on the generator - ANSWER : B) A decrease in evaporator load Which of the following statements is incorrect? A) A service valve is a key -operated shut -off valve used during shipment, installation and repairs B) Brine is a liquid cooled by refrigeration and used for the transmission of heat C) A fusible plug has a set -temperature fusible member to relieve pressure D) A rupture member automatically ruptures at a predetermined temperature - ANSWER : D) A rupture member automatically ruptures at a predetermined temperature Oil in a refrigerant should A) have a high pour point B) have a low flash point C) have a hig h viscosity D) not contain moisture - ANSWER : D) not contain moisture In an NH3 dry expansion evaporator with TXV and bulb clamped properly on the outlet of the evaporator, the superheat is A) 7 to 10° F B) 5 to 9° F C) 20 to 30° F D) 1 to 2° F - ANSW ER : A) 7 to 10° F The setting of a fusible plug is A) 280° F B) 300° F C) 380° F D) 300 psig. - ANSWER : A) 280° F If the insulation was removed from the bulb of the expansion valve, what would happen? - ANSWER : Flooded evaporator —
the TXV bulb ope ns in a range from 45 to 85° F. If the insulation was removed, the bulb would sense the temperature in the machine room and keep the TXV open, thus flooding the evaporator. On the most common three -phase, four -wire service, the voltage between any phase and neutral should be A) 105 volts B) 120 volts C) 208 volts D) 220 volts - ANSWER : B) 120 volts A refrigerant overcharge would A) increase head pressure B) decrease head pressure C) decrease solution -side pressure D) decrease discharge -side pressure - ANSWER : A) increase head pressure
the TXV bulb ope ns in a range from 45 to 85° F. If the insulation was removed, the bulb would sense the temperature in the machine room and keep the TXV open, thus flooding the evaporator. On the most common three -phase, four -wire service, the voltage between any phase and neutral should be A) 105 volts B) 120 volts C) 208 volts D) 220 volts - ANSWER : B) 120 volts A refrigerant overcharge would A) increase head pressure B) decrease head pressure C) decrease solution -side pressure D) decrease discharge -side pressure - ANSWER : A) increase head pressure
