Download CSN AC 110 Esco Exam: Multiple Choice Questions and Answers and more Exams Refrigeration and Air Conditioning in PDF only on Docsity!
CSN AC 110 Esco Exam | 100% Correct
Answers | Verified | Latest 2024 Version
- Heat which causes a change in temperature of a substance is called; A. latent heat B. sensible heat C. superheat D. radiant heat - ✔✔B. sensible heat
- Heat added to a substance without a raise in temperature; (example: liquid refrigerant to gas) this process is called? A. latent heat of vaporization B. latent heat of fusion. C. superheat of vaporization D. superheat of fusion - ✔✔A. latent heat of vaporization
- Heat added to the refrigerant in a vapor state after the evaporation process is called; A. latent heat B. subcooling C. superheat D. specific heat - ✔✔C. superheat
- A scroll compressor move refrigerant by means of; A. a piston B. an impeller C. vane and cam D. involute spirals - ✔✔D. involute spirals
- The movement of heat by way of fluid (or air) is called; A. conduction B. convection C. radiation D. percussion - ✔✔B. convection
- The movement of heat through a solid object is called; A. conduction B. convection C. radiation D. compression - ✔✔A. conduction
- The standard unit for measuring the quantity of heat in a substance is; A. degrees Fahrenheit B. degrees Celsius C. degrees Rankin D. the British Thermal Unit (Btu) - ✔✔D. the British Thermal Unit (Btu)
- A refrigerant gives up heat when; A. it condenses B. it evaporates C. it is compressed D. it vaporizes - ✔✔A. it condenses
- Why must refrigerant in the suction line be slightly warmer than the saturation temperature? A. prevent liquid slugging of hte compressor B. prevent refrigerant vapor lock C. prevent the compressor from overheating
B. vaporization, expansion, condensation, compression C. compression, condensation, expansion, vaporization D. expression, compression, vaporization, condensation - ✔✔C. compression, condensation, expansion, vaporization
- If a 30 pound cylinder of reclaimed R-410A refrigerant has been stored over night at 70°F, the pressure of the cylinder shoudl be approximately: A. 201 psig B. 168 psig C. 143 psig D. 118 psig - ✔✔A. 201 psig
- Fan airflow pressures are usually measured in; A. inches of mercury vacuum or micorns B. microns or psig C. psig or inches of mercury vacuum D. inches of water column (WC) - ✔✔D. inches of water column (WC)
- Zero psia (pounds per square inch absolute) is; A. the same as atmospheric pressure B. approximately 14.7 psig at sea level C. a pressure which cannot be further reduced D. equal to 500 microns - ✔✔B. approximately 14.7 psig at sea level
- zero psig (Pounds per squeare indch gauge is; A. 25,400 microns B. approximately 29.9 psia at sea-level C. a pressure which cannot be further reduced D. the same as atmospheric pressure - ✔✔D. the same as atmospheric pressure
- The temperature at which moisture will start to condense from the air is called; A. dry bulb temperature B. wet buldb dry depression C. dew point temperature D. condensate point - ✔✔C. dew point temperature
- A compound pressure gauge measures; A. pressure and vacuum B. pressure and temperature C. pressure and humidity D. wet and dry bulb temperatures - ✔✔A. pressure and vacuum
- A mechanical shaft seal is necessary on a; A. semi-hermetic compressor B. hermetic reciprocating compressor C. hermetic rotary compressor D. open drive compressor - ✔✔C. hermetic rotary compressor
- Liquid slugging is; A. a pounding noise caused by liquid refrigerant in the suction line at the point of restriction B. noise caused by excessive liquid refrigerant in the condenser C. liquid refrigerant in the compressor clearance space D. excessive liquid refrigerant in the receiver - ✔✔C. liquid refrigerant in the compressor clearance space
- The clearance of space in a reciprocating compressor; A has no effect on compressor capacity B. has an effect on compressor capacity
- If 10LBS refrigerant pass through a water cooled condensers and lose 20 BTUs/LB of heat and 10 LBS of 80F water enter and pass through this condenser. What will the temperature of the water leaving the condenser be? A. 80°F B. 95°F C. 100°F D. 110°F - ✔✔C. 100°F
- The heat removed from the refrigerant by the condenser is; A. sensible heat only B. latent heat only C. both sensible and latent heat D. neither sensible or latent heat - ✔✔C. both sensible and latent heat
- An Energy Recovery ventilator is; A. a low ambient air temperature control B. to recover the warm air from the condenser C. a high efficient attic ventilator system D. an air to air heat-exchanger to recover heat - ✔✔D. an air to air heat-exchanger to recover heat
- When testing the efficiency of an air cooled condenser, the refrigerant condensing temperature should be approximately _____ higher than the entering air temperature? A. 30°F B. 40°F C. 100°F D. 120°F - ✔✔A. 30°F
- When testing the efficiency of a water cooled condenser, the refrigerant condensing temperature should be approximately A. 10°F
B. 30°F
C. 40°F
D. 50°F - ✔✔A. 10°F
- The first function a condenser must perform is to _______ the refrigerant before condensing can occur. A. superheat B. de-superheat C. compress D. sub-cool - ✔✔B. de-superheat
- A thermostatic expansion valve is designed to maintain; A. constant evaporator temperature B. constant refrigerant flow C. constant evaporator superheat D. constant evaporator pressure - ✔✔C. constant evaporator superheat
- The automatic expansion valve is designed to maintain; A. constant evaporator temperature B. constant refrigerant flow C. constant evaporator superheat D. constant evaporator pressure - ✔✔D. constant evaporator pressure
- The thermostatic expansion valve has three operating pressures; A. evaporator pressure, spring pressure & equalizer line pressure B. evaporator pressure, spring pressure & condensing bulb pressure C. evaporator pressure, spring pressure & liquid bulb pressure D. evaporator pressure, spring pressure & sensor bulb pressure - ✔✔D. evaporator pressure, spring pressure & sensor bulb pressure
C. flood the evaporator D. starve the evaporator - ✔✔B. close
- a rise in evaporator pressure causes the automatic expansion valve to begin to; A. open B. close C. flood the evaporator D. starve the evaporator - ✔✔A. open A thermal-electric (solid state) expansion valve is controlled by; A. suction pressure B. NTC thermistor C. thermal bulb D. external equalizing port - ✔✔B. NTC thermistor
- In a direct expansion (DX) evaporator system, the refrigerant enters the evaporator as; A. liquid only B. vapor only C. a mixture of liquid with some "flash-gas" D. superheated vapor only - ✔✔C. a mixture of liquid with some "flash-gas"
- which of the following is the most important consideration in the selection of an evaporator coil? Match the coil to the; A. sensible capacity of the condensing unit B. latent capacity fo the condensing unit C. latent capacity and outdoor design temperature D. condensing unit and the latent/sensible loads - ✔✔D. condensing unit and the latent/sensible loads
- In the evaporator;
A. latent heat is transferred form the refrigerated space to the refrigerant B. latent heat is transferred from the refrigerant to the refrigerated space C. the refrigerant changes form a vapor to a liquid D. the refrigeration system reaches its highest pressure - ✔✔A. latent heat is transferred form the refrigerated space to the refrigerant
- A liquid line filter-drier should be placed between the; A. evaporator and the compressor B. compressor and the condenser C. condenser and the metering device D. metering device and ht evaporator - ✔✔C. condenser and the metering device
- the only way to minimize flash gas is by; A. increase the superheating setting on the thermostatic expansion valve to correspond with the compressor horsepower B. change the evaporator fan to a lower setting C. sub-cooling the liquid refrigerant entering the metering device closer to the evaporator temperature D. change the evaporator fan speed to a higher setting - ✔✔C. sub-cooling the liquid refrigerant entering the metering device closer to the evaporator temperature
- A liquid receiver is used to; A prevent liquid refrigerant from reaching the compressor B. separate oil from the liquid refrigerant C. store liquid refrigerant D. receive and store vapor refrigerant - ✔✔C. store liquid refrigerant
- An accumulator is used to; A. prevent liquid refrigerant from reaching the compressor B. separate oil from the liquid refrigerant C. store liquid refrigerant
B prevent high superheat C prevent the migration of refrigerant to the compressor during the off cycle D prevent evaporator pressure from falling below a set limit - ✔✔D prevent evaporator pressure from falling below a set limit
- A liquid to suction heat exchanger is often used to. A decrease vapor super heat B increase liquid sub cooling C decrease Head pressure D increase flash gas in the suction line - ✔✔B increase liquid subcooling
- The oil pressure safety switch is operated by. A the sum of suction pressure and oil pressure B the sum of oil, pressure and crank case pressure C the difference between crank case, pressure and oil pressure D the difference between head pressure and oil pressure - ✔✔C the difference between crank case, pressure and oil pressure
- A low pressure cut off switch is used to. A establish a minimum operating pressure in the evaporator B prevent condensing pressure from reaching dangerously high levels C sense, oil pressure in the lower portion of the compressor D prevent lo oil pressure in the crank case - ✔✔A establish a minimum operating pressure in the evaporator 59.A partially iced over evaporator can be caused by. A an overcharge Be excessive airflow C. and under charge
D high indoor humidity - ✔✔C. an under charge 60 This can be used for leak detection with all high pressure refrigerants A soap bubbles B halide torch C open flame D electronic halogen detector - ✔✔A soap bubbles
- The flow rate of a TXV used in our 410 a systems as compared to R22 systems is A equal B approximately 40% to 70% higher C approximately 15% greater D approximately 15% less - ✔✔D approximately 15% less
- When using an electronic leak detector, the sensor probe. A must be moved around suspected area as fast as possible B must be exposed to a large amount of refrigerant for calibration C. should be moved at approximately 1 inch every two seconds D is not affected by dirt or oil - ✔✔C. should be moved at approximately 1 inch every two seconds
- Moisture in a refrigeration system will cars. A low head pressure B high suction pressure C evaporator icing D compressor failure - ✔✔D compressor failure
- In order to remove as much moisture as possible from a system. A flush and purge the system with liquid liquid be apply heat to the accumulator of the system
69 the R410A compound gauge reads 124 psig and the suction line temperature at the condensing unit is 54°F. What is the operating system super heat? A 96° B 30° C 12° D 6° - ✔✔C 12° 70when topping off an operating system, containing a blended refrigerant A introduce the refrigerant as a liquid into the low side, using a throttling valve B introduce the refrigerant as a vapor into the low side, using a throttling valve C. introduce the refrigerant as a liquid through the high side D weigh in the refrigerant as a vapor into the low side - ✔✔A introduce the refrigerant as a liquid into the low side, using a throttling valve
- A partially clogged capillary tube can cause. A low Head pressure B a starved condenser C a starved evaporator D a flooded evaporator - ✔✔C a starved evaporator 72 the R134A high pressure gauge reads 146 psig and the liquid line temperature at the condensing unit is 95°. What is the operating system sub cooling? A 238° B 48° C 35° D 15° - ✔✔D 15 73 an overcharge of refrigerant will cause A increased head pressure B decreased head pressure
C. bubbles in the sight glass D frost on the condenser - ✔✔A increased head pressure 74 for a customer complains that their air conditioning system is running constantly, but not cooling enough. The suction line is very cold and the compressor is sweating. The most likely cause is. A low refrigerant charge B a restriction of the return air or a dirty evaporator C high humidity conditions with a blocked condensate tube D the thermostat is set too low - ✔✔B a restriction of the return air or a dirty evaporator
- A drain trap should be installed on a split system when the. A water is recycled for green incentives B condensate line goes to an open drain C air handler drain is on the positive air D air handler drain is on the negative air side - ✔✔D air handler drain is on the negative air side
- A customer reports that their residential split system had a compressor replaced last week by another service company. Now the unit is not cooling properly. When you arrive and inspect the unit, you find that the evaporator seems to be starved for refrigerant. On examining the condensing unit, you find that the liquid line is sweating where it leaves the dryer. This is most likely the result of. A debris from the burned out compressor has clogged the dryer B air in the system C a defective replacement compressor D refrigerant overcharge - ✔✔A debris from the burned out compressor has clogged the dryer 77 what is the generally accepted range for evaporator airflow in CFM's per ton of residential air- conditioning? A 150 to 250 B 250 to 350 C 350 to 450
B a flooded evaporator C low superheat, setting D refrigerant over charged - ✔✔A that it's temperature is below the dewpoint and below 32°
- An increase in head pressure causes how much refrigerant to flow through a capillary tube. A more B less C no D the same amount of - ✔✔A more 84 with an automatic expansion valve, an increase in evaporator load will cause the A suction pressure to decrease B automatic expansion valve to close C evaporator superheat to drop D automatic expansion valve to open - ✔✔B automatic expansion valve to close
- When a TEV or a capillary tube is used as a metering device, a low refrigerant charge will cause. A high suction pressure B high head pressure C low superheat D low head pressure - ✔✔D low head pressure 86 what is the maximum operating pressure setting for an acetylene torch? A 10 psig B 15 psig C 20 psig D 25 psig - ✔✔B 15 psig
- When connecting copper to steel, the recommended braising filler alloy is a. A 45% silver alloy B copper/phosphorus alloy C 50/50 sold or alloy D 5% silver alloy - ✔✔A 45% silver alloy
- Solid contaminants, such as sludge and carbon, from a severe hermetic compressor motor burnout are best removed. A by blowing the system out with refrigerant, and then installing filter/dryers in both the liquid and suction lines B by flushing the system out, and then installing filter/dryers in both the liquid and suction lines C by blowing the system out with compressed air, and then installing filter/dryers in both the liquid and suction line D by installing filter/dryers in both the liquid and suction lines - ✔✔B by flushing the system out, and then installing filter/dryers in both the liquid and suction lines
- If the cut off plate is removed from a blower assembly, how would this affect blower performance? A it would increase airflow B it would reduce airflow C blower motor performance would increase D blower motor would operate correctly - ✔✔B it would reduce airflow 90 at a residential service call, no cooling complaint, the service technician finds the unit to be completely out of refrigerant. The technician decides to use a trace amount of refrigerant and what, in order to pressurize the system. A compressed air B oxygen C an inert gas D carbon monoxide - ✔✔C an inert gas