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All Textbook Solutions for Refrigeration and Air Conditioning Technology (MindTap Course List)
Temperature is defined as A. how hot it is. B. the level of heat. C. how cold it is. D. why it is hot.State the standard conditions for water to boil at 212F.List four types of temperature scales.Under standard conditions, water freezes at ____C.Molecular motion stops at _______F.One British thermal unit will raise the temperature of _____ 1b of water _____F.In which direction does heat flow? A. From a cold substance to a cold substance B. Up C. Down D. From a warm substance to a cold substanceDescribe heat transfer by conduction.Increase in sensible heat causes A. a higher thermometer reading. B. a lower thermometer reading. C. no change of the thermometer reading. D. ice to melt.Latent heat causes A. a higher thermometer reading. B. temperature to rise. C. a change of state. D. temperature to fall.Describe how heat is transferred by convection.Describe how heat is transferred by radiation.Specific heat is the amount of heat necessary to raise the temperature of 1 lb of a ______1F.Atmospheric pressure at sea level under standard conditions is ______inches of mercury (Hg) or_____ pounds per square inch absolute (psia).To change from psig to psia, you must add _______to psig.Convert 80F of Celsius.Convert 22C to Fahrenheit.Matter is a substance that occupies space and has A. color. B. texture. C. temperature. D. mass.What are the three states in which matter is commonly found?________ is the term used for water when it is in the solid state.In what direction does a solid exert force?In what direction does a liquid exert force?Vapor exerts pressure in what direction? A. Outward B. Upward C. Downward D. All of the aboveDefine density.Define specific gravity.Describe specific volume.Why does an object weigh less on the moon than on earth?The density of tungsten is 1210 lb/ft3. What would be its specific volume?The specific volume of red brass is 0.001865 ft3/lb. Whatwould be its density?Aluminum has a density of 171 lb/ft3. What would be its specific gravity?Four pounds of a gas occupy 10 ft3. What would be itsdensity and specific gravity?Why is information regarding the specific volume of gases important to the designer of air-conditioning, heating, and refrigeration equipment?Whose law states that the volume of a gas varies inversely with the absolute pressure, as long as the temperature remains constant? A. Charles' B. Boyle's C. Newton's D. Dalton'sAt a constant pressure, how does a volume of gas vary with respect to the absolute temperature?Describe Dalton's law as it relates to a confined mixture of non-reactive gases.What are the two types of energy most frequently used or considered in this industry?How were fossil fuels formed?21RQ22RQIf an air-conditioning compressor weighing 300lb had tobe lifted 4 ft to be mounted on a base, how much work, in ft-lb. must be done?Describe horsepower and list the three quantities needed to determine horsepower.How many watts of electrical energy are equal to 1 hp?How many Btu of heat can be produced by 4 kWh ofelectricity?How many Btu/h would be produced in a 12-kW electricheater?What unit of energy does the power company charge the consumer for?If 3000 ft3 of air is crossing an evaporator coil and iscooled from 75F to 55F, what would be the volume of air, in ft3, exiting the evaporator coil?A gas is compressed inside a compressor's cylinder. When the piston is at its bottom dead center, the gas is initially at 10 psig, 65F, and 10.5 in3. After compression and when the piston is at top dead center, the gas is 180Fand occupies 1.5 in3. What would be the new pressure of the gas in psig?Name three reasons why ice melts in an icebox: _______, __________, ________.What are the approximate temperature ranges tor low-, medium-, and high-temperature refrigeration applications?One ton of refrigeration is A. 1200 Btu. B. 12,000 Btu/h. C. 120,000 Btu. D. 120,000 Btu/h.Describe briefly the basic refrigeration cycle.What is the relationship between pressure and the boiling point of liquids?What is the function of the evaporator in a refrigeration or air-conditioning system?What does the compressor do in the refrigeration system?Define a superheated vapor.The evaporating pressure is 76 psig for R-22 and the evaporator outlet temperature is 58F. What is the evaporator superheat for this system? A. 13F B. 74F C. 18F D. 17FIf the evaporating pressure was 76 psig for R-22 and the compressor inlet temperature was 65F, what would be the total superheat entering the compressor? A. 11F B. 21F C. 10F D. 20FDefine the term subcooled liquid.The condensing pressure is 260 psig and the condenser outlet temperature is 108F for R-22. By how many degrees is the liquid subcooled in the condenser? A. 12F B. 42F C. 7F D. 14FThe condensing pressure is 260 psig and the meteringdevice inlet temperature is 100F for R-22. What is the total subcooling in this system? A. 15F B. 20F C. 25F D. 30FWhat is meant by a saturated liquid and vapor?What is meant by desuperheating a vapor?What happens to the refrigerant in the condenser?What happens to refrigerant heat in the condenser?The metering device A. cycles the compressor. B. controls subcooling. C. stores refrigerant. D. meters refrigerant.What is adiabatic expansion?Describe flash gas, and tell how it affects systemcapacity.Quality means _________ when referring to a refrigerant.Describe the difference between a reciprocating compressor and a rotary compressor.List the cylinder color codes for R-12, R-22, R-502, R-134a, R-11, R-401A, R-402B, R-410A, R-404A, andR-407C.Define enthalpy.Define a pure compound refrigerant, and give two examples.Define net refrigeration effect as it applies to the refrigeration cycle.Define heat of compression, and explain how it is computed.Define flash gas, and explain how it applies to the net refrigeration effect of the refrigeration cycle.Define temperature glide as it pertains to a refrigerant blend.Define a zeotropic refrigerant blend, and give an example.Define a near-azeotropic refrigerant blend, and give twoexamples.Where would a technician encounter freezing temperatures when working with liquid refrigerant?Which of the following can happen to a full nitrogen cylinder when the top is broken off? A. Nitrogen will slowly leak out. B. There will be a loud bang. C. The tank will act like a rocket and move very fast. D. It will make a sound like a washing machine.Why must nitrogen be used only with a regulator when it is charged into a system?What can happen when oil is mixed with oxygen under pressure?Trying to stop escaping liquid refrigerant with your hands will result in ______.Electrical shock to the body affects the _____.Electrical energy passing through the body causes two types of injury, ______and _____.How can a technician prevent burning the surroundings while soldering in a tight area?What safety precautions should be taken when starting a large electric motor whose coupling is disconnected?The third (green) wire on an electric drill is the ______ wire.11RQ12RQWhen a hermetic motor burns while in use,________are produced.What refrigerant safety group classification has the highest flammability and the highest toxicity?What do the letters A, B, and C mean on a fire extinguisher?_________and _________are two types of screwdriver bits.Five different types of wrenches are_____,_____, _______, and _________.Give an examples of a use for a nut driver.List four different types of pliers.Describe two types of benders for soft tubing.A wiring and crimping tool is used to A. crimp tubing. B. assemble tubing. C. cut and strip wire. D. install wire staples.A flaring tool is used to A. cut copper tubing. B. flare a sheet metal joint. C. put a flare on the end of copper tubing. D. provide a yoke for bending brazing filler metal.A vacuum pump is used to A. remove contaminants from a refrigeration system. B. vacuum dust before installing the refrigeration system compressor. C. vacuum the area before using an air-acetylene unit. D. prepare an area for taking a temperature reading.Two types of refrigerant leak detectors are ______and_____.List the components usually associated with a gauge manifold unit.List three types of thermometers.For what type of soldering is a soldering gun normally used?An air-acetylene unit is used for _______ and _______.14RQWhen are air velocity measuring instruments used?Describe the purpose of CO2 and O2 indicators.What is the purpose of a draft gauge?18RQWhy would a technician use an electronic charging scale?Why is it necessary to recover refrigerant?Three types of nails are _______, ________, and _____.The term _________is used to indicate the size of acommon nail.What is the abbreviation for the answer to question 2?An outward clinch tacker is used to A. bend wire on a pipe hook. B. install a pin rivet. C. drive roofing nails. D. spread the ends of a staple outward.Wood screws generally have A. a flat head. B. a round head. C. an oval head. D. any of the above.List and describe three methods of securing an object to a wall made of gypsum board.7RQ8RQ9RQWrite a typical dimension for a tapping screw. Explaineach part of the dimension.11RQ12RQDescribe the procedure for fastening two pieces of sheet metal to ether with a tapping screw.Hollow rivets are assembled in a pin that is often called A. a mandrel. B. a nozzle. C. an anchor. D. a clinch.15RQ16RQ17RQ18RQExplain the purpose of external and internal retaining clips.20RQThe standard weight of copper tubing used most frequently in the heating and air-conditioning industry is A. K. B. L. C. DWV. D. M.The size of 1/2 in. would refer to the ______regard to copper tubing used in plumbing and heating. A. ID B. OD C. length D. fitting lengthThe size of 1/2 in. would refer to the _______ with regard to ACR copper tubing. A. ID B. OD C. length D. fitting lengthIn what size rolls is soft copper tubing normally available?Why are some ACR tubing lines insulated?Describe procedures for bending soft copper tubing.Describe the procedure for cutting tubing with a tube cutter.What type of solder is suitable for moderate temperatures and pressures?Describe the steps for making a good soldered copper tubing/fitting joint.Describe the procedures for making a flare for joining copper tubing.The portion of a compression fitting that actually tightens against the tubing to create the leak-free seal is the A. union. B. coupling. C. compression nut. D. ring or ferrule.What is the most common cause of leaking compression fittings? A. Cracked compression nut B. Overtightening the compression nut C. An improperly sized ring or ferrule D. Both A and C are common causes of fitting leakageA common filler material used for brazing is composed of A. 50/50 tin-lead. B. 95/5 tin—antimony. C. 15% to 60% silver. D. cast steel.When soldering, a flux is used to A. minimize oxidation while the joint is being heated. B. allow the fitting to fit easily onto the tubing. C. keep the filler metal from dropping on the floor. D. help the tubing and fitting to heat faster.List the procedures used when setting up, igniting, and using an air-acetylene unit.Describe the procedure for preparing and threading the end of steel pipe.Describe each part of the thread dimension 1/4-18 NPT.The low-pressure side of the system must not be pressurized to more than A. 75 psig. B. 200 psig. C. the low-side design pressure. D. atmospheric pressure.Name and briefly describe the six classes of leaks.The ________is both the greatest asset and the greatest liability of an electronic leak detector.Why should oxygen or compressed air never be used pressurize a system?List some of the foreign matter that may enter a refrigeration system.True or False: A vacuum pump can remove any type of foreign matter that enters a refrigeration system.Air in a refrigeration system causes which of the following problems? A. Acid buildup B. Moisture C. Copper plating D. All of the aboveThe only two products that should be circulating in a refrigeration system are _____and____.In order to remove moisture from a refrigeration system using a vacuum pump, it must be in a _____state.Are the best vacuum pumps one-stage or two-stage?Name the two types of vacuum procedures used by technicians.What can be done to get water out from under the oil level in a compressor?When evacuating a refrigeration system that has solenoid valves, what special procedure must be followed?What is today's most accurate type of deep vacuum gauge?_________microns are in 1 inch.Briefly describe the method for cleaning up a system that has experienced a motor burn.What is the advantage of using large gauge lines for evacuation?Why is it important to change the oil on a vacuum pump after each evacuation?Describe the meaning of a deep vacuum, and explain why it is important to reach and hold a deep vacuum when pulling a vacuum on a system.List the main advantages of a microfoam leak detectionsolution over standard bubble solutions.What could an oily dust spot on a condenser or evaporator coil indicate?Why should a condenser be covered with a sheet before leak checking it with an electronic detector?Leaks that occur only when the unit is in operation are called ______dependent leaks.Briefly describe a combination-dependent leak.What is the difference between the oxygen we breathe and the ozone located in the earth's stratosphere?Describe the difference between good and bad ozone.Explain the process of ozone depletion resulting from the breaking up of a CFC molecule in the stratosphere.Which refrigerants have a 0 ODP? A. HFCs B. HCFCs C. CFCs D. Both A and BAn increase in the natural greenhouse effect that leads to heating of the earth is called _____.True or False: Only CFCs and HCFCs contribute toglobal warming.Explain what a global warming potential (GWP) is.8RQDescribe the difference a direct and an indirect global warming potential.What measurement or index takes into considerationboth the indirect and direct global warming effects of refrigerants? A. Total equivalent warming impact (TEWI) B. Greenhouse effect number C. Global warming number D. Greenhouse effect indexDescribe the differences between CFCs, HCFCs, HFCs,and HCs.CFCs are more harmful to the stratospheric ozone layer than HCFCs because they contain _____.13RQDescribe the difference between an azeotropic refrigerant blend and a near-azeotropic or zeotropic refrigerant blend.Why are there more safety precautions for R-410A than with other popular refrigerants like R-22 and R-404A?The three most popular synthetic oils in the refrigeration and air-conditioning industry are _______, ________, and ______.What is the name of the conference that was held in Canada in 1987 to attempt to solve the problem of refrigerants released into the atmosphere?What agency ofthe federal government is charged withimplementing the United States Clean Air Act Amendments of 1990?Explain the differences between active and passive recovery methods.Are federal excise taxes on reclaimed refrigerants the same as those for new refrigerants?21RQ22RQTo reclaim refrigerant meas to__________.Explain what is meant by a nonpressurized recovery container, and briefly explain which applications it is used for.25RQ26RQThe standard that a refrigerant must meet after it has been reclaimed and before it can be sold to another owner is A. ANSI 7000. B. ANSI 700. C. EPA 7000. D. AHRI 700.Briefly describe the types of piercing valves used in the industry, and list some advantages and disadvantages of both.Briefly describe an oil-less refrigerant recovery unit.How can liquid refrigerant be added to the refrigeration system when the system is out of refrigerant?How is the refrigerant cylinder pressure kept above the system pressure when a system is being charged with vapor from a cylinder?Why does the refrigerant pressure decrease in a refrigerant cylinder while charging with vapor?What type of equipment normally has the refrigerantcharge printed on the nameplate?Why are digital scales preferred over other types for charging refrigeration and air-conditioning systems?How does a graduated cylinder account for the volume change due to temperature changes?What methods besides weighing and measuring are used for charging systems?Two or more refrigerants combined together to createanother refrigerant is referred to as a(n) ________.Define temperature glide, and give examples of where it occurs in a refrigeration system.A portion of a refrigerant blend that is evaporating or condensing before the rest of the same blend is called__________.What is the main difference between a zeotropic and an azeotropic refrigerant blend?What is meant by "restricting" liquid refrigerant into a refrigeration system when charging?What causes fractionation in certain refrigerant blends?When should a service technician use the subcooling method of charging air-conditioning and heat pump systems?A service technician is charging an air-conditioning system that has a TX V as the metering device using the subcooling method of charging. The high-side saturation temperature is 110F and the unit's technical manual specifies 10F of liquid subcooling. What would thedesired liquid-line temperature be at the condensing unit?A technician takes the following readings on an R-404A refrigeration system: Head pressure = 205 psig Suction pressure = 30 psig Condenser outlet temperature = 80F Evaporator outlet temperature = 10F Using the pressure/temperature chart in Figure 10.25, find the condenser subcooling and evaporator superheat amounts.What does "calibrating an instrument" mean?Three reference points that may be used to check temperature-measuring instruments are_________, _______, and______.3RQTemperature-measuring instruments may be designed to measure the temperature of vapors, ________, and________.Glass stem thermometers are being replaced by __________thermometers.True or False: To check the temperature leads of an electronic thermometer for low temperatures, they should be stirred in a container of crushed ice, water, and a table-spoon of salt.Accuracy of a thermometer is more important in the ______temperature ranges.8RQ9RQWhat should a gauge manifold reading indicate when opened to the atmosphere?Describe how the ohmmeter feature of a VOM can be checked.12RQ13RQWhat are three instruments that a flue-gas analysis kit might contain?The __________is that part of an atom that moves from one atom to another. A. electron B. proton C. neutronWhen this part of an atom moves to another atom, the losing atom will have a ______charge. A. negative B. positive C. neutralState the differences between AC and DC.Describe how a meter would be connected in a circuit to measure the potential difference across a light bulb.Describe how an amperage reading would be taken using a clamp-on or clamp-around ammeter.Describe how the total resistance in a series circuit is determined.Ohm's law for determining voltage is _______.Ohm's law for determining amperage is_________.Ohm's law for determining resistance is_______.10RQDescribe the characteristics of the voltage, amperage, and resistances when there is more than one load in a parallel circuit.If there were a current flowing of 5A in a 120-V circuit,what would the resistance be? A. 25 B. 24 c. 600 D. 624If the resistance in a 120-V circuit was 40 , what would the current be in amperes? A. 4800A B. 48A C. 4A D. 3AElectrical power is measured in A. amperes. B. volts. C. watts. D. ohms.The formula for determining electrical power is______.Describe how a step-down transformer differs from a step-up transformer.What are the three types of opposition to current flow that impedance represents?18RQWhat does forward bias on a diode mean?The unit of measurement for the charge a capacitor can store is the A. inductive reactance. B. microfarad. C. ohm. D. joule.What is the device that consists of two unlike metal strips that are attached and have a different rate of expansion and contraction? A. Thermistor B. Thermocouple C. Diaphragm D. BimetalWhat are some application of the bimetal strip?How can the bimetal strip be extended to have more travel per degree of temperature change?What two metals can be used in the bimetal device or the rod and tube?A thin, flexible metal disc with a large surface area is a ______.6RQWhat is the difference between a bellows and a diaphragm?Which type of fluid is normally found in a belloows?Which of the following is a device consisting of two unlike metals fastened at one end that, when heated on the fastened end, produces a DC current? A. Thermocouple B. Thermistor C. Diaphragm D. BimetalHow can a thermocouple be used to verify that a gas flame is present?11RQ12RQ13RQDraw and explain how a PTC thermistor assists with increasing the starting torque of a motor.Why is a low-voltage thermostat normally more accurate than a high-voltage thermostat?The three kinds of switching mechanism used in low-voltage thermostats are____, _______, and ________.3RQWhat does a cold anticipator do?Define system overshoot when dealing with theromostats.6RQ7RQDescribe the method a service technician should follow when measuring the current that normally travels through a heating anticipator.Explain how microelectromc or electrontc thermostats handle system overshoot and system lag.10RQWhat component steps down the voltage to the low-voltage value?Low voltage is desirable for residential control voltages because of _______, _______, _______, and ______.What is the maximum amperage usually encountered by a low-voltage thermostat?14RQ15RQWhat two types of switches are normally found in the subbase of a low-voltage thermostat?17RQ18RQWhy is a line-voltage thermostat mounted on an electrical box that has conduit connected to it?What is the principle of operation for most externally mounted overload protection devices?Describe a method for speedmg up the cooling of an open motor.Describe two methods for cooling an overheated compressor.How can an electronic thermometer be used in a well to obtain an accurate response?A temperature-sensing device used in measuring airflow is the_______.How does a thermocouple change with a temperature change?True or False: Pressures below atmospheric pressure cannot be detected.Name one function of the low-pressure control.Which is true of a high-pressure control? A. It closes on a rise in pressure. B. It opens on a fall in pressure. C. It is located on the evaporator. D. It protects the compressor from pressures.Name two types of water pressure control.Why should a safety control not be adjusted if it has a seal to prevent tampering?31RQTrue or False: A change in the differential setting will automatically change the cut-in point of the control.True or False: A change in the differential of a control will always change the range of the control.