Exam 3 Intro to Refrigeration
What is the acceptable filler metals for Brazing copper tubing?
A. 95% Tin - 5% Antimony B. 50% Tin - 50% Lead C. 15% to 60% Silver D. 15% to 60% Tin
What must be done before brazing a joint?
A. Clean the pipe and fitting with an abrasive. B. Make sure inside of pipe stays clean, no burrs, dirt, shavings, etc. C. Deburr both pipe and fitting. D. Fitting and pipe have the correct tolerances for brazing.
Why is the suction line insulated?
A. Helps create condensation. B. The insulation is only recommended in cold climates. C. Prevents condensation. D. Prevents the suction line from picking up excess heat.
Copper pipe used in HVAC is sized according to
A. Nom / OD B. ACR / ID C. ACR / OD D. Nom / ID
What type of piping do we use for condensate drains?
A. Type M B. Type L C. Copper D. Plastic
Cutting copper tubing is accomplished by using
A. a Tubing Cutter B. Aviation Metal Snips C. a Hacksaw D. Both A and C
An Oxygen-Acetylene or "Air-Acetylene" torch unit is most often used in the HVACR field.
True False
Joining of two pieces of copper tubing of the same diameter by expanding or stretching the end of one piece to fit over the other so that the joint may be soldered or brazed is known as Swaging
True False
The oil in a vacuum pump should be changed after each time it is used.
True False
When making a bend in soft drawn copper, you should use appropriate benders such as Spring, Lever Type, and Ratcheting or Hydraulic Type Hand benders.
True False
Unit 24 Expansion Devices
Unit 24 Expansion Devices
Unit 7 Tubing and Piping
Unit 7 Tubing and Piping
Unit 8 Leak Detection, System Evac, & System Cleanup
Unit 8 Leak Detection, System Evac, & System Cleanup
At what pressure range does the technician valve off the vacuum pump when evacuating to a deep vacuum?
a. 200 to 100 microns b. 300 to 100 microns c. 300 to 200 microns d. 500 to 250 microns
If a system with a capillary tube metering device is properly charged, when it nears the desired box temperature it will have a superheat of approximately ______.
a. 10°F to 15°F b. 2°F to 5°F c. 8°F to 12°F d. 15°F to 20°F
How many perfect threads should there typically be at the end of a threaded section of steel pipe?
a. 11 b. 5 c. 7 d. 9
A system that contains less than ______ of refrigerant does not require a leak to be repaired, but it is recommended to do so.
a. 20 lb b. 50 oz c. 15 lb d. 50 lb
A common filler material used for brazing is composed of
a. 95/5 tin-antimony. b. 15% to 60% silver. c. cast steel. d. 50/50 tin-lead.
Which of the following conditions requires a system cleanup, an oil test, and oversized filters to be added to the system?
a. A compressor motor burnout b. Noncondensables in the system c. A temperature-dependent leak in the compressor discharge line d. A vibration-dependent leak in the evaporator
Liquid, vapor, cross liquid, and cross vapor are all types of ________.
a. AXV bulb charges b. pistons c. TXV bulb charges d. capillary tube bores
Of the following heat sources, which of them burns with the hottest flame?
a. Air-acetylene torch b. Oxyacetylene torch c. Handheld MAPP gas torch d. Handheld propane torch
Moisture, acid buildup, and copper plating can all be caused by which of the following?
a. An undersized evaporator b. A clogged filter dryer c. Air in the system d. Refrigerant and oil mixing
Proper maintenance for a vacuum pump would include which of the following?
a. Changing the oil as often as necessary b. Installing a new motor on the pump c. Replacing all of the caps and plugs with new ones d. Replacing the oil sight glass
What is the most common cause of leaking compression fittings?
a. Cracked compression nut b. Pushing the tubing all the way into the fitting c. An improperly sized ring or ferrule d. Overtightening the compression nut
Which is not a pressure or force acting on a TXV diaphragm?
a. Head Pressure b. Spring pressure c. Bulb pressure d. Evaporator pressure
The size of 1/2 in. would refer to the _________ with regard to copper tubing used in plumbing and heating.
a. ID b. fitting length c. OD d. length
How does the automatic expansion valve respond to a load increase?
a. It opens, decreasing the refrigerant flow. b. It closes, decreasing the refrigerant flow. c. It opens, increasing the refrigerant flow. d. It closes, increasing the refrigerant flow.
The standard weight of copper tubing used most frequently in the heating and air-conditioning industry is
a. M. b. DWV. c. K. d. L.
Which of the tools used during the evacuation process can be wireless and use Bluetooth technology?
a. Micron gauge b. Evacuation hoses c. Vacuum pump d. Core removal tool
The size of 1/2 in. would refer to the _________ with regard to ACR copper tubing.
a. OD b. fitting length c. ID d. length
Which two types of plastic pipe can typically withstand temperatures up to 180°F?
a. PE and PVC b. ABS and PVC c. ABS and CPVC d. CPVC and PE
A system that is equipped with a _____________ may require additional steps to ensure that the entire system is evacuated.
a. TXV b. relief valve c. solenoid valve d. receiver
Which of the following statements is true regarding the flaring of copper tubing?
a. The flare nut is placed on the end of the tubing after the flare has been created. b. The flare is created by hammering the end of the soft-drawn tubing. c. The flare nut is placed on the end of the tubing before the flare has been created. d. The flare is created by extending the tubing a distance equal to the diameter of the tubing from the flaring block.
Why is a hacksaw not the preferred tool to use to cut copper tubing?
a. The hacksaw cannot get into places that a tubing cutter can. b. The hacksaw cut produces a large amount of burrs and filings. c. It takes longer to cut tubing with a hacksaw than with a tubing cutter. d. The hacksaw blade is not compatible with copper piping materials.
When a deep vacuum is reached (500 microns), the system valved and observed for 10 to 15 minutes. A rise in pressure could indicate which of the following?
a. There may be acid or sludge in the system. b. There may be a leak or the presence of air and/or moisture. c. The system charge was not properly recovered prior to evacuation. d. It is normal and does not indicate anything.
When should an externally equalized TXV be used?
a. When there is excessive pressure drop through the evaporator. b. When the system is a low- or medium-temperature application. c. When the system is equipped with a semihermetic compressor. d. When the TXV is used in a low ambient condition on a single-circuit evaporator.
To pull a vacuum means to ____.
a. allow refrigerant to escape into the atmosphere b. condense the gas in the system c. lower the pressure in a refrigeration system below atmospheric d. raise the pressure in a refrigeration system
The low-pressure side of the system must not be pressurized to more than_________ when testing for leaks.
a. atmospheric pressure b. 200 psig c. 75 psig d. the low-side design pressure
A micron gauge is used to measure ____.
a. atmospheric pressures at high altitudes b. atmospheric pressures at sea level c. high pressure in a refrigeration system d. absolute pressures below 1 mm Hg
The most important thing to keep in mind when using a press-type mechanical pipe connecting tool is to
a. avoid inserting the pipe sections completely into the fittings. b. ensure that the pipe and fittings are out-of-round to ensure a leak-free connection. c. use a hammer to ensure that the pipe sections are secure in the fittings. d. carefully read and follow all tool manufacturer's instructions.
The _____________ is both the greatest asset and the greatest liability of an electronic leak detector.
a. battery life b. range c. sensitivity d. cost
The spring-type and lever-type are two kinds of tubing
a. benders. b. cutters. c. crimpers. d. reamers.
The process of expanding one end of a section of tubing so that another section of same size tubing can be inserted into it is called
a. brazing. b. flaring. c. swaging. d. bending.
When moisture is present in a refrigeration system, it will react with the refrigerant and the oil to form ____.
a. carbon dioxide b. acid c. carbon monoxide d. carbolic acid
Steel pipe is referred to as galvanized pipe when it is
a. coated with zinc. b. coated with rust. c. painted black. d. left bare.
On a _________ TXV, the liquid pressure is cancelled out because it acts on equal areas but in opposite directions.
a. cross liquid b. cross vapor c. balanced-port d. pressure-limiting
To prevent an overloaded compressor during a hot pulldown on a low-temperature cooler, a ________ expansion valve can be used.
a. cross vapor b. balanced-port c. pressure-limiting d. cross liquid
The most accurate type of gauge for measuring a deep vacuum is a
a. digital micron gauge. b. mercury manometer. c. digital manometer. d. compound gauge
The suction line on an air-conditioning or refrigeration system is insulated to
a. encourage line sweating and prevent the absorption of additional heat. b. prevent line sweating and prevent the absorption of additional heat. c. encourage line sweating and allowing additional heat absorption. d. prevent line sweating while allowing the absorption of additional heat.
Standing, pressure-dependent, temperature-dependent, vibration-dependent, combination-dependent, and micro are all types of
a. evacuation methods. b. electronic micron gauges. c. leak methods. d. charging methods.
The bulb of the TXV is mounted on the ___________.
a. evaporator outlet b. compressor outlet c. compressor inlet d. evaporator inlet
The three factors that determine the capacity of a TXV are: evaporator temperature, liquid temperature entering the valve, and ________.
a. evaporator pressure b. pressure drop across the valve c. length of the sensing bulb transmission line d. number of evaporator circuits
Noncondensable gases ____.
a. help in pulling a vacuum b. are desirable in a refrigeration system c. are undesirable in a refrigeration system d. condense readily under normal atmospheric conditions
When checking for a leak in the evaporator coil, the leak detector can be placed
a. in the drain outlet. b. in the airstream. c. next to the evaporator fan. d. in the return duct.
A deep vacuum can most accurately be measured in
a. inches of mercury. b. pounds per square inch. c. inches of water column. d. microns.
A compound gauge ____.
a. indicates pressures above 14.696 psia b. indicates pressures in inches Hg below atmospheric pressure c. is one of two gauges on a typical gauge manifold d. all of the above
The ________ on a TXV is used to compensate for pressure drops from the inlet to the outlet of the evaporator.
a. internal equalizer b. sensing bulb and transmission line c. external equalizer d. needle and seat
All of the following statements are true regarding line sets except
a. it is illegal to manufacture precharged line sets that contain R-22. b. they must be cut and brazed into the system. c. the set consists of an uninsulated liquid line and an insulated suction line. d. they come with special quick-connect fittings.
The TXV responds to an increased heat load by __________.
a. keeping refrigerant flow constant b. not reacting to changing heat loads c. decreasing refrigerant flow d. increasing refrigerant flow
When joining sections of PVC pipe together with a union, it is always recommended to
a. leave remaining burrs in place and cement the sections together without cleaning. b. deburr the ends of the pipe and avoid using primer. c. deburr the ends of the pipe and clean the pipe and fittings with primer. d. leave remaining burrs in place and then clean the pipe and fittings with primer.
Flux is used to
a. make the filler material melt at a higher temperature. b. help prevent oxidation from forming. c. increase the rate of oxidation formation. d. make the filler material melt at a lower temperature.
The only two substances that should be circulating in a refrigeration system are
a. nitrogen and oil. b. refrigerant and oil. c. liquid and vapor. d. refrigerant and nitrogen.
Two types of evacuation methods used by technicians are
a. nitrogen sweep and standing pressure test. b. active recovery and passive recovery. c. deep vacuum and triple evacuation. d. system-dependent and self-contained.
An oily dust spot on a condenser or evaporator coil could indicate
a. noncondensables in the system. b. the presence of acid. c. a refrigerant leak. d. a defective fan motor.
The best method of leak checking is when the refrigeration system is ____.
a. operating with all fans activated b. standing with dry nitrogen pressure of 150 psig in the system c. in a vacuum d. open to the atmosphere
For black pipe sizes under 12 in., the nominal pipe size refers most closely to the
a. outside diameter of the pipe. b. length of the pipe. c. thickness of the pipe wall. d. inside diameter of the pipe.
An AXV tries to maintain a constant _________ in the evaporator.
a. pressure b. subcooling c. superheat d. frost line
On a PID controller, the difference between the superheat set point of the controller and the actual superheat is called ______.
a. proportion b. offset c. derivative d. integral
A ___________ can remove any type of foreign matter that enters a refrigeration system.
a. recovery machine b. filter drier c. vacuum pump d. compressor
Correctly installed refrigerant piping circuits help prevent
a. refrigerant loss and oil-related compressor failure. b. refrigerant loss and excess refrigerant oil in the system. c. compressor oil return and refrigerant loss. d. oil return and excess refrigerant in the system.
The _______ is located inside the valve body and moves the needle in and out of the seat in response to system load changes.
a. sensing bulb b. transmission line c. external equalizer d. diaphragm
An EEV uses a _______ to control the valve's port, which in turn controls evaporator superheat.
a. sensing bulb and transmission line b. spring c. stepper motor d. capillary tube
In order to remove moisture from a refrigeration system using a vacuum pump, it must be in a ____________state.
a. solid b. heated c. vapor d. liquid
Moisture in a liquid state must be ____ before it can be removed with a vacuum pump.
a. solidified b. cooled c. vaporized d. condensed
The needle and seat of a TXV are normally made of ________.
a. stainless steel b. aluminum c. brass d. copper
Leaks that require two or more conditions in order to induce leakage are known as
a. standing pressure leaks. b. combination-dependent leaks. c. cumulative microleaks. d. temperature-dependent leaks.
The TXV tries to maintain a constant _________ in the evaporator.
a. subcooling b. superheat c. frost line d. pressure
An evacuation process that is performed a number of times with nitrogen being used to break the vacuum, and ends with a deep vacuum is known as
a. system flush. b. nitrogen sweep. c. triple evacuation. d. refrigerant recovery.
A capillary tube metering device controls refrigerant flow by________.
a. temperature drop b. pressure drop c. using superheat d. using a stepper motor
When swaging the tubing should stick out the flaring block a distance that is approximately equal to
a. the outside diameter of the tubing plus 1/8 in. b. the radius of the tubing plus 1/4 in. c. the thickness of the tubing wall minus 1/16 in. d. the thickness of a nickel plus 1/2 in.
A large refrigeration system that contains a significant amount of moisture should be evacuated with
a. the system compressor running. b. a recovery machine then a nitrogen sweep. c. a high CFM vacuum pump. d. a low CFM vacuum pump.
The two factors that determine how much liquid will pass through a capillary tube at any given pressure drop are the _________.
a. type of refrigerant and oil b. evaporator and suction-line size c. spring and bulb pressure d. length and diameter
When leak checking the suction line with an electronic leak detector, the probe should be placed
a. under the pipe insulation. b. in the condenser air stream. c. near the receiver. d. in the evaporator air stream.
The portion of a compression fitting that actually tightens against the tubing to create the leak-free seal is the
a. union. b. ring or ferrule. c. coupling. d. compression nut.
The __________ charge bulb is usually limited to applications that have narrow operating ranges or to special functions like desuperheating on the high side of the system.
a. vapor b. cross liquid c. liquid d. cross vapor
Leaks that occur only when the unit is in operation are called
a. vibration-dependent leaks. b. temperature-dependent leaks. c. cumulative microleaks. d. combination-dependent leaks.
One of the advantages of a microfoam leak detection solution over standard bubble solutions is that it
a. will not pit or corrode the components. b. will react with refrigerant oil and become luminescent. c. contains chlorides. d. can detect leaks as small as 0.1 oz per year.
When you put the liquid line and suction line together as a pair, we refer to it as a ________ set.
line
Sludge is produced when moisture, acid, and ____________________ are present in the system.
oil