Refrigeration & AC

When repairing a refrigeration system, a swaging tool set would be used to carry out which of the following operations?

In a refrigeration system that is not protected by a water failure switch, if the cooling water to the condenser fails, what will be the result for protective purposes?

When the relief valve opens on a refrigeration compressor discharge line, it discharges high-pressure refrigerant vapor to what location?

The rupture disc on a low-pressure centrifugal refrigeration unit is used as an overpressure protection device and is set to relieve at 15 psig and is most likely to lift when the compressor is idle. Where is the rupture disc located?

During the initial cooling down of a box temperature in a refrigeration system, which of the devices listed is used to prevent excessive gas pressure at the compressor suction for the purpose of prevention of overloading of the compressor driver?

A reheater in an air conditioning system performs what function?

What is one benefit of maintenance of proper air circulation in an air conditioned cargo space?

In a two stage centrifugal air conditioning system, the liquid refrigerant passes through the condenser directly to what component?

In an air conditioning system, what is the name of the chamber where the duct-work originates?

In general, the thermal bulb for a thermal expansion valve used in a reciprocating air conditioning system is usually charged with what substance?

Sea water or low temperature central fresh water is typically provided to a ship's stores refrigeration plant for what purpose?

Zinc plates commonly found in refrigeration systems and used as sacrificial anodes are located where?

Vapor bubbles present in the liquid upon arrival to the thermal expansion valve in a refrigeration system may cause erosion of the expansion valve's needle and seat. This, in turn, could cause what condition?

Moisture entering a typical refrigeration system will most likely produce what effect?

A small obstruction at the thermostatic expansion valve inlet will result in which of the following conditions?

An obstructed expansion valve may be indicated by an incompletely cooled evaporator and what other symptom?

If the superheat value of the thermostatic expansion valve is adjusted too high, what would be the result?

If the superheat setting of a thermostatic expansion valve is set too low, what would be the result, assuming that the system has a single evaporator?

How should small appliances with less than three pounds of refrigerant be charged with refrigerant?

Before charging a refrigeration unit, unless quick disconnect fittings are used, the refrigerant charging hoses should be prepared in what way?

Concerning the charging of refrigerant into a vapor compression refrigerating system, which of the following is true?

Within the territorial limits of the United States, violations of the Clean Air Act of 1990, that includes the intentional release of R-11, R-12, R-22 and other related class I or class II substances may result in fines for each violation per day of what amount?

All shipboard personnel responsible for the maintenance and repair of air conditioning systems using refrigerants covered under the EPA Clean Air Act venting prohibition, must be certified through an approved Environmental Protection Agency (EPA) program to do which of the following?

Persons recovering refrigerant from small appliances must be certified as what type of technician under the EPA Clean Air Act rules?

What would be an example of a small appliance as defined in the EPA Clean Air Act rules?

If you find the pressure of a refrigeration system containing a Class I or Class II refrigerant to be opened for the accomplishment of repairs is 0 psig, what must be done?

Excessively tight drive belts installed between a motor and a refrigeration compressor pulley may cause what condition?

When installing a mechanical shaft seal on a refrigeration compressor, extreme care must be taken to prevent what from happening?

If the discharge reed valves used in a refrigeration compressor are leaking badly, what statement is true?

When one belt of a multiple V-belt drive requires replacing, what will be required?

In addition to the drive belt itself, a V-belt that is tensioned too tight will cause excessive wear to what other drive component?

On a modern refrigerated container unit employing suction modulation for the purposes of capacity control and capacity limitation, what happens when the applied voltage and current draw associated with the normally open (NO) suction modulation valve located in the suction line both increase?

To prevent motor overload during start-up of a hermetically sealed centrifugal refrigeration system, what is true concerning the compressor suction gas variable inlet guide vanes?

A refrigeration compressor used in a multi-box refrigeration system is designed with six of its eight cylinders able to be controlled for variable load conditions. If all of the reefer boxes are currently feeding, what percentage of the total number of compressor cylinders will be loaded after start up?

During operating periods of a multi-box refrigeration system using a capacity controlled compressor, when all of the evaporators of a four box plant are actively being fed with liquid refrigerant, the control oil pressure acting on the hydraulic relay piston will be at what value?

Capacity control of a centrifugal refrigeration compressor can be accomplished by what means?

Why is a purge recovery unit typically fitted on low-pressure centrifugal chillers?

Minor repairs may be performed on low-pressure refrigerant systems without recovering the refrigerant charge if the pressure in the system is raised to atmospheric. How may this be accomplished?

The most cost-effective method of recovering refrigerant from a low-pressure chiller with more than 500 lbs. of refrigerant and to meet EPA requirements is to recover the refrigerant using what protocol?

An arrow stamped on the valve body of a water regulating valve indicates which of the following?

In addition to pressure, most compound and standard pressure gauges used for refrigeration service are also provided with a scale indicating what parameter?

In a large refrigeration system having more than one evaporator, a king solenoid valve should be installed in what location?

Refrigeration system isolation valves are specially designed with a backseat, as well as a front seat. For what purpose are these valves designed in this way?

The receiver used in a refrigeration system performs what essential function?

Hard drawn copper tubing is commonly used in larger refrigeration systems. What statement concerning its use is true?

In a refrigeration plant, what is one vital purpose of the receiver?

In a refrigeration system, from what location would air and non-condensable gases be removed?

Loss of refrigerant during the process of purging of air and non-condensable gases can be kept to a minimum by what action?

In a low-pressure centrifugal chiller, what is meant by the term 'high efficiency purge unit?'

During normal operation, traditionally, how has most of the refrigerant released to the atmosphere from low-pressure systems?

For most multi-box refrigeration systems, the refrigerant sight glass would be located where in the system?

A liquid indicator sight glass is useful in determining whether or not a refrigeration system is sufficiently charged. Where is it generally located in the system?

Why are dehydrators usually located in the liquid line of refrigeration systems?

Which of the devices listed will indicate whether or not a refrigeration system's dehydrator continues to be capable of removing moisture from the circulating refrigerant?

The primary purpose of the liquid line strainer used in a refrigeration system is to prevent dirt and scale from entering what system component(s)?

Moisture is removed from a refrigeration system by what action?

Standard filter/driers used in many commercial type refrigeration units may contain what type of substance?

In a refrigeration system, silica gel is found in what component?

The safety heads of most large reciprocating compressors used in refrigeration systems are held in place by what means?

The carbon seal ring of a refrigeration compressor crankshaft mechanical seal is held in position against the stationary ring face by using what device?

A device used to hold open the refrigeration compressor suction valve during starting to reduce the compression load is called what?

Which of the valves listed is normally closed when charging the refrigeration system through the high side?

When a refrigeration system is being topped off with a small amount of refrigerant through the low side with the compressor running, what should be done?

For the proper control of the air temperature in an air conditioning system using chilled water circulation, which of the listed conditions should remain constant regardless of load changes?

In an air conditioning system, moisture is removed from the air by what means?

A room humidistat initiates the lowering of the humidity of the conditioned supply air to a space, while the actual process is accomplished by what means?

To prevent the unnecessary loading of an air conditioning system while maintaining the designed dry bulb temperature and relative humidity in an air conditioning system, what should be done?

Which of the processes listed would be the most satisfactory method to use to lower the humidity of the air being circulated by an air conditioning system?

Which of the following methods is normally used to control the circulated air temperature of an air conditioning system using chilled water circulation?

When pumping down an air conditioning system to test the low-pressure cutout switch, assuming that the compressor is running, what should be done to initiate the test?

The compressor used in a water-cooled air conditioning system is short cycling. A service check determines that the suction pressure remains above the normal cut-in point during cycling and that the discharge pressure rapidly builds up to the cut-out point while running and gradually falls to the cut-in point during the off cycle. What is likely the cause?

To add small amounts of refrigerant to the low side of an air conditioning system, the refrigerant should be introduced through a particular valve and in a particular state. What valve and state combination is correct?

To add refrigerant to the high side of an air conditioning system, you should close the king valve and introduce the refrigerant through what valve in what state?

A reciprocating refrigeration compressor may be tested for leaking discharge valves by stopping the compressor, turning the discharge service valve all the way in, and then turning the compressor over by hand. If the discharge valves are leaking, the compound gage will show pressures which react in which way?

Leaking suction valves in a refrigeration compressor are indicated by which of the following?

Unusual noise coming from a refrigeration compressor can be caused by which of the following conditions?

Which of the listed statements describes the reason why oil foaming occurs when starting a refrigeration compressor?

Refrigeration systems using forced air circulation evaporators have a tendency to cause rapid dehydration of produce in chill boxes. Which of the following will minimize this dehydration?

In a refrigeration system, what component is installed directly downstream of the thermal expansion valve?

In a dry-type direct expansion refrigeration evaporator, what is true concerning the evaporator coils?

If the evaporator coil horizontal return line of a container refrigeration system is less than 0.875" (2.21 cm) in diameter (considered small); the thermostatic expansion valve sensing bulb should be attached where on the return line?

Which of the installation steps listed is necessary for the proper operation of the thermostatic expansion valve?

Expansion valve maintenance should include which of the following procedures?

When replacing a thermostatic expansion valve power element, what is true concerning the thermal bulb?

What maintenance may be carried out on a thermostatic expansion valve?

A thermostatic expansion valve is properly controlling evaporator superheat. Adjusting this valve to lower the evaporator superheat setting will result in which of the following?

Which statement about calibrating a newly installed thermostatic expansion valve is correct?

Which of the following statements describes the accepted method for testing a thermostatic expansion valve?

What is true concerning the accumulation of air and other non-condensable gases in a refrigeration system?

When a thermostatic expansion valve is installed in a refrigerated container unit, the sensing bulb almost always requires insulation. Why is this so?

Charging liquid HCFC-123 into a system under a deep vacuum could cause what to happen unless necessary precautions are taken?

Which of the following statements is correct concerning the testing of an R-22 refrigeration system for leaks in an enclosed compartment with a halide torch?

When using nitrogen to pressure leak test a system, the nitrogen cylinder should always be equipped with what device or feature?

A refrigeration unit will tend to short cycle when operating under what conditions?

If a refrigeration system, equipped with a reciprocating compressor, has a liquid-line solenoid valve that is leaking during the 'off' cycle, what would this cause?

Moisture in a refrigeration system can cause which of the following conditions?

If a refrigeration compressor had developed a slightly high suction pressure accompanied with an abnormally low suction temperature, the problem could be a result of which of the following?

When a refrigeration compressor motor fails to start, the FIRST thing that should be checked for is what?

In a low-pressure refrigeration system, excessive running of the purge recovery unit generally indicates which probable condition?

If the refrigeration compressor crankcase is sweating or frosting and is operating with an unusual noise, what is most likely the cause?

If a refrigeration system were short of refrigerant, besides an elevated box temperature, what would be an observable symptom?

If a refrigeration compressor were short cycling on the low-pressure cutout switch, what is the most probable cause?

An excessive charge of refrigerant in a thermostatically controlled, air-cooled, refrigeration system using a TXV as an expansion device can cause which of the following?

If a refrigeration compressor using a thermostat as a primary controller is running continuously without significantly lowering the temperature in the refrigerated space, which of the following is most likely the trouble?

Excessive moisture being collected in the purge unit of a low-pressure refrigeration system could indicate which probable condition?

An evaporator coil of a single evaporator, air-cooled refrigerator is accumulating excessive frost due to a failure of the defrost mechanism. If the refrigerator features a thermostatically controlled box solenoid and a low-pressure cutout controlled compressor, as well as a high-pressure cutout, in terms of the compressor, what would be the most likely operating symptom?

During tests to discover why a refrigeration compressor is running continuously, it is determined that the refrigerated space temperature is slightly above normal without ever reaching the desired minimum temperature. Suction and discharge pressures are normal for the corresponding box temperature. In this situation, what should you suspect?

In a refrigeration system, the push-pull technique can be used for the recovery of the refrigerant in what state?

What is the correct color-coding of refrigerant recovery cylinders regardless of the refrigerant contained within?

The gas that exists in the stratosphere forming a protective shield that helps to protect the environment from the harmful effects ultraviolet radiation is called what?

Which of the following substances is normally classified as a low-pressure refrigerant?

What is the color-coding for a storage container of R-134a refrigerant?

The "tare weight" of a refrigerant storage cylinder refers to what weight?

Alkyl benzene ISO 32 cSt synthetic refrigerant oil is miscible and suitable to use with which of the following refrigerants?

The amount of HCFC-123 in a storage cylinder is measured by what means?

Traditionally, which of the listed refrigerants has been more suitable than the others for use in a centrifugal refrigeration compressor?

Which of the fluids listed is suitable for use as a secondary refrigerant?

According to 46 CFR, Part 58, for protection purposes, what is required of all refrigeration systems?

Coast Guard Regulations (46 CFR Part 113) require refrigerated spaces that can be locked from the outside and that cannot be opened from the inside to have an audible alarm. Where is the audible alarm required to be?

With regards to shipboard refrigeration systems, after July 1, 1992, what action became illegal?

Coast Guard Regulations (46 CFR Part 58) require a method for the relieving pressure of an over pressurized refrigeration system. Which of the following statements complies with these Regulations?

When opening or closing compressor service and line isolation valves on a typical refrigeration system that is fitted with packed valves, what must you do?

What is the purpose of running a refrigeration compressor in short intermittent spurts or throttling the suction isolation valve when starting the system after a prolonged shutdown?

When starting a reciprocating refrigeration compressor that has been shut down for a period of time, you should manually throttle which valve?

Concerning the operation of refrigeration systems, frosting or sweating of a liquid line is usually indicative of what condition?

The surging that occurs in a centrifugal air conditioning compressor is a result of what conditions?

In an air conditioning system, low discharge head pressure associated with a reciprocating compressor can be the result of what condition?

Sludge may form in the crankcase of an air conditioning compressor as a result of what condition?

The pressure in the part of a high-pressure refrigeration system about to be opened for a non-major repair should be brought to what value?

What is the maximum volume to which refillable refrigeration cylinders should be filled?

A box solenoid valve used in a refrigeration system should be installed in what manner?

The FIRST thing to do to ensure that a refrigeration unit will not start while undergoing repairs is to do what?

Which of the precautions listed should be taken before opening any part of a refrigeration system for the purpose of accomplishing non-major repairs?

When a refrigeration compressor has developed a high head pressure as a result of a refrigerant overcharge, what should be done to compensate for or to correct this situation?

In a refrigeration system, the bulb for the thermal expansion valve is always located where?

In a refrigeration system, the pressure within the power element of a thermostatic expansion valve depends directly upon what factor?

What is one function of the thermal expansion valve used in a refrigeration system?

In a vapor compression type refrigeration cycle, the refrigerant temperature decreases the most when passing through which system component?

When the sensing bulb of a thermostatic expansion valve is charged with a fluid different from the charge used in the system, what name of the charge is associated with the power element?

The thermostatic expansion valve in a refrigeration system further opens when the diaphragm flexes downward. With all other conditions being the same, what single condition causes this?

A typical shipboard domestic multi-box refrigeration system operates with one compressor and condenser. What is the purpose of the sensing line connected to the thermal bulb at the evaporator coil outlet?

Besides the evaporator pressure, the thermal expansion valve reacts directly to changes in what parameter?

Constant superheat is maintained at the evaporator coil outlet of a refrigeration system or unit by the action of what device?

Concerning the proper installation of the sensing bulb of a thermal expansion valve that is attached to the evaporator tail coil on a horizontal run, what statement is true?

In refrigeration systems with multiple evaporators, the metering of refrigerant to each refrigerated space evaporator is accomplished by what device?

Which of the conditions listed could cause excessively low refrigerant pressure at the compressor suction of a TXV controlled refrigeration system?

High suction pressure accompanied by low suction temperature to a refrigeration system compressor is caused by which of the following?

Low compressor head pressure in a refrigeration system can be caused by which of the following?

If the running suction pressure at the refrigeration compressor of a TXV controlled air- cooled refrigeration system is below normal, which of the following can be a cause?

In an operating, water-cooled, multi-box refrigeration system, both low discharge and high suction pressures are being simultaneously experienced. The probable cause for this condition is which of the following?

If increasing the cooling water flow to a refrigeration condenser fails to lower the condenser pressure, the probable cause may be due to what condition?

What is true concerning frost build-up on the evaporator coils of a multi-box direct expansion refrigeration system?

Some 'hot gas' defrost systems reheat the refrigerant just prior to its returning to the compressor for what purpose?

What is the physical state and pressure condition of refrigerant as it enters the condenser of a typical refrigeration system?

The term 'oil foaming' in refrigeration practice, is used to describe what event?

What is the pressure and condition of the refrigerant entering the receiver of a refrigeration system?

What is the physical state and pressure condition of refrigerant as it leaves a receiver in a typical refrigeration system?

If passive recovery is used on a small appliance fitted with a capillary tube as a metering device with a non-operating compressor, the recovery should be made through what means?

Technicians servicing small refrigeration appliances can employ what type of recovery equipment?

Which recovery procedure should be used to minimize the loss of oil from the system during the recovery of refrigerant from small appliances such as a water cooler?

What is true concerning highly contaminated refrigerant recovered from burned out small appliances?

For safe storage, the maximum allowable temperature to which refrigerant bottles should be exposed is what temperature?

Overfilling a refrigerant container is extremely dangerous because of the high pressures generated. The generation of pressure is the result of what?

Personnel servicing refrigeration systems and subject to the exposure to commonly used refrigerants should wear what type of personal protective equipment?

Why can CFC or HCFC refrigerants leaking into a confined space or in limited surroundings cause suffocation?

In the presence of an open flame or hot surfaces, chlorinated fluorocarbon refrigerants decompose and form what chemical substance?

The low-pressure cutout switch settings vary with the refrigerant used and the temperature application. If the low-pressure cutout switch for a particular application is set with a cut- in pressure of 5 psig, what would be the cut-out pressure if the differential is 7.5 psig?

In a multi-evaporator refrigeration system, a solenoid valve is installed in the liquid line prior to what device?

The sensing line for the low-pressure cutout switch for a refrigeration system is typically connected at what location?

What is the purpose of the low-pressure cut-out switch as used as a primary controller for a refrigeration system or unit?

The thermostat controlling the operation of the solenoid valve to a refrigerated box evaporator senses what temperature?

A box solenoid valve used in a multi-box refrigeration system is operated by electromagnetic action by what control device?

Which of the listed operations will cause an automatically controlled refrigeration compressor to restart if the system features a pump down cycle?

In a refrigeration system featuring low-side pump down prior to the automatic shut down of the compressor, the temperature of the refrigerated space is controlled by the action of a thermostat wired to what device?

How does a refrigeration solenoid valve differ from a modulating valve?

A liquid line solenoid valve controls refrigerant flow to the evaporator by what means?

If a condenser coil of an air-cooled container refrigeration system becomes dirty and requires cleaning, what would be an acceptable method of cleaning?

When checking zinc plates or pencil zincs in the refrigerating system condenser, what should you do?