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Z51 REFRIGERATION TEST LATEST TEST | ALL
QUESTIONS AND CORRECT ANSWERS |
LATEST VERSION | GRADED A+ | VERIFIED
ANSWERS
A refrigeration system uses jet ejector to raise settled oil mixed with refrigerant to the oil pump. If a restriction in the refrigerant flow to the jet ejector develops: ------CORRECT ANSWER---------------There may be insufficient head to lift the oil An indirect, low temperature refrigerant system frequently uses glycol, instead of salt brine as the intermediate cooling medium. An advantage of this choice is: ------CORRECT ANSWER---------------The elimination of corrosion In relation to the suction pressure of a compressor, the reading on the oil pressure guage should read in the range, closer to: ------CORRECT ANSWER---------------15 to 30 PSI higher Non-condensable gases like air, oil vapor, or nitrogen travel through a refrigerant system with the refrigerant they usually accumulate in the: ------ CORRECT ANSWER---------------Condenser The advantage of forced draft cooling tower over natural draft cooling towers is: ------CORRECT ANSWER---------------Smaller tower size
The sole refrigeration engineer on duty in a building is permitted to leave the building refrigeration system when it is in operation only when: ------ CORRECT ANSWER---------------Relieved by another licensed refrigeration engineer A system controlled by a TXV shows high discharge pressure and high normal subcooling. The cause is most probably a: ------CORRECT ANSWER---------------Refrigerant overcharge Which of the following is a correct statement? ------CORRECT ANSWER---- -----------2.5 gallons of water weighs 20.8 pounds Liquid level gauge glasses (except the bull's eye) are generally equipped with: ------CORRECT ANSWER---------------Automatic shut off valves only Copper and aluminum are frequently used for condenser tubes in refrigeration system. These metals are used because of their: ------ CORRECT ANSWER---------------High heat transfer coefficient Assume that a refrigeration engineer has a choice of four valves to select from. Which of the following is the most effective type of valve to control pressure? ------CORRECT ANSWER---------------Plug valve Where must the Material Safety Data Sheets be located? ------CORRECT ANSWER---------------Where available to all employees
Of the following, the most common metering device used today in reciprocating commerical refrigeration system under three tons capacity is: ------CORRECT ANSWER---------------TEV The purpose of wear rings in a centrifugal pump is to: ------CORRECT ANSWER---------------Prevent wearing of the pump housing and impeller You are the engineer running a 2000-ton (steam driven turbine) centrifugal refrigeration system, a refrigeration system supplies chilled water to a college campus with multiple buildings. While making rounds, you notice that the condenser water coming back down from the 9-cell cooling tower on the roof is at a temperature of 90F. You want to make an adjustment to bring the temperature of the condenser water down to 85F. Which one of the following immediate actions would you take? ------CORRECT ANSWER---------------Increase the speed of the cooling tower fans A water chiller is equipped with a reciprocating compressor, a thermostatic expansion valve, and an air cooled condenser. A restriction in the refrigerant liquid line would result in: ------CORRECT ANSWER--------------- High suction superheat A solenoid valve is used to allow a reciprocating refrigeration machine to adapt to the load on the system. The opening of the solenoid valve is caused by: ------CORRECT ANSWER---------------An electrical current creating a magnetic field The process by which refrigerant is extracted and cleaned for reuse without requirements for reclamation is called: ------CORRECT ANSWER------------- --Recycling
A centrifugal compressor is in operation with suction pressure is 3 PSIG and the discharge is 10 PSIG. What is the atmospheric pressure is 14. which is the ratio closets to: ------CORRECT ANSWER---------------1. You are the engineer running a 2000-ton (steam driven turbine) centrifugal refrigeration system, a refrigeration system supplies chilled water to a college campus with multiple buildings. The panel display on the refrigeration system indicates that the problem is water flow. What do you do? ------CORRECT ANSWER---------------Check the condenser water pump and restart the refrigeration system Electrical current is measured in: ------CORRECT ANSWER--------------- Amperage How would you put an additional pump online? ------CORRECT ANSWER-- -------------Open suction valve, open discharge valve gradually Of the following, the major advantage of a shell and coil condenser is ------ CORRECT ANSWER---------------There is less danger of developing leaks An engineer needs to vary the flow of refrigerant in a refrigeration system. Which operation in the flow of the system does not include: ------CORRECT ANSWER---------------Solenoid valve Thermal bulb is attached to the suction pipe between the evaporator coil and the compressor by an insulated line. Assume that the machinery room
To convert water at 32 degrees F to ice at the same temperature a refrigeration system must remove: ------CORRECT ANSWER--------------- The latent heat of fusion Efficiency of the refrigerant cycle is affected by the operations of the condenser. Of the following, a more efficient centrifugal compressor operation results from: ------CORRECT ANSWER---------------Lowering the condensing pressure The heat removed from the refrigerant in a condenser is: ------CORRECT ANSWER---------------Sensible and latent heat The refrigerant unit that you have been assigned to is being taken out of service for a major repair. You have been assigned to withdraw refrigerant for storage in suitable containers. According to the NYC Fire Code, you must ensure that the containers: ------CORRECT ANSWER---------------Are approved by the US Dept. of Transportation Which of the following best describes how the cylinder unloader works? ---- --CORRECT ANSWER---------------Keep in the suction valve opened while the compressor is in the return stroke In most semi-hermetic compressors, the suction vapor is used to: ------ CORRECT ANSWER---------------Cool the motor
The amount of refrigerant that flows through the orifices of an economizer is determined by the: ------CORRECT ANSWER---------------Differences between the high side and low side pressure The installation of an inline refrigerant cleaning system is advisable: ------ CORRECT ANSWER---------------To remove impurities from the system The type of refrigerant system that is least likely to leak refrigerant into the building space that are being cooled: ------CORRECT ANSWER--------------- Indirect system The suction pressure of a reciprocating compressor is 65 PSIG. The discharge pressure of this compressor is 120 PSIG. The atmospheric is 14.7 PSI. The compression ratio for the given condition is closest to: ------ CORRECT ANSWER---------------1. A superheated vapor is: ------CORRECT ANSWER---------------Dry vapor above the saturation temperature A refrigerant engineer verifies that a condenser water pump is cavitating. Of the following, the most likely cause for this condition is: ------CORRECT ANSWER---------------A faulty cooling tower water level controller A centrifugal water pump is known as a lift pump when the: ------CORRECT ANSWER---------------The water supply to the pump suction inlet is below the pump level
A low side float valve is used to maintain: ------CORRECT ANSWER--------- ------The level of the refrigerant in the evaporator Regarding fire safety, which ASHRAE refrigerant safety classification indicates no flammability and lower toxicity? ------CORRECT ANSWER------ ---------A When an expansion valve is operating properly, at the end of the evaporator will contain: ------CORRECT ANSWER---------------Only superheated vapor What information is not contained in a Material Safety Data Sheet? ------ CORRECT ANSWER---------------Cost of the material In a steam turbine, what is the function of the Kingsbury thrust bearing? ---- --CORRECT ANSWER---------------Maintain axial positioning of the rotor shaft A centrifugal water pump is considered to the fully primed when? ------ CORRECT ANSWER---------------The pump is full of liquid Copper tubing refrigerant lines must be installed for a new system. It is a well known service practice that tubing collapses at bends that must be made, the refrigerant engineer should use? ------CORRECT ANSWER------- --------Level type tubing bender
A reciprocating compressor is making a knocking sound during operation. If the refrigerant worn parts are not causing the knocking, what probably the cause? ------CORRECT ANSWER---------------Slugging of the liquid refrigerant In order for a refrigerant to become superheated, it must be heated in a section of the low side refrigerant line: ------CORRECT ANSWER--------------
- Where no liquid refrigerant is present All liquid has been recovered from a system to be overhauled, the system: - -----CORRECT ANSWER---------------Should not be opened until all vapor has been recovered When a refrigerant engineer uses a portable compressor recovery unit to remove vapor refrigerant from a refrigeration system the removal rate of the refrigerant will gradually slow down because? ------CORRECT ANSWER---- -----------The compressor efficiency is decreasing You are the engineer running a 2000-ton (steam driven turbine) centrifugal refrigeration system, a refrigeration system supplies chilled water to a college campus with multiple buildings. During the course of making your rounds, you check the 9 cell cooling tower on the roof. You note the water level in all of the cooling tower cells is very low. Which one of the following immediate actions would take? ------CORRECT ANSWER---------------Add additional make up water to the cooling tower A rooftop water cooling tower is connected to a water pump in the building basement with a 12 inch diameter pipe. With the pipe turned off, a pressure gauge at the pumps inlet show a pressure of 140 PSIG the height of the
What is the function of the turbine auxiliary oil pump? ------CORRECT ANSWER---------------Establish oil pressure during turbine start up The rupture disc for a low pressure centrifugal refrigeration machine is normally located on the: ------CORRECT ANSWER---------------Compressor suction What is the primary reason ribbed metal piping is used for electrical wires connected to the refrigeration system shown below? ------CORRECT ANSWER---------------It allows for flexibility and accounts for vibrations A multi cylinder reciprocating compressor uses cylinder unloaders to regulate capacity, what would not occur if some of the unloaders fail to operate when needed? ------CORRECT ANSWER---------------The chill water temperature will increase As shown in the picture below, the suction gauge of a condenser water pump reads 55 PSI. The pipe supplying the pump is 75 feet long and 12 inches in diameter. Approximately, how many gallons of water do you expect to obtain if the pipe is drained completely? ------CORRECT ANSWER--------------- 440 A water chiller system uses refrigerant R-123. A leak in the evaporator shell may result in: ------CORRECT ANSWER---------------A higher than normal high side pressure
Capacitors are used on refrigeration motors. Of the following, the function of these devices is to: ------CORRECT ANSWER---------------Store electrical chargers during starting and running the motor Of the following, centrifugal refrigerant machine is best characterized by: --- ---CORRECT ANSWER---------------A high volume, low pressure machine Which of the following ASHRAE refrigerant safety classifications is the most flammable? ------CORRECT ANSWER---------------A Which of the following correctly describes the object in the picture below? -- ----CORRECT ANSWER---------------Standpipe hose outlet, to put out fires in case of emergency Modern compressors usually seal the rotating shaft as it exits the compressor housing a spring ------CORRECT ANSWER---------------Metal or carbon The British Thermal Unit (BTU) is the measurement of heat of energy. If 10 BTU's are transferred to 10 pounds of water, the water temperature increase will be closest to: ------CORRECT ANSWER---------------1 deg F A reciprocating compressor cylinder has a 10 inches bore and 14 inches stroke. The volume of the refrigerant , in cubic inches, will be closer to: -----
- CORRECT ANSWER--------------- 1099
The primary way of achieving capacity control of a centrifugal compressor is by: ------CORRECT ANSWER---------------Adjustment of the impeller inlet pre-rotation vanes Cooling tower water requires the addition of chemical additives in order to: - -----CORRECT ANSWER---------------Reduce the formation of scale and algae In the picture below describes the equipment's function: ------CORRECT ANSWER---------------Remove non-condensables from the condenser The viscosity of lubrication oil is described by a number. A low viscosity number describes oil that: ------CORRECT ANSWER---------------Flows easily The most likely reason for refrigeration engineer to use a psychrometer is to measure: ------CORRECT ANSWER---------------Relative humidity level of the atmosphere The most important reason to use at least two compressors in a cascade system is to: ------CORRECT ANSWER---------------Avoid very high compression ratio for each compressor The suction service valve of a reciprocating compressor is front seated and the compressor runs until the low pressure cut out shuts the compressor off. When the machine is stopped, the refrigeration engineer notices that the suction pressure increases rapidly. The most probable cause of this
pressure rise is: ------CORRECT ANSWER---------------Malfunction of a compressor valve Regarding the functioning of a steam turbine, why is it advisable to keep moisture in the inlet low as possible? ------CORRECT ANSWER--------------- Keeps turbine blades wear to minimum According to the attached Material Safety Data Sheet, R-134 is a: ------ CORRECT ANSWER---------------Clear, odorless liquid and vapor Under normal conditions, the refrigerant enters the compressor as a: ------ CORRECT ANSWER---------------Low pressure, super-heated vapor and leaves as a high pressure vapor While operating an R-22 single acting compressor system, the refrigeration engineer noticed oil foaming in the crankcase. This condition most likely, would have been caused by a: ------CORRECT ANSWER--------------- Sudden drop in the crankcase pressure Assume that an engineer is able to observe refrigerant water and oil together. The fluids would settle in the container from top to bottom as follows: ------CORRECT ANSWER---------------Oil, water, refrigerant What is the function of the vacuum breaker in the steam turbine? ------ CORRECT ANSWER---------------To achieve a faster cost down cycle
The following is a desirable property in a refrigeration ------CORRECT ANSWER---------------High latent heat The cooling medium for an evaporative condenser is: ------CORRECT ANSWER---------------Air and water The ratio of the actual pressure of water vapor in the atmosphere, to the saturated pressure of given temperature is? ------CORRECT ANSWER------ ---------Relative humidity The only refrigerant/temperature chart available to a refrigerant engineer lists the temperature is degrees Celsius. If the chart indicates a Celsius temperature of 4 degrees to equivalent to F ------CORRECT ANSWER------- --------39.2 degrees A refrigerant engineer was instructed to charge a 60 ton plant with R-134A refrigerant. The refrigerant engineer will most likely find the charging valve on the: ------CORRECT ANSWER---------------Low pressure side of the system A refrigerant engingeer verifies that a chilled water pump is cavitating. Of the following, the most likely cause for this condition is? ------CORRECT ANSWER---------------Water leaks through the mechanical seals
There is an decrease in the efficiency of a reciprocating compressor. This mostly likely caused by? ------CORRECT ANSWER---------------Leaking suction valve The suction and discharge valve of the reciprocating compressor are mounted as follows: ------CORRECT ANSWER---------------Discharge valve on top of the valve plate and suction valve below You are the engineer running a 2000 ton (steam driven turbine) centrifugal refrigeration system, a refrigeration system supplies chilled water to a college campus with multiple buildings. While making your rounds, you noticed that the discharge pressure of your condenser water pump is significantly lower than the normal. Which following action would you avoid taking: ------CORRECT ANSWER---------------Put on an additional surface condenser pump and lower the chilled water set point A water pump is discharge against head 92 feet of water, this is approximately to a pressure of: ------CORRECT ANSWER--------------- 40 Which of the following will connect to the middle port on a gauge manifold? ------CORRECT ANSWER---------------Vacuum pump The most important reason for installing a muffler in reciprocating refrigerant machine is? ------CORRECT ANSWER---------------To contain the compressor pulsation noise
