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Rupture members, when used in parallel with a relief valve, are not to exceed _____% above designed working pressure 20% Butterfly valve: where can it be used? Can be used on the inlet and outlet of a water pump What electrical motor protection device automatically resets itself? The thermal protector 746 watts equals how many kilowatt hours? .746 kilowatt hours What position is the liquid line service valve normally in? Back-seated In an operating evaporator, oil stays on top of which refrigerant? Carbon dioxide, R- 744 At what pressure does the relief valve blow on a high pressure machine? 300 psi What would indicate a restriction (such as dirt or scale) in the liquid line? Frost immediately after the restriction What does solubility mean? The ability of a refrigerant to mix with other substances Charging Vapor — In a compression system, where do you charge the vapor? Suction side of the compressor at the Suction Service Valve When comparing a brine with s PH of 8 to one with a PH of 10, its alkalinity is: 100 times greater (ex. PH 8 to PH 9 is 10 times greater) In an efficiently operating induced draft cooling tower, the leaving water is between: Dry bulb and wet bulb temperature To produce the desired evaporator temperature, the power input is reduced by keeping head pressure... Head pressure as low as possible & suction pressure as high as needed The accumulator is usually between the... Compressor and evaporator
An oiling system in a large centrifugal system should consist of at least... Reservoir, pump and distribution lines In an evaporator that chills brine, the greatest cooling effect on the brine results from the... Boiling of low pressure liquid The flow of weak liquor to the absorber is controlled by A) gas pressure B) throttling device C) float valve D) pressure of the strong liquor pump B) throttling device The best way of detecting ammonia brine is by using A) CO2 gas B) potassium of lime C) Nessler reagent D) carbonate of soda C) Nessler reagent The best time to purge an ammonia plant with 250 lbs. of ammonia is A) during shut-down, because you will lose ammonia B) while charging the plant C) during operation D) none of the above C) during operation What will make the strong liquor in the absorber decrease? A) expansion valve open too much B) A decrease in evaporator load C) An increase in evaporator load D) Too much steam on the generator B) A decrease in evaporator load Which of the following statements is incorrect? A) A service valve is a key-operated shut-off valve used during shipment, installation and repairs B) Brine is a liquid cooled by refrigeration and used for the transmission of heat C) A fusible plug has a set-temperature fusible member to relieve pressure D) A rupture member automatically ruptures at a predetermined temperature D) A rupture member automatically ruptures at a predetermined temperature Oil in a refrigerant should A) have a high pour point B) have a low flash point
C) discharge line between compressor and condenser D) liquid line between receiver and expansion valve D) liquid line between receiver and expansion valve R- 22 — What does it smell like? Odorless Desirable characteristics of a refrigerant: A) High __________ B) Low __________ A) High critical point B) Low freezing point Centrifugal Feed Water Pump A) Start-up procedure B) Shut-down procedure A) Start-up procedure
- Lock-out, tag-out
- Close discharge valve
- Open suction valve
- Turn on
- Open discharge valve B) Shut-down procedure
- Lock-out, tag-out
- close suction valve
- close discharge valve In order to vary the capacity of an absorption plant, you should regulate the.. Flow of the water to the condenser 600,000 btu per hour equals how many tons of refrigeration? A) 300 B) 3, C) 500 D) 50 D) 50 Heat transfer takes place by A) evaporation, conduction and condensation B) radiation, conduction and convection C) condensation, evaporation and radiation D) sublimation, evaporation and convection B) radiation, conduction and convection
Refrigerant recovery is defined as A) Removing the refrigerant from a system and storing it in an external container, with the lowest emissions possible. B) Reprocessing a refrigerant into a new product that can be reused in another system. C) The process of cleaning a refrigerant of dirt and contaminates, such as oil, acid, foreign material and non condensibles. D) None of the above. A) Removing the refrigerant from a system and storing it in an external container, with the lowest emissions possible. A 10-ton refrigeration unit has a capacity of A) 2,000 btu/minute B) 12,000 btu/minute C) 20,000 btu/minute D) 144,000 btu/day A) 2,000 btu/minute In an absorption system, the medium normally used to vaporize refrigerant and increase its temperature is A) water B) propane C) ethylene D) steam D) steam Any water present in the refrigerant side of a Freon refrigerating system causes a A) clogged oil trap B) frozen discharge valve C) clogged scale trap D) frozen expansion valve D) frozen expansion valve The subcooling effect of the liquid refrigerant just before the expansion valve causes increased A) horsepower B) refrigeration effect C) expansion valve capacity D) refrigerant flow B) refrigeration effect In a flooded evaporator using an accumulator and float valve, flash gas A) passes directly into the evaporator B) passes directly into the suction line
During start-up, this added capacitance in series with the start winding causes a greater phase angle between the run and start winding, which gives the motor more starting torque. When the start switch opens, the start capacitor is taken out of the circuit. However, the run capacitor and start winding stay in the circuit. The run capacitor stays in series with the start winding for extra running torque. The capacitor, being in series with the start winding during the running mode, also limits the current through the start winding so the winding will not get hot. This motor is actually a permanent split capacitor (PSC) motor when running. The start capacitor is used for nothing but added staring torque. The capacitance of two capacitors in parallel add their values the same as resistors do in series. If the run capacitor has a capacitance of 10 microfarads and the start capacitor has a capacitance of 110 microfarads, their total capacitance would be added to be 120 microfarads.`` On which tachometer do you mark the rotating object with reflecting tape? A) The electronic tachometer (stroboscope) B) The digital photo tachometer C) The centrifugal-type tachometer D) The chronometric tachometer B) The digital photo tachometer One characteristic of a synchronous motor is that it operates at A) high starting torque B) constant speed C) causes lagging power factor D) all of the above B) constant speed If during does not occur in a refrigerating system, what is the result? A) High-head pressure B) Low-condenser pressure C) Low-head pressure D) None of the above A) High-head pressure A wound-rotor induction motor with external resistance is a A) multispeed motor B) constant-speed motor C) single-speed motor D) waterproof cover A) multispeed motor In a Freon refrigerating system in which all piping is made up of hard copper fittings and streamlined "wrought"-type fittings, the joints should be A) screwed
B) soldered or brazed C) flanged with ground faces D) flanged with lined rubber gaskets B) soldered or brazed If any piece of equipment can be isolated as a separate unit A) A gauge must be present B) a safety valve must be installed C) valves must be locked D) the system must be able to run without it B) a safety valve must be installed On a 220 volt, three phase, 4-wire electric service, any line will read A) 220 volts B) 440 volts C) 70 volts D) 110 volts D) 110 volts If the specific heat of glass is .196, how many btu are needed to raise the temperature of 10 pounds of glass from 50° F to 70°F? A) 40. B) 39. C) 59. D) 36. B) 39. A direct expansion (bare) coil evaporator is used to maintain a meat storage space at 28 to 30° F. The last coil has no frost. It can be said that this system is A) condition is acceptable to maintain a high plant efficiency B) is a direct indication of air in the system C) indicates moisture in the refrigerant D) is a direct indication that the coil is being starved D) is a direct indication that the coil is being starved Fuses and circuit breakers are safety devices for electric motors but they will not protect motors against A) short circuit B) heavy overload C) burnout D) overheating D) overheating
In order to vary the specific capacity of an absorption refrigerating plant, an operating engineer should regulate the A) Flow of steam to the generator, and adjust the expansion valve. B) Relief valves on the generator, and the speed of the NH2 pump. C) Speed of the absorber pump. D) Flow of water to the condenser. A) Flow of steam to the generator, and adjust the expansion valve. The refrigerant least miscible in oil is A) CO B) R- 12 C) R- 40 D) R- 141 A) CO The first sign that the drum of ammonia refrigerant is almost empty is A) The appearance of frost on the lower end of the drum B) The appearance of fog in the vicinity of the drum C) A hissing or whistling noise in the drum D) A gurgling noise C) A hissing or whistling noise in the drum What is the total force exerted on a piston 3" in diameter if pressure in the cylinder is 100 psig? πR2 x pressure 1.14 x 1.52 x 100 3.14 x 2.25 x 100 7.065 x 100 706.5 psi Breathing apparatus
- A machine room with 1-1,000 lbs. of refrigerant needs how many masks?
- A machine room with 1,001-2,000 lbs. of refrigerant needs how many masks?
- 1 - 1,000 lbs. = 1 mask
- 1,001 - 2,000 lbs. = 2 masks Safety valve huddling chamber
- How is the design important to the function of the huddling chamber?
- What is a huddling chamber?
- Where is the exact location of it on the machine?
- Design- The huddling chamber has a greater diameter that the pipe thereby having a greater total force to open the relief valve
- Pressure relief valve
- On the suction elbow Depletion of the ozone results in three types of skin cancer. Which of the following are the most common non-malignant type of skin cancer? A) Basal, squamous B) Malignant melanoma C) Cataracts D) Leishmaniosis A) Basal, squamous The suction temperature of an ammonia system reads 50° F. This temperature is equivalent to _____ psi. 75 psi During the re-expansion of the compressor cycle A) The suction valve is open B) The suction valve is closed C) The discharge valve is open D) None of the above B) The suction valve is closed Where is the king valve located? Mention some details about it. The king valve is located next to the condenser or receiver outlet; it can be located on the receiver; it can be used as the liquid line service valve. How is an evaporator defrosted? Hot gas from the discharge line is sent to the evaporator after the metering device. Freon-12 has similar high and low pressures to what other refrigerant? R-40, Methyl Chloride Evaporator -
- If the pressure drop was less than 2.5 lbs., what would the system have?
- 2.5 lbs. but less then than 5 lbs.
- 5 lbs. or more?
- Nothing
- External equalizer
- Multicircuit system Oil safety switch
- Operating pressure _____?
- 2 pressures .
- Time delay -
- Cuts off at _____.
Recovering refrigerant (except R-22)
- Less than 200 lbs. of refrigerant?
- More than 200 lbs. of refrigerant?
- +200 lbs. at 15" Hg. Purger — NH
- what is in a purger?
- What is the purpose of the purger?
- What reclaims refrigerant after it is reclaimed in an automatic purger?
- Where is the purge unit?
- What is the cycle?
- The purger has a refrigerated coil in it
- To remove non-condensable gas
- Aqua ammonia
- On the condenser
- From condenser to purge compressor, purge, evaporator (expansion valve to condenser?) What is the formula for volume? Volume = πR2 x L On what pressure doe the relief valve blow on a high-pressure machine? 300 PSI In an operating evaporator, oil stays on the top of which refrigerant? Carbon dioxide, R- 744 Rupture members, when used in parallel with a relief valve, are not to exceed ___% above designed working pressure. 20% Butterfly valve — where can it be used? Can be used on the inlet and outlet of a water pump What position is the liquid-line service valve normally? Back-seated 746 watts equals how many kilowatt hours? .746 kilowatt hours What electrical motor protection device automatically resets itself? The thermal protector What does the electronic capacity control module do? Modulates the inlet valve actuator What does the purge system do? Removes non-condensable gases and water
A wound-rotor induction motor with external resistance is a A) Multispeed motor B) Constant-speed motor C) Single-speed motor D) Waterproof cover A) Multispeed motor On characteristic of a synchronous motor is that it operates at A) High starting torque B) Constant speed C) Causes lagging power factor D) All of the above B) Constant speed If any piece of equipment can be isolated as a separate unit, A) A safety gauge must be present B) A safety valve must be installed C) Valves must be locked D) The system must be able to run without it B) A safety valve must be installed If purging does not occur in a refrigerating system, what is the result? A) High-head pressure B) Low condense pressure C) Low head pressure D) All of the above A) High-head pressure In a Freon refrigerating system in which all piping is made up of hard copper fittings and streamlined "wrought"-type fittings, the joints should be A) Screwed B) Soldered or brazed C) Flanged with ground faces D) Flanged with lined rubber gaskets B) Soldered or brazed One effect of noncondensable gas in a system is A) High suction pressure B) Low suction pressure C) High condenser pressure D) Low condenser pressure C) High condenser pressure
C) 2,900 cfm D) 3,050 cfm C) 2,900 cfm In an automatically operated, flooded shell-and-tube cooler, an electric float switch is used primarily to A) Control the flow of brine into the tubes B) Control the flow of refrigerant into the shell C) Purge oil from the cooler D) Purge noncondensable gas from the cooler B) Control the flow of refrigerant into the shell A 10-ton refrigeration unit has a capacity of A) 2,000 btu per minute B) 12,000 btu per hour C) 20,000 btu per minute D) 144,000 btu per day A) 2,000 btu per minute A pressure or temperature response mechanism for automatically stopping the operation of the pressure-imposing element is the A) Pressure-limiting device B) Pressure-relief valve C) Pressure-imposing device D) Pressure-relief device A) Pressure-limiting device Any water present in the refrigeration side of a Freon refrigeration system causes a A) Clogged oil trap B) Frozen discharge valve C) Clogged scale trap D) Frozen expansion valve D) Frozen expansion valve The minimum required rated discharge capacity of the pressure relief valve device or fusible plug for a refrigerant-containing vessel is determined by the following formula: C=Fd1. What is the "C" equal to? A) Btu/minute B) Refrigerant pressure C) Air in pounds/minute D) Cubic feet/minute A) Cubic feet per minute
In a flooded evaporator using an accumulator and float valve, flash gas A) Passes directly into the evaporator B) Passes directly into the suction line C) Does no occur D) Stays in the receiver E) A minimum of every 2 years B) Passes directly into the suction line According to the provisions of the rule, a soldered joint is a gas-tight joint obtained by the joining of metals with metallic mixtures or alloys that melt at temperatures below A) 700° F and above 100° F B) 800° F and above 200° F C) 900° F and above 350° F D) 1,000° F and above 400° F D) 1,000° F and above 400° F The capacity of an evaporative condenser will A) increase as the entering air wet-bulb temperature decreases B) increase as the entering air wet-bulb temperature increases C) not change with changes in the entering air wet-bulb temperature D) decrease as the entering air wet-bulb temperature decreases A) increase as the entering air wet-bulb temperature decreases What is capacity? The ability of a machine to move btu's Refrigerant properties can be classified as __________ and __________. Thermodynamic; physical True or False — R-22 is always a miscible refrigerant False Of the following thermal properties of a refrigerant, the undesirable ones are A) High viscosity, low pour point B) High latent heat of evaporation C) Low critical and high freezing temperature D) High viscosity and high film heat conductivity C) Low critical and high freezing temperature When heated, R-12 changes to A) Hydrochloric acid B) Phosgene C) Carbon acid D) Chlorine gas
__________ btu/minute __________ btu/second
- 288,000 btu/day
- 12,000 btu/hour
- 200 btu/minute
- 2.2 btu/second Who is responsible in a plant to assure refrigerant cylinders are within the hydrostatic test dates? A) Operating engineer B) Plant manager C) Chief engineer D) Owner D) Owner If all of the hydrogen atoms have been replaced in the base molecule by chlorine and fluorine, the refrigerant is said to be A) fully halogenated B) partially halogenated C) hydrochlorofluorocarbon D) azeotropic A) fully halogenated Butterfly valve - Where can it be used? Can be used on the inlet and outlet of a water pump Which statement is true concerning Ternary Blends? A) Leak at faster rates than other refrigerants B) Leak at uneven amounts due to vapor pressures C) Leak at even rates D) Leak on the high side due to high pressure B) Leak at uneven amounts due to vapor pressures How many pounds of refrigerant can be stored in a machine room if the machine has 1,000 lbs. in it? 200 One vertical foot in a riser equals how many psi? .433 psi Sulphur Dioxide — discharged SO2 may be put in a tank of __________ and not be used for any other purpose Absorptive brine What is the formula for gallons of water in a pipe? 2.04 x Diameter2 x length/
How much ice does a machine rated at 10 tons produce in 24 hours? A little less that 10 tons of ice How many watts are equal to one horsepower? .746 watts What is the velocity of air in an air duct given the rate of flow: 340 cfm, 4.5 square foot duct area V = Q/A V = 340/4. V = 75. How many pounds are in 1-gallon of water? 8.33 lbs. The temperature on a wet-bulb thermometer equals the dry-bulb temperature when A) the air is below freezing B) the air is saturated with moisture C) the air has no moisture D) this can never happen A) the air is below freezing Carbonate deposits from brine on ice cans can be controlled to a great extent by A) adding sodium dichromate to the brine B) increasing the pH to 8 for a period of time C) adding calcium chloride to the brine solution D) decreasing the pH to slightly under 7 for a period of time D) decreasing the pH to slightly under 7 for a period of time What is the purpose of the pressurized glass tank of oil on top of the booster compressor? This tank of oil feeds the mechanical seal on the compressor. It assures that no air will be sucked into the compressor along the shaft. Since a portion of the cylinder is under a vacuum, air can be sucked in along the shaft if the seal leaked. A desireable property of ammonia refrigerant oil is A) high paraffin content B) being free of water C) very low flash point D) all of the above B) being free of water Relative humidity refers to the total moisture content of air. This statement is A) is true B) is false C) is partly true D) defines absolute humidity
