Final Review RMO Exam Questions and Complete Solutions

Final Review RMO Exam Questions and Complete Solutions When instructed to start a reciprocating plant for Air conditioning the first thing to do is? A. TURN ON CHILLED WATER PUMPS AND OPEN THE BYPASS TO LIGHTER LOAD B. INSTALL LARGER FUSE TO TAKE THE INITIAL LOAD, AND THEN TURN ON THE COOLING TOWER FANS C. TURN ON CHILLED WATER PUMP, CONDENSER WATER PUMPS AND COOLING TOWER FANS D. SET THE THERMOSTAT A FEW DEGREES HIGHER - Answer: C. Turn on chilled water pump, condenser water pumps and cooling tower fans The most important reason for using 2 compressors in a cascade system is? A. ACCOMPLISH LOWER TEMPERATURE B. PERMIT THE USE OF INEXPENSIVE LUBRICATING OIL C. AVOID THE NEED FOR VERY HIGH COMPRESSION RATIOS D. DIVIDE THE COOLING LOAD BETWEEN 2 COMPRESSORS - Answer: A. Accomplish lower temperature (most important) Advantage of Forced Draft over Natural Draft is? A. THE POSSIBILITY OF LOWER WATER OUT TEMP B. THERE IS NO DEPENDENCE ON NATURAL WIND VELOCITY C. USE OF A SMALLER TOWER SIZE D. ALL OF THE ABOVE - Answer: D. All of the Above The mechanism sitting above the evaporator is? A. ECONOMIZER B. PURGE UNIT C. AIR BLEED D. PRESSURE RELIEF VALVE - Answer: B. Purge Unit What shaft seal prevents vapor from leaking out of the compressor? A. STUFFING BOX B. ELECTRO-MECHANICAL SEAL C. MECHANICAL SEAL D. ALL OF THE ABOVE - Answer: A. Stuffing Box When will BTU's absorbed by condenser water be the highest? A. LOW CONDENSER TEMPERATURE, LOW CONDENSER WATER TEMPERATURE B. HIGH CONDENSER TEMPERATURE, HIGH CONDENSER WATER TEMPERATURE C. HIGH CONDENSER TEMPERATURE, LOW CONDENSER WATER TEMPERATURE D. LOW CONDENSER TEMPERATURE, HIGH CONDENSER WATER TEMPERATURE - Answer: C. High Condenser temperature, Low Condenser Water temperature Shell and Tube condensers have the advantage of? A. REMOVING HEADS FOR CLEANING THE WATER SIDES OF THE TUBES B. THE REFRIGERANT CONNECTIONS DOES NOT HAVE TO BE DISRUPTED C. USING ACID FOR CLEANING D. BOTH A AND B ARE CORRECT - Answer: D. Both A + B are correct Shell and Tube *Allows for punching tubes without disrupting refrigerant connections* Removing the insulation on the suction line, with the machine room at 85ºF will have what effect? A. FLOODED EVAPORATOR B. STARVED EVAPORATOR C. EXCESSIVE SUPERHEAT D. LOW SUPERHEAT - Answer: C. Excessive Superheat *Boiled refrigerant will pick up more sensible heat if insulation is removed on suction line* The cylinder unloader controls capacity. Is there any other function it performs? A. ASSIST WITH COMPRESSOR SHUT DOWN B. ASSIST WITH COMPRESSOR START UP C. THERE IS NO OTHER FUNCTION D. RELEASES PRESSURE - Answer: B. Assist with compressor start up When the temperature and load increase the RMO is instructed to bring another pump on line. In order to bring a pump on line you would: A. CLOSE BOTH SUCTION AND DISCHARGE B. OPEN BOTH SUCTION AND DISCHARGE C. OPEN SUCTION AND THROTTLE DISCHARGE D. OPEN DISCHARGE BYPASS AND CLOSE SUCTION - Answer: C. Open suction and Throttle discharge A system has a 5 pound pressure drop and is therefor equipped with an external equalizer line. If this line were to disconnect: A. EXCESSIVE SUPERHEAT B. EVAPORATOR WOULD STARVE C. EVAPORATOR WOULD FLOOD D. TEV WOULD NOT FUNCTION - Answer: B. Evaporator would starve *no bulb pressure= no opening force to push needle down and allow refrigerant flow* The metering device used in a condenser is a High Side Float. This float relies on precise amounts of refrigerant to condense. Its main purpose is to: A. CONTROL THE AMOUNT OF WATER IN CONDENSER B. CONTROL THE AMOUNT OF REFRIGERANT IN CONDENSER C. KEEPS A CONSTANT PRESSURE D. KEEPS A CONSTANT TEMPERATURE - Answer: B. Control the amount of refrigerant in the condenser *Metering devices such as Low side float+ high side float control refrigerant flow* How will a hermetic compressor with a low refrigerant charge most likely effect the compressor? A. HEAD PRESSURE WOULD RISE B. COMPRESSOR WOULD OPERATE AT HIGHER TEMPERATURE C. HAVE NO EFFECT ON THE COMPRESSOR D. OIL PRESSURE WOULD RISE - Answer: B. Compressor would operate at higher temperature Suction pressure 18" Hg Vacuum Discharge 8 psig Compression ratio: A. 3.50 B. 2.96 C. 1.75 D. 2.76 - Answer: A. 3.50 Convert both to Psia and divide Psia = (30-18) / 2 = 6 psia Psia= 8 + 14.7 = 22.7 psia 22.7 / 6 = 3.78 : 1 (compression ratio) An oil with Low Viscosity (Internal Friction) would: A. NOT BE USED FOR REFRIGERATION B. BE USED FOR ENGINE/MOTORS C. BE USED FOR AIR CONDITIONING D. BOTH B AND C ARE CORRECT - Answer: A. Not be used for refrigeration *HIGH viscosity is desired* When charging a centrifugal system the valve seat is positioned: A. FRONT SEATED B. BACK SEATED C. CRACKED OFF THE BACK SEAT D. CLOSED - Answer: B. Back seated A system is equipped with a water regulating valve on a reciprocating chiller. Water is entering the condenser at 88ºF. You know there is no scale and the tubes are not covered with film. What can be causing this condition? A. HIGH HEAD PRESSURE B. LOW SUCTION PRESSURE C. WATER VALVE STUCK OPEN D. WATER VALVE STUCK CLOSED - Answer: C. Water (regulating) valve stuck open A water regulating valve is installed in a water cooled condenser. The operating force on this valve is respondent to: A. HIGH SIDE PRESSURE B. CHILLED WATER TEMPERATURE C. CIRCULATING WATER PRESSURE THROUGH THE CONDENSER D. MANUAL OPERATION - Answer: A. High side pressure *Water regulating valve responds to High side pressure* A low pressure refrigeration system has a pinhole in the evaporator. What is the most likely result? A. HIGH HEAD PRESSURE B. FROST AROUND LEAK AREA C. HIGH CONDENSER WATER PRESSURE D. LOW CONDENSER PRESSURE - Answer: A. High head pressure Condenser water pump is cavitating in an R-22 system. Of the following which is the most likely cause? A. AIR LEAKS THROUGH THE PUMP PACKING B. OPERATING AT SUSTAINED HIGH LOADS C. FAULTY COOLING TOWER WATER LEVEL CONTROLLER D. TOO LONG A PERIOD BETWEEN PUMP SERVICING - Answer: C. Faulty cooling tower water level controller If a centrifugal pump operates satisfactorily at full discharge, but loses water flow if throttled, the RMO can assume this is due to: A. WATER HAMMER B. CLOGGED STRAINER IN PUMP INLET C. POOR BEARING LUBRICATION D. AIR LEAKS IN THE PUMP - Answer: B. Clogged Strainer in pump inlet Superheat is beneficial because it protects the compressor against damage from liquid. On the flip side one of the problems associated with superheat is that it: A. NON-CONDENSABLES ARE MORE PRONE TO COLLECT IN THE SYSTEM B. FROST MAY DEVELOP IN THE SUCTION LINE C. IT WILL DECREASE THE CAPACITY OF THE COMPRESSOR AND THE REFRIGERATION MACHINE D. THE COMPRESSOR HEAD PRESSURE DROPS TOO LOW - Answer: C. It will decrease the capacity of the compressor and the Refrigeration Machine *Superheat absorbs additional heat, requiring additional heat to be expelled, increasing work needed by machine* Assuming the machine room is 85ºF unravelling of insulation around the thermal bulb (sensing bulb) will result in: A. ADEQUATE SUPERHEAT B. STARVED EVAPORATOR C. EXCESSIVE SUPERHEAT D. FLOODED EVAPORATOR - Answer: D. Flooded Evaporator *False Load* *Bulb pressure/temp increase, overcomes P1 and P2, sends refrigerant to evaporator* The primary reason for the installation of the crankcase breather is to: A. INCREASE THE COMPRESSOR EFFICIENCY B. TO PREVENT OIL SLUGGING IN THE COMPRESSOR C. KEEP THE SHAFT PACKING LUBRICATED D. TO PREVENT REFRIGERANT FROM ENTERING THE COMPRESSOR SUCTION - Answer: B. Prevent oil slugging in the compressor RMO notices discharge pressure/temperature for a reciprocating compressor refrigeration unit are out of the normal range, but the machine is not cycling. Of the following what may be causing this set of conditions? A. PURGE UNIT OPERATION B. AN EXPANSION VALVE THAT IS OPEN TOO WIDE C. FAULTY COMPRESSOR VALVES D. CONDENSER OPERATION, DIRTY TUBES OR COOLING WATER CONTROL - Answer: C. Condenser operation, dirty tubes or cooling water control Remember: discharge out of normal range, machine not short cycling *When discharge pressure/temperature range is affected, but not cycling times, it is not the valves* What is the maximum percentage of refrigerant that can be stored in a cylinder? A. 75% B. 80% C. 90% D. 100% - Answer: A. 75% *NYC exam. State law (75%) stricter than federal (epa 80%)* RMO is logging readings from a unit. Crankcase temp is low, discharge is low, and suction is high. Of the following what may cause this set of conditions? A. COMPRESSOR CYCLING B. AN EXPANSION VALVE WHICH IS CLOSED TOO MUCH C. AN EXPANSION VALVE WHICH IS OPEN TO WIDE D. FAULTY COMPRESSOR VALVES - Answer: D. Faulty compressor valves Crankcase= low Discharge= low Suction= high *remember two low = valves* Regarding leakage: A. GATE VALVE CAUSES LESS LEAKAGE B. GLOBE VALVES CAUSES MORE LEAKAGE C. ALL VALVES ARE THE SAME D. GATE VALVES CAUSES MORE LEAKAGE - Answer: D. Gate valves cause more leakage Shell and coil condensers have the advantage of: A. REMOVING HEADS FOR CLEANING THE WATER SIDES OF THE TUBES B. THE REFRIGERANT CONNECTIONS DO NOT HAVE TO BE DISRUPTED C. HAS LESS CHANCE OF DEVELOPING LEAKS D. BOTH A AND B ARE CORRECT - Answer: C. Has less chance of developing leaks If a compressor is running fine at full flow, but stops running normally (short cycles) when throttled, this may be due to: A. DIRTY FILTER/STRAINER B. AIR GETTING IN SEALS C. LOW PRESSURE CUT OUT D. HIGH HEAD PRESSURE - Answer: C. Low pressure cutout If unloaders were to fail in the open position, what will most likely occur? A. THE EVAPORATOR WILL STARVE B. CAUSE HIGH SUPERHEAT C. NOT ENOUGH REFRIGERANT TO COIL D. ALL OF THE ABOVE - Answer: D. All the Above If you had 38º in the evaporator, what should your suction pressure be for R-22 A. 66 PSIA B. 66 PSIG C. 76 PSIG D. 76 PSIA - Answer: B. 66 psig Oil flashpoint temperature in the compressor should be: A. LOWER THAN THE HEAT OF COMPRESSION B. HIGHER THAN THE HEAT OF COMPRESSION C. EQUAL TO THE HEAT OF COMPRESSION D. EQUAL TO THE HEAT ABSORBED - Answer: B. Higher than the heat of compression In a 3-stage centrifugal compressor: A. PRESSURE INCREASES WITH EACH STAGE B. IMPELLERS ARE SAME SIZE C. IMPELLERS INCREASE WITH EACH STAGE D. BOTH A AND B ARE CORRECT - Answer: D. Both A + B are correct The reading on the Oil pressure gauge should read: A. 15-30 PSI LOWER THAN SUCTION PRESSURE OF A COMPRESSOR B. 15-30 PSI HIGHER THAN MIDDLE OF THE EVAPORATOR C. 15-30 PSI HIGHER THAN SUCTION PRESSURE OF A COMPRESSOR D. 15-30 PSI LOWER THAN MIDDLE OF THE EVAPORATOR - Answer: C. 15-20 Higher than suction pressure of a compressor Which of the following is an "inline" refrigeration system, which may be used with a centrifugal compressor containing R-123 refrigerant? A. REFRIGERANT RECOVERY B. REFRIGERANT DISPOSAL C. REFRIGERANT RECLAIMING D. REFRIGERANT RECYCLING - Answer: D. Refrigerant Recycling *inline- in cycle- recycle* Bubbles in sightglass are most likely caused by: A. AN OVERCHARGED SYSTEM B. NON-CONDENSEABLE GASES C. LIGHT LOAD ON THE PLANT D. PARTIALLY PLUGGED FILTER/DRIER - Answer: D. Partially plugged filter/drier *loss of liquid seal* Chilled water pump in a R-123 system is cavitating. What is most likely the cause? A. MALFUNCTIONING OF THE WATER MAKE UP FLOAT VALVE B. TOO MUCH TIME IN BETWEEN PUMP SERVICING C. OPERATING AT SUSTAINED HIGH LOADS D. LOWERING THE CHILLED WATER TEMPERATURE - Answer: A. Malfunctioning the water make up float valve Latent heat and refrigeration effect are often listed as refrigerant properties. Refrigeration effect is always lower than the latent heat because: A. HEAT REQUIRED TO COOL THE REFRIGERANT FROM COMPRESSOR DISCHARGE TO EVAPORATIVE TEMPERATURE IS SUBTRACTED FROM LATENT HEAT (Your Answer) B. REFRIGERANT LATENT HEAT IS DIVIDED BY SPECIFIC GRAVITY OF THE REFRIGERANT C. REFRIGERANT CRITICAL TEMPERATURE IS FACTORED INTO THE CALCULATION OF THE REFRIGERATING EFFECT D. REFRIGERANT LATENT HEAT IS DIVIDED BY THE REFRIGERANT CIRCULATION RATE - Answer: A. Heat required to cool the refrigerant from compressor discharge to evaporative temperature is subtracted from latent heat Latent heat - (heat required to cool refrigerant) = refrigeration effect *always lower* Clearance volume: A. AFFECTS COMPRESSOR CAPACITY B. IS THE SPACE THAT TRAPS LIQUID REFRIGERANT C. VARIES, DEPENDING ON COMPRESSOR SPEED D. IS THE SAME ON ALL COMPRESSORS - Answer: A. Affects compressor capacity gauge reads 15 psi. Convert to "hg A. 18 "hg B. 14 "hg C. 20 "hg D. 30.3 "hg - Answer: D. 30.3 "hg Formula 1 : (30-30.3) / 2 = -0.15 psia -0.15 + 14.7= 14.55 psig (closest to 15) Formula 2 : 15 psi- 14.7 = 0.3 psia 0.3 psia = (30-x) / 2 (multiply 2) 0.6 = 30-x (subtract 30) 29.4 "hg = x (closest to 30.3 "hg) External lubrication systems are often used with _________ motors and compressors. - Answer: Open Compression stroke elevation is most equal to: A. Saturation pressure reading B. Discharge pressure gauge C. Suction pressure gauge D. Atmospheric pressure - Answer: C. Suction pressure In a parallel pumping arrangement each pump must develop HP to overcome what without risking motor burnout? A. Differential pressure B. Water flow C. Total System head D. Power factor - Answer: C. Total system head Which type of compressor has spring loaded vanes fixed to a Rotor? A. Rotating vane type Rotary compressor B. Scroll compressor C. Screw type Rotary compressor D. Centrifugal compressor - Answer: A. Rotating vane type Rotary compressor Reduced head pressure will result in ____________ cooling water flow rate Increased or reduced? - Answer: reduced Gaskets in ammonia systems are: A. Copper B. Magnesium C. Aluminum D. Lead - Answer: D. Lead NYC code states that the maximum setting of a systems pressure limiting device should be adjusted to a percentage of the relief valve setting or the high-side working pressure. This percentage is? A. 70% B. 80% C. 90% D. 100% - Answer: C. 90% According to code, a refrigeration system containing 2000 lbs of refrigerant, require exhaust fans with a capacity of? A. 350 Cfm B. 2050 Cfm C. 3500 Cfm D. 2900 Cfm - Answer: D. 2900 Cfm According to code, a refrigeration system containing 600 lbs of refrigerant, require exhaust fans with a capacity of? A. 1275 Cfm B. 1450 Cfm C. 1100 Cfm D. 600 Cfm - Answer: B. 1450 Cfm In regards to code, the installation of a 30 lb, R-12 system, in the lobby of a building: A. May not be installed B. Can be installed with a charge under 15 lbs C. May not be installed in the lobby D. Can be installed - Answer: D. Can be installed Sweat joints, in copper tubing, used for a group 2 refrigerant must be: A. Factory bent at a 90º angle B. Soldered C. Brazed D. Soldered or brazed - Answer: C. Brazed A pressure limiting device controls: A. Evaporator B. Condenser C. Compressor D. Relief Valve - Answer: C. Compressor Liquid level gauge valves, except two types (list them), shall be equipped with the following: A. calibrating references B. Drain assemblies C. Automatic shut-off valves D. Vents - Answer: *Except "Bulls eye" or "reflex type" * C. Automatic shut-off valves With reference to minimum requirements for refrigerant pipe and tubing, which of the following is most nearly correct? A. Standard soft annealed copper tubing use for refrigerant piping shall not exceed one half inch. B. Joints in copper tubing, containing group 2 refrigerants, should be soldered C. Standard IPS copper, brass pipe and tubing, shall not be less than 80% copper D. Standard wall steel or wrought iron pipe may be used for refrigeration liquid lines, one inch or smaller - Answer: C. Standard IPS copper, brass pipe and tubing, shall *not be less than 80% copper* A sign on the wall of a refrigeration plant can omit: A. Number of condensers B. Pounds of refrigerant C. Name of installer D. Horsepower of prime mover - Answer: A. Number of condensers In a Class T Machine room, All pipes piercing the wall and ceiling should be tightly _________ and have fire resistant construction of _______________. - Answer: Tightly sealed Fire resistant construction of not less than 1 hour A soldered joint is a gas tight joint obtained by the joining of metal parts with metallic mixtures of allows that melt at temperatures below: A. 600º and above 250º B. 800º and above 300º C. 925º and above 350º D. 1000º and above 400º - Answer: C. 925º and above 350º The maximum permissible quantity of refrigerant in a R-22 direct system is 22 pounds per 1000 cu. Ft. of humanly occupied space. When serving individual stories, the amount used is determined by: A. Story with largest volume B. Story with smallest volume C. Average of the stories D. The aggregate of the stories - Answer: B. Story with smallest volume Which indicates the maximum permissible quantity of R-744 that can be used in a direct system? (lbs per 1000 cu ft) A. 20 lbs/ 1000cu ft B. 31 lbs/ 1000cu ft C. 6 lbs/ 1000 cu ft D. 11 lbs/ 1000 cu ft - Answer: D. 11 lbs/ 1000 cu ft Standard soft anneal copper tubing used for refrigerant piping erected on the premises shall not be used in sizes larger than? A. 3/4 in B. 1/2 in C. 1 in D. 7/8 in - Answer: D. 7/8 in According to ASHRAE standard, Discharge of pressure relief valve or fusible plug must be installed: A. 15 Feet above the ground level, and not less than 20 feet from any window, ventilation opening or exit in any building B. 20 Feet above the ground level, and not less than 15 feet from any window, ventilation opening or exit in any building C. 15 Feet above the ground level, and not less than 15 feet from any window, ventilation opening or exit in any building D. 20 Feet above the ground level, and not less than 20 feet from any window, ventilation opening or exit in any building - Answer: A. 15 Feet above the ground level, and not less than 20 feet from any window, ventilation opening or exit in any building When a rupture member is used in parallel with a relief valve it shall operate/burst at which of the following pressures: A. not to exceed 100% design working pressure B. not to exceed 10% design working pressure C. not to exceed 90% design working pressure D. not to exceed 20% design working pressure - Answer: D. not to exceed 20% design working pressure Dial of a pressure gauge, installed on the high side, must be able to read: A. 1.2 times designed pressure minimum B. 1.5 times high side pressure minimum C. 150% low or high side pressure minimum D. 150% design working pressure minimum - Answer: D. 150% design working pressure minimum Smoke detector, located in discharge side of air distribution system, when activated should be followed by: A. Associated fans automatically activated B. Shut down of fans in affected floor C. Increase of fan speed D. Associated fans automatically stopped - Answer: D. Associated fans automatically stopped Machine room Safety Standards were established by: A. ARI-700 B. ARI-740 C. ASHREA 30 D. ASHREA 15 - Answer: D. ASHREA 15 Refrigerant Safety Standards were established by: A. ARI-700 B. ARI-740 C. ASHREA 34 D. ASHREA 15 - Answer: C. ASHREA 34 Soft copper tubing, erected on the premises and containing other than Group 1 refrigerants must be protected by? A. Clamps to wall/ ceiling B. Shortened tubbing length to reduce potential hazard C. Rigid/flexible metal enclosure D. Outer casing made of Iron - Answer: C. Rigid/flexible metal enclosure Maximum permissible number of pounds of group 2 refrigerant for an indirect system in a class T machine room is? A. 300 lbs B. 20% of charge C. 1000 lbs D. No limit - Answer: D. No limit Ducts that remove gas from machine rooms, using R-12, shall have the inlet to the ducts located where (according to code) : A. Near the floor next to the equipment B. Near the ceiling above the equipment C. Midway between the ceiling and floor D. outside the machine room door on the ceiling - Answer: A. Near the floor next to the equipment Which indicates the maximum permissible quantity of R-12 that can be used in a direct system? (lbs per 1000 cu ft) A. 20 B. 31 C. 6 D. 11 - Answer: B. 31 lbs per 1000 cu. ft. Refrigerant Leak test pressure for an ammonia system? A. High 300psi / low 150psi B. High 30psi/low 30 psi C. High 235psi/low 140 psi D. High 1000psi/low 750 psi - Answer: A. High 300psi / low 150psi Condensing unit includes which two major components? - Answer: Condenser and Compressor Which of the following components make it possible for a fusible plug to relieve excess pressure? A. Spring pressure B. Low temperature fuse C. Predetermined temperature fusible member D. Predetermined pressure set according to system operation - Answer: C. Predetermined temperature fusible member * will burst at 275º * Fusible plug can be installed: A. Below the Liquid line B. On the evaporator C. Above the Liquid line D. Both A + C - Answer: D. Both A + C Flame producing apparatus located in a MER with group 1 refrigerant A. Cannot be used B. Flame must be enclosed and vented to open air C. Must be 25 feet from refrigeration machine D. Can be used with flame not exceeding 500º - Answer: B. Flame must be enclosed and vented to open air Which of the following is not a requirement of a Type T Machine Room? A. Tight fitting doors B. Means of mechanical ventilation C. One-hour fire resistant construction D. Minimum of 2 doors, with 5 square feet of clearance - Answer: D. Minimum of 2 doors, with 5 square feet of clearance Maximum amount of refrigerant stored in a machine room: A. No limit B. 300 lbs C. 15% annual charge lost D. 20% of normal charge - Answer: B. 300 Lbs (best answer) *300 lbs or 20%* but *300 is always the limit* 20% is higher than 300 it is ignored Brazed joint is gas tight joint obtained by the joining of metal parts with metallic mixtures of alloys that melt at temperatures higher than: A. 600º B. 800º C. 1000º D. 999º - Answer: C. 1000º Rated discharge capacity of relief valve or fusible plug is expressed as: A. Lbs of refrigerant per minute B. Btu's C. Lbs of pressure per minute D. Lbs of air per minute - Answer: D. Lbs of air per minute Which of the following describes the setting that a pressure relief device is designed to function at? A. 20% design operating pressure B. 2x the bursting pressure C. Vessels design pressure D. 110% vessels design pressure - Answer: C. Vessels design pressure Which voltage is used in control systems? A. 12 V B. 440 V C. 208 V D. 24 V - Answer: D. 24 V A mechanism for automatically stopping the operation of the "pressure imposing element" is a: A. Pressure Relief Device B. Fusible Plug C. Thermostat D. Pressure limiting device - Answer: D. Pressure limiting device Solenoid valve in basic control systems, will be in what position when current flows through? A. Closed B. Open C. Half Way D. Any point between fully open or fully closed - Answer: B. Open *solenoid in basic control system is NC* Which of the following does not control flow to the Evaporator? A. Capillary tube B. Solenoid Valve C. High-side Float D. TEV - Answer: C. High-side float If a solenoid closes when energized it is ______________. - Answer: Normally open What determines when the electrical contact inside of thermostat closes? A. Setpoint B. Ambient temperature C. Pressure relief setting D. Pressure limiting device - Answer: A. Setpoint Short cycling can cause what problem? A. Low evaporator pressure B. Strain on condenser C. Increased heat of compression D. Motor burnout - Answer: D. Motor burnout What could cause refrigeration circuit to short cycle? A. Shortage of refrigerant B. System overcharge C. Restriction in liquid line D. Short circuit at motor windings - Answer: A. Shortage of refrigerant *shortage = short cycle* If a thermostat controlling compressor did not have a wide enough differential the probable result would be: A. Oil not returning to compressor B. Shut down on High pressure cutout C. Shut down on Low pressure cutout D. Long operating cycle - Answer: C. Shut down on Low pressure cutout Which of the following can cause short cycling? A. System overcharge B. Restriction in liquid line C. Improper adjustment of LP cutout D. Short circuit at motor windings - Answer: C. Improper adjustment of LP cutout Maximum setting of Pressure limiting device may be adjust to, but not exceed: A. 85% system operating pressure B. 90% setting of pressure relief device C. 80% setting of pressure relief device D. 20% setting of pressure relief device - Answer: B. 90% setting of pressure relief device What will occur if tubing that connects water regulating valve to the system becomes obstructed? A. Low suction pressure B. Possible motor burnout C. High Head pressure D. Decrease in condenser water temperature - Answer: C. High head pressure *Less water = High head pressure* How does reduced head pressure affect the operation of a water regulating valve? A. Increased cooling water flow B. Reduced cooling water flow C. Slow response time with variable load D. No change - Answer: B. Reduced cooling water flow Bellows of water regulating valve should be connected to which of the following? A. return water side of condenser B. Liquid line C. Bottom of evaporator shell D. Top of condenser shell - Answer: D. Top of condenser shell Which of the following has the highest operating settings? A. High pressure cutout B. Spring loaded relief valve C. Water regulating valve D. Cut- in pressure - Answer: B. Spring loaded relief valve A low pressure controller has adjustments for a "cut-in" value and "differential". At what pressure does the compressor cycle off? A. Pressure equal to "cut-in" B. Pressure above "cut-in" C. Pressure below "cut-in" D. Pressure corresponding to load on evaporator - Answer: C. Pressure below "cut-in" Which of the following has the highest rating or setting? A. Vessel design pressure B. High side operating pressure C. Bursting pressure D. Relief valve setting - Answer: C. Bursting pressure Which of the following is designed to protect the compressor? A. Fusible plug B. High pressure cut-out C. Spring loaded relief valve D. Rupture disc - Answer: B. High pressure cut-out *Safety device* Pressure limiting device *protects from pressure imposing element* What is the purpose of the lead seal on a spring loaded relief valve? A. Display date and lot number B. Prevent removal of the valve operator C. Prevent readjustment of valve setting D. Display operating settings and refrigerant type - Answer: C. Prevent readjustment of valve setting Which of the following values fall somewhere between the cut-in and cut-out settings of a low pressure controller? A. Atmospheric pressure B. Setting of High pressure cut-out C. Condenser discharge pressure D. Normal operating evaporator pressure - Answer: D. Normal operating evaporator pressure Is the refrigerant in Lithium bromide absorption system Lithium bromide or Water? - Answer: Water Flow rate of aqua ammonia at the aqua-ammonia (refrigerant) pump must be equal to what flow rate? - Answer: Aqua-ammonia at weak-liquor regulating valve Separating of High pressure ammonia vapor from aqua-ammonia solution takes place at which component? - Answer: Generator To vary capacity on absorption system from 50% to 100%, operator should do what two things? - Answer: 1. Increase steam to generator 2. reset expansion valve In absorption system the solution is made stronger in what component? - Answer: Absorber A counter flow heat exchanger in an absorption system is located between the? A. Condenser and liquid cooler B. Analyzer and rectifier C. Generator and absorber D. Absorber and pump - Answer: C. Generator and Absorber *Weak heats Strong* Remember: Weak hate strong- Weak heats strong Lowest possible chilled water temperature leaving evaporator for lithium bromide? Lowest operating temperature? - Answer: Lowest possible: 33º Lowest operating: 38º Rectifier is designed like a ______________ heat exchanger - Answer: closed type Analyzer's flow of ammonia vapor in relation to strong liquor can be described as? A. Cross flow B. Parallel flow C. Counter flow D. Diagonal flow - Answer: C. Counter blow Remember: analyzer has baffles, baffles COUNTER the FLOW The strength of the strong liquor in an absorption system decreases as the: A. Expansion valve is opened B. Condenser pressure decreases C. Evaporator load increases D. Evaporator load decreases - Answer: D. Evaporator load decreases Remember: Strong liquor becomes stronger if it carries heavier load Crystallization in an absorption cycle is most frequently caused by? A. Air in the machine B. Decrease in the capacity of the condenser C. Cold condenser water temperature D. Low concentration of Lithium Bromide - Answer: C. Cold condenser water temperature Which piping would not be chosen for ammonia or aqua-ammonia solutions? A. Black steel B. Stainless steel C. Galvanized steel D. Wrought iron - Answer: C. Galvanized steel Anhydrous indicates refrigerant that has ______________. - Answer: No water Which of the following systems is most likely to incorporate a purger? A. Ammonia absorption B. Lithium Bromide absorption C. Ammonia reciprocating compression D. Ammonia centrifugal compression - Answer: B. Lithium Bromide absorption *water is refrigerant which can carry air* How many times is an absorption system separated from the high and low side? - Answer: 3 times Strong solution exiting the absorber has a strength of approximately ____% and the weak solution ___% - Answer: Strong 28% ammonia Weak 22% ammonia Which of the following best describes the process that makes it possible to transfer low pressure vapor from the evaporator to the absorber in an absorption system? A. Mechanical B. Thermodynamic C. Chemical D. Electrostatic - Answer: C. Chemical Type of coil located in the absorber of an absorption system? - Answer: Cooling water coil Which of the following cannot be used as a desiccant in a refrigeration cycle? A. Drierite B. Calcium oxide C. Activated Alumnia D. Soda lime - Answer: D. Soda lime Which of the following best describes the function of an accumulator? A. Similar to that of an analyzer in an absorption system B. Prevent solids from entering the compressor C. Prevent liquid from entering the compressor D. Increase refrigeration effect - Answer: C. Prevent liquid from entering the compressor SUCTION accumulator- suction line-compressor cannot have moisture A scale trap is installed on the suction line to collect foreign matter. This component is most effective when: A. The plant is new B. Efficiency decreases C. The plant is old D. The plant has been shut down for a period of time - Answer: A. The plant is new Which of the following arranges liquid line components in the correct order? A. Solenoid, drier, sightglass, TEV B. Drier, sightglass, solenoid, TEV C. King valve, drier, solenoid, sightglass, TEV D. King valve, drier, sightglass, solenoid, TEV - Answer: C. King valve, drier, solenoid, sightglass, TEV A silica gel dryer that has become moisture laden may be reactivated by heating the desiccant for how many hours and at what temperature? A. 2 Hours or more at 450 degrees B. 2 Hours or more 300 degrees C. 4 Hours or more 450 degrees C. 4 Hours or more 400 degrees - Answer: C. 4 Hours or more 450 degrees What is the reason for insulating the suction line of a compression system? A. Prevent loss of refrigeration effect B. Reduce compressor strain from absorbing sensible heat C. Increase circulation of oils D. Prevent condensation from forming on cold metal surface - Answer: D. Prevent condensation from forming on cold metal surface Muffler installed between the ___________ and ____________ - Answer: Compressor and condenser *As close to compressor as possible* Primary reason for running the suction line and liquid lines in physical contact with one another? A. Separate oil from refrigerant in suction line B. Reduce installation cost C. Superheat liquid refrigerant before the TEV D. Sub-cool the refrigerant in liquid line - Answer: D. Sub-cool the refrigerant in liquid line 3 things removed by filter drier in liquid line: - Answer: 1. Acid 2. Moisture 3. Heavy particles Which of the following best describes the temperature of a sub-cooled refrigerant? A. Above the saturation temperature B. At the saturation temperature C. Below the saturation temperature D. Above the condensing temperature - Answer: C. Below the saturation temperature Loss of liquid seal (seen as bubbles in the sightglass) indicates: A. High head pressure B. Low head pressure C. Shortage of refrigerant D. Overcharge of refrigerant - Answer: C. Shortage of refrigerant What is the process causing refrigerant to absorb additional heat energy as it travels through the compressor? A. High head pressure B. Heat of compression C. High compressor temperature D. Ambient heat absorption - Answer: B. Heat of compression Superheat = ______________ temperature from the ___________ temperature. A. Measured, saturation B. Saturation, Measured - Answer: B. Saturation, Measured *Superheat= measured - saturation* Water tube leaks low pressure chiller use ______________ testing. - Answer: hydrostatic Which of the following best describes Shell and Tube type evaporator? A. Full of liquid refrigerant with a gas space at the top B. Full of gas with a thin layer of liquid at the bottom C. Refrigerant in Tubes, Water in Shell D. Shell full of chilled water up to top row, with clearance space for vapor - Answer: A. Full of liquid refrigerant with a gas space at the top *Refrigerant in shell, Water in tubes* DX system is fitted with baffles, the main purpose of baffles are to _____________________. - Answer: Direct air flow Shell and Tube evaporator is: A. Refrigerant in tubes, water in shell B. Refrigerant in shell, water in tubes C. Refrigerant in coil, water in shell D. Refrigerant in shell, water in coil - Answer: B. Refrigerant in shell, water in tubes R-22 approximate chilled water temperature being supplied from system is ____ºF - Answer: 45º F What will cause evaporator coil to have the top frosted, and bottom completely dry? A. Evaporator operating normally B. Evaporator is flooded C. Shortage of refrigerant D. Water in the system - Answer: C. Shortage of refrigerant In a compression system with a continuously running compressor, How will the suction pressure be affected as the evaporator load decreases? A. Suction will increase B. Suction will decrease C. Suction will remain constant D. First decrease, than gradually return, and remain constant - Answer: B. Suction will decrease If pleated media filter upstream of an evaporator becomes clogged, how will this affect the system? A. High head pressure at the compressor B. High suction pressure at the compressor C. Low suction pressure at the compressor - Answer: C. Low suction pressure at the compressor Shell and Tube evaporator is equipped with eliminators near the top of the shell. Which best described what they prevent? A. Oil from entering suction line B. Gas entering suction line C. Moisture carry-over D. Liquid entering suction line - Answer: D. Liquid entering suction line Evaporators use ____________ to transfer heat. - Answer: Conductive heat transfer Heat is conducted *from air or water TO refrigerant* *refrigerant absorbs heat* Saturation pressure in Evaporator can be used to determine: A. Chilled water returning from the building B. Chilled water being supplied to the building C. Cooling tower efficiency D. System efficiency - Answer: B. Chilled water being supplied to the building Fins on DX coil increase ___________________ which increases heat transfer. - Answer: coil surface Positive displacement: A. Decreases volume, increases pressure B. Decreases pressure, Increases Volume - Answer: A. Decreases volume, increases pressure Non-Positive displacement: A. Decreases volume, increases pressure B. Decreases pressure, Increases Volume C. Moves large volume, Decreases pressure D. Moves large volume, Increases pressure - Answer: D. Moves large volume, Increases pressure Double acting compressor has which characteristic? A. Produces discharge at one end of the cylinder B. Produces discharge at both ends of the cylinder C. Produces suction and discharge at both ends of the cylinder D. Produces suction on alternate strokes - Answer: D. Produces suction on alternate strokes Modern compressors use what material as their shaft seals? A. Lead B. Copper and packing C. Low friction plastics D. Packing glands - Answer: B. Copper and packing Purpose of a shaft seal on a compressor, with a suction pressure of 45 psi, is to keep: A. Air from entering B. Air and moisture from entering C. Oil from escaping D. Refrigerant and oil from escaping - Answer: D. Refrigerant and oil from escaping Positive displacement compressor _______________ volume. - Answer: Reduces Crankcase pressure is closest to _____________ pressure. - Answer: evaporator Compressor provides _____________ pressure needed to circulate the refrigerant. - Answer: differential Which compressor design is suction gas compressed between rotating gears (helical lobes) after having entered the compressor through a sliding vane type capacity control valve? A. Scroll compressor B. Rotating vane compressor C. Stationary single blade compressor D. Screw compressor - Answer: D. Screw compressor Which compressor is known for the smallest displacement? A. Centrifugal B. Screw C. Rotary D. Scroll - Answer: C. Rotary Pressure of centrifugal compressor is determined by: A. Economizer controls B. Impeller tip speed C. Position of vane controls D. Refrigerant type - Answer: B. Impeller tip speed Compressor valves that require the most clearance space is: A. Ribbon Valve B. Ring Plate C. Poppet valve D. Feather valve - Answer: C. Poppet valve TEV are usually rated by: A. Btu's per minute B. Tons of water C. Tons of refrigeration D. Cfm - Answer: C. Tons of refrigeration TEV controls the _________________ to the evaporator and tries to maintain a constant ______________ - Answer: Flow of refrigerant (not pressure/temperature of evaporator) Maintains constant superheat temperature Sensing bulb located Directly after the valve would result in: A. Expansion valve will flood the coil B. Orifice of valve will freeze in open position C. Will starve the coil D. Increase in suction pressure - Answer: C. Will starve the coil Suction vapor, with properly installed sensing bulb, should leave the coil of the evaporator: A. 5-10 degrees superheated B. 15 degrees superheated C. Saturated D. Partially saturated - Answer: A. 5-10 degrees superheated TEV's sensing bulb is clamped to the midpoint of the evaporator. How will this affect the coil operation? A. Air will be properly conditioned B. Air will be unconditioned C. Decrease in superheat D. Excessive superheating - Answer: D. Excessive superheating Maximum Operating pressure vapor charged sensing bulb is ____ psiG - Answer: 55 Setting 10º superheat means vapor passing sensing bulb (remote bulb) will be 10 degrees: A. Above the temperature of the evaporating refrigerant B. Below the temperature of the evaporating refrigerant C. Above the temperature of the surrounding Ambient air D. Below the temperature of the surrounding Ambient air - Answer: A. Above the temperature of the evaporating refrigerant When noticing an Increase in superheat, an RMO can most likely assume what is the cause? A. Partially blocked valve orifice B. Unraveling of insulation protecting TEV valve C. Non-condensables present D. Overcharge of refrigerant - Answer: A. Partially blocked valve orifice Capillary line was ruptured, resulting in charge from thermal bulb being lost. Under this condition the Expansion Valve will: A. Remain fully open B. Remain fully closed C. Hunt consistently D. Switch to external equalizer - Answer: B. Remain fully closed *No bulb pressure = no opening force* A thermostatic expansion valve can be rated in terms of: A. Factory superheat setting B. Operating superheat C. Vapor free Saturated liquid entering the valve D. Formation of flash gas - Answer: C. Vapor free Saturated liquid entering the valve Of the following refrigerant distributors, which does not require an external equalizer line? A. Centrifugal type B. Manifold type C. Venturi type D. Pressure drop type - Answer: B. Manifold type Superheating protects the compressor from liquid damage. What is the problem associated with excessive superheating? A. Non-condensibles are more prone to enter system B. Frost may develop on suction line C. Decreased Evaporator Capacity D. Head pressure drops too low - Answer: C. Decreased Evaporator Capacity Refrigerant distributor is most often used with ___________________ cooling coils. - Answer: Direct expansion Superheating protects compressor from liquid damage. Would would the RMO visually notice if there was liquid refrigerant at the compressor suction? A. Head pressure on gauge dropping too low B. Decreased capacity of the system C. Presence of non-condensibles D. Frost on the suction line - Answer: D. Frost on the suction line When a TEV is required for wide temperature ranges, what type of sensing bulb should be used? A. Gas charge B. Gas cross charge C. Liquid charge D. Liquid cross charge - Answer: D. Liquid cross charge *vapor/ vapor cross has MOP of 55 psi* Flash gas at metering device reduces: A. Temperature B. Pressure C. Both A + B D. Volume - Answer: C. Both A + B TEV Superheat spring did not exert sufficient force: A. Starve Evaporator B. Flood Evaporator C. No change D. Damage to bulb - Answer: B. Flood Evaporator Broken external equalizer line: A. Loss of charge in TEV B. Evaporator will starve C. Loss of total charge D. Evaporator will flood - Answer: C. Loss of total charge Operating superheat is produced by ___________ superheat and ___________ superheat - Answer: Static and Opening superheat Factory setting of TEV is closest to _____ºF to _____ºF - Answer: 8ºF to 12ºF *Look for highest range, closest to 10 degrees* Insulation around bulb unravels at 85º in machine room: A. Evaporator will starve B. Evaporator will flood C. Evaporator will starve, creating excessive superheat D. 8-12º Superheat will be maintained despite load - Answer: B. Evaporator will flood *false load = flood* What can cause High suction pressure, assuming everything is operating normally: A. Dirty condenser tubes B. TEV wide open C. Faulty compressor valves D. Oil logged evaporator - Answer: B. TEV wide open *Maximum load* Increase in superheat could possibly be caused by: A. Unraveling of insulation on suction line B. Location of thermal bulb C. High head pressure D. Non-condensables - Answer: B. Location of thermal bulb When using High-side float, what does frost on the suction line indicate? A. Recharging of refrigerant is required B. Leak in suction line C. Excess of refrigerant D. Contaminants have entered the system - Answer: C. Excess of refrigerant *High side Float relies on precise amount, excess refrigerant in evaporator means low superheat* Which of the following has a direct relationship to the amount of refrigerant metered into the evaporator? A. Sensing bulb location B. Desired coil temperature C. Type of sensing bulb charge D. Pressure drop across the coil - Answer: A. Sensing bulb location Adjusting factory setting of TEV will affect amount of refrigerant supplied to the evaporator. What other condition will be altered? A. Suction pressure B. Head pressure C. Superheat D. Compressor cycling time - Answer: C. Superheat If the evaporator does not respond to adjustments of the expansion valve, it may be due to: A. Liquid in the receiver B. Clogged equalizer line in the crankcase C. Oil logged evaporator D. Compressor log - Answer: C. Oil logged evaporator *Less heat transfer, pipes are coated* Entire evaporator coil is frosted, except the bottom rows: A. Incorrect adjustment of dual pressure controller B. Coil is being flooded C. Water is present in refrigerant D. Coil is being starved - Answer: B. Coil is being flooded Dirty DX Coil will have the same effect as which of the following: A. Dirty media filter B. High load conditions C. Metering device wide open D. Under-sized coil - Answer: A. Dirty media filter Excessive cycling, crankcase temp high, discharge pressure low, suction pressure high: A. Expansion valve open to wide B. Dirty condenser tubes C. Faulty compressor valves D. Purge unit not operating - Answer: C. Faulty compressor valves Vertical single acting compressor, loud pounding on start up caused by: A. Broken wrist pin B. Broken shaft bearing C. Piston slap D. Overcharge of oil in system - Answer: D. Overcharge of oil in system Compressor operated with suction valve closed, Discharge open, _______________ may be drawn into the system. - Answer: Non-condensables Vertical single acting compressor has trunk type pistons. If the oil rings leaked a possible result would be: A. Pounding on start up B. Decreased capacity C. Compressor starts slower, then speeds up D. Increased head pressure - Answer: B. Decreased capacity Systems cooling tower not operating as designed would result in: A. Rusted tubes B. High head pressure C. System in constant need of purging D. Blown rupture disk - Answer: B. High head pressure Of the following, which would not cause high discharge (head) pressure? A. Gas in liquid line B. Overcharge of liquid refrigerant C. Condenser too small D. Insufficient cooling water - Answer: A. Gas in liquid line (caused by loss of liquid seal) Air cooled package air conditioning unit is operating with dirty condenser filters. This condition would result in: A. Low suction pressure at the compressor B. High suction pressure at the compressor C. High head pressure at the compressor D. Hot liquid line at the compressor - Answer: C. High head pressure at the compressor Liquid seal in receiver is lost you will have: A. Condensing hot vapor entering liquid line and evaporating B. Non- condensed hot vapor in the liquid line C. Condensed liquid refrigerant in the compressor D. Condensed liquid refrigerant will remain in the receiver - Answer: B. Non- condensed hot vapor in the liquid line Obstructed, partially blocked liquid line may cause: A. High temperatures between blockage and metering device B. High temperatures between receiver and blockage C. Frost between blockage and metering device D. Frost between receiver and blockage - Answer: C. Frost between blockage and metering device Liquid refrigerant at compressor suction would have ______________ on the suction line. - Answer: Frost Insufficient amount of oil returning to compressor can be caused by: A. Air in the system B. Velocity of refrigerant is too low C. Medium pressure drops in evaporator D. Small load variations in the system - Answer: B. Velocity of refrigerant is too low A condensing unit running R-12 is overcharged. How will this affect the system? A. High side pressure will increase B. Suction and Discharge pressure will increase C. Capacity will decrease D. Capacity will increase - Answer: B. Suction and discharge pressure will increase Which of the following will cause a compressor to short cycle? A. Shortage of refrigerant B. Malfunctioning solenoid valve C. Insufficient Capacity D. Incorrect adjustment on the low pressure cutout - Answer: A. Shortage of refrigerant When bubbles are noticed on the sight-glass installed just before the Expansion valve, this is an indication that: A. Non-condensables are in the receiver B. The purger is not functioning C. Air has leaked into the system D. There is a shortage of refrigerant - Answer: D. There is a shortage of refrigerant *loss of liquid seal* If the liquid line is warmer than usual this is an indication that: A. There is an overcharge of refrigerant B. There is a shortage of refrigerant C. The receiver is full of liquid D. The head pressure is high - Answer: A. There is an overcharge of refrigerant If the belt that drives the motor is too tight, which of the following may result? A. The motor and compressor would slow down B. The unit would run normally C. The capacity of the compressor will increase D. The motor will overheat - Answer: D. The motor will overheat *Amperage will increase if belt is too tight* Because a 3 phase electric motor is considered a "balanced electrical load" there must be equal voltage across each winding. How will an unbalance power source affect the operation of the motor? A. Reduce RPM B. Incorrect Piston rotation C. Reduced motor Horsepower D. Motor will overheat - Answer: D. Motor will overheat Failure to maintain adequate water treatment in condenser water system can result in? A. Lower refrigeration effect B. Lower cost per ton of cooling C. High suction pressure D. High head pressure - Answer: D. High head pressure *bad water = high head* Which of the following will not cause an excessive loss of water from the cooling tower? A. Displacement eliminators B. Uneven operation of spray heads C. Reduced airflow D. Defective or Dirty Fill - Answer: C. Reduced airflow RMO realizes that the water is overflowing from a cooling towers basin. Which of the following is likely to resolve this situation? A. Adjustment of the cold water valve upstream of the tower B. Adjustment of the make-up water assembly C. Reducing the condenser water pump flow rate D. Clean tower fill - Answer: B. Adjustment of the make-up water assembly Cooling tower is being brought online after the replacement of a defective motor. After the start up leaving water temperature from the tower is substantially higher than its normal operating value. Which of the following may be responsible for this? A. Blocked spray heads B. Incorrect rotation of the fan C. Displaced fill D. Dirty condenser water strainer - Answer: B. Incorrect rotation of the fan A cooling tower is designed to operate through winter conditions. Which of the following will prevent excessively cold water from being delivered to the condenser? A. Heat tracing of pipe at roof level B. Reduce condenser water flow rate C. Add glycol to the water D. Cycle the cooling tower fan - Answer: D. Cycle the cooling tower fan Condenser water system has 3 pumps in parallel. If the check valve on any of these pumps is not seating properly what will occur? A. Pump motor will be damaged on start up B. Condenser pressure will rise C. Reduced condenser water flow D. There will be reversed flow on pump start up - Answer: C. Reduced condenser water flow A misalignment between a pump and driver shaft can cause excessive vibration and shorter seal life, what other condition can arise from this problem? A. Shorter bearing life B. Reduction in flow rate C. Decreased pump head D. Incorrect motor speed - Answer: A. Shorter bearing life Backwards rotation of a pump impeller can be caused by reversed polarity of a three phase motor. Correct rotation can be confirmed by referring to the arrow embossed on the pump casing. Which of the following conditions would suggest that a pump was running backwards? A. Higher pump head B. Increased GPM C. Lower pump head D. Overheating of motor - Answer: C. Lower pump head If pump head, developed by centrifugal, is less than the calculated "total system head" than which of the following will take place? A. Net increase of condenser water temperature B. Pump priming needed C. Reverse flow through pump D. Insufficient flow to condenser - Answer: D. Insufficient flow to condenser *will not overcome differential pressure needed to move water* Presence of air in a piping system will affect, if not completely prevent the flow of water. Opening of the petcock on the pump casing will vent air directly from the body of the pump. What other location may need to be vented as well? A. All horizontal lengths of piping B. Piping directly adjacent to the pump C. Heat exchangers D. All system high points - Answer: D. All system high points An evaporator pressure regulator valve is installed so that the two evaporators can operate at different temperatures. If the EPR gets stuck in the open position what will occur? A. Evaporator would operate at the about the higher temperature B. Capacity would go down C. Capacity would increase D. Evaporator would operate at about the lower temperature - Answer: D. Evaporator would operate at about the lower temperature If a tube type sightglass on a receiver was to break which of the following would be a likely result? A. Total Loss of refrigerant B. Loss of refrigerant from the receiver only C. Loss of refrigerant from the sightglass only D. Air would enter the system - Answer: C. Loss of refrigerant from the sightglass only Solution of inhibited hydrochloric acid is used to _____________________. - Answer: Clean Shell and Coil condensers How will low condenser pressure affect the system? A. Less refrigerant will be liquified B. System will shut off on low pressure cutout C. Evaporator will not be fed properly D. Frost will form on suction line and compressor inlet - Answer: C. Evaporator will not be fed properly Evaporative condensers save how much water? (Percentage) - Answer: 85-90% Potassium-permanganate is used in ___________________. Why? - Answer: Spray ponds to kill algae Is head pressure higher in an air-cooled system or water-cooled system? - Answer: Air-cooled Double pipe condenser: Is refrigerant on the inside pipe or outside pipe? - Answer: outside pipe The rate of heat transfer in a condenser will: A. Increase as the velocity of the water in the tubes increases B. Show only a small increase if the tubes are descaled C. Increase with a lower mean average condenser water temperature D. Increase as the wet bulb temperature increases - Answer: C. Increase with a lower mean average condenser water temperature *average condenser water temperature lower, more heat will be expelled* Vertical shell and tube condenser has what kind of water box? - Answer: No water box Water leaving a horizontal shell and tube condenser is usually: A. Somewhat warmer than the discharge gas B. The same temperature as the discharge gas C. A little cooler than the discharge gas D. the same temperature as the cooling water - Answer: C. A little cooler than the discharge gas *allows refrigerant to expel heat* *heat energy moves from hot to cold* Operation of a spray pond and evaporative condenser are _______________. - Answer: Similar What type of condenser can be used without water during winter months? A. Shell and Coil B. Atmospheric type C. Vertical shell and tube D. Submerged - Answer: B. Atmospheric type Heat rejected from a condenser is what type? Latent or sensible - Answer: Latent and sensible heat Both evaporative condensers and evaporators contain eliminators. What is the purpose of these eliminators for each? - Answer: Evaporative Condensers Eliminators: *prevent moisture carry over* Evaporators Eliminators: *prevent liquid from entering suction line* Electric expansion valve used what kind of power? A. 6 volt AC or DC B. 12 volt AC C. 18 volt DC D. 24 volt AC or DC - Answer: D. 24 volt AC or DC If an AEX is mistakenly installed on a variable load system, what is likely to occur when the valve experiences high load? A. System will operate as normal B. Compressor will be damaged C. Evaporator will be starved D. Evaporator will be flooded - Answer: C. Evaporator will be starved *will not recognize/ adjust to increase in load and will not send more refrigerant* Ball float on a low side float is punctured, what will occur? A. Suction pressure would rise B. Head pressure would rise C. Suction pressure would fluctuate D. Compressor would stop immediately - Answer: A. Suction pressure would rise AEX relies on what two pressures? - Answer: Evaporator pressure (always closing) and Spring pressure (opening) Metering device with requires "critical charge" ? - Answer: High side float Where is the metering devices orifice located? - Answer: At the valve's seat Which of the following metering devices have no means of adjustment? A. TEV B. AEX and Capillary Tube C. AEX and orifice plate D. Capillary tube and orifice plate - Answer: D. Capillary tube and orifice plate Horizontal shell and tube cooler is equipped with a float mechanism to control the refrigerant's liquid level in the shell of the cooler. If the equalizer line at the top of the float chamber should become obstructed, which of the following is likely to take place? A. Compressor will overspeed B. Liquid level in cooler will alternately rise and fall C. Cooler will continue to operate as normal for a considerable time D. Liquid level in cooler will not correspond to that in the float chamber - Answer: D. Liquid level in cooler will not correspond to that in the float chamber Ball float on high side float is punctured, how will the system be affected? A. Flood the evaporator B. High suction pressure C. Low head pressure D. Starve the evaporator - Answer: D. Starve the evaporator *refrigerant needed to condense and pass through system to the evaporator will not be able to do so* Which of the following best describes the high side float: A. Feed the evaporator when a sufficient amount of refrigerant has been condensed B. Feed the evaporator as refrigerant pressure decreases C. Feed the condenser as refrigerant is needed D. Maintain the level of condenser water in the cooling tower - Answer: A. Feed the evaporator when a sufficient amount of refrigerant has been condensed Which feature distinguishes a manual metering device from a globe valve? A. Valve seat B. Valve stem C. Needle point D. Outer diameter - Answer: C. Needle point *manual = needle* How would a partially blocked orifice effect the operation of a TEV? A. Flood the evaporator B. Starve the evaporator C. Decrease superheat D. Increase refrigerant velocity - Answer: B. Starve the evaporator *refrigerant will not be able to pass the restriction* What determines amount of refrigerant passing through an orifice plate? - Answer: Differential pressure of high and low side If an expansion valve meters too much refrigerant into a DX coil: A. Can possibly send liquid to compressor B. Evaporator temperatures will be too cold C. Reduced system capacity D. Possible motor burnout - Answer: A. Possibility of liquid in the compressor *System may not be able to convert 75% vapor/ 25% liquid into 100% liquid before reaching compressor* Reduced capillary tube length = _____________ evaporator pressure - Answer: high/increased Motor has: 120 V power source, drawing 30 amps, with resistance of 4 ohms. how many kilowatts is it consuming at full load? - Answer: Use any formula: Volts= Amp x Ohm Amps = Volt / Ohm Ohm= Volt / Amps (gives you what you need to find power) Power = Volt² / Ohm Power = Amp x Volt Power = Amps² x Ohms (Divide by 1000 to turn Watt to Kw) 3.6 Kw is answer For a single test device to qualify as multi-meter, which of the following must it test? A. Voltage, impedance, amperage B. Resistance, continuity, voltage C. Voltage, amperage, resistance D. Resistance, amperage, impedance - Answer: C. Voltage, Amperage, Resistance Power source 2 horsepower induction motor is ________________ - Answer: 3 phase 208 V, 3 phase, 4 wire power supply, which statement regarding the power across neutral line and either L1, L2, or L3 is most correct? A. Carries current all the time B. Has a potential with respect to ground of approximately zero C. Never carries current, but rather resistance D. Has a potential with respect to ground of 120 V - Answer: D. Has a potential with respect to ground of 120 V Which formula determines power consumed by a crankcase heater? A. Watts = V x I B. Watts = V x I x pf C. Watts = I x r D. Watts = v² x r - Answer: A. Watts = V x I Power source commonly used for lighting in a modern commercial building? A. 120 V 3 ø B. 440 V 3 ø C. 277 V 1 ø D. 277 V 3 ø - Answer: C. 277 V 1 ø What electrical test meter will be used to test for grounded or shorted winding? - Answer: Ohmmeter Assuming the absence of electrical fault the voltage from neutral to ground in a 460 V, 3 Phase, 4 wire system should be? A. 0v B. 105v C. 220v D. 24v - Answer: A. 0v *neutral to ground* Electrical circuits that demonstrate some sort of magnetic force will include with of the following components? A. resistor B. inductor C. transformer D. wye power source - Answer: B. Inductor *magnetic force = inductor* What device can bring 120v power source to the required 24v ? A. resistor B. rectifier C. diode D. transformer - Answer: D. transformer *Step down transformer brings voltage down* *transforms the voltage* What can store electrical energy, but unlike a battery will discharge their voltage nearly instantaneously? - Answer: Capacitors Conductor used as ground is usually __________ or _________ in color. - Answer: Green or bare Which of the following describes the relationship between current and voltage? A. voltage and current are in-phase B. Current leads the voltage C. Current lags the voltage D. Current and voltage are independent - Answer: C. Current lags the voltage *voltage is potential, current (amps) is what is used* *can only use as much energy as you are supplied* In 3 phase power how many degrees separate the individual sine-waves? A. 100º B. 150º C. 120º D. 180º - Answer: C. 120º Which of the following frequencies, expressed in Hertz, is used to deliver AC power in the United States? A. 30 hz B. 50 hz C. 120 hz D. 60 hz - Answer: D. 60 hz Mechanical equivalent of Watts? - Answer: horsepower (1hp= 746 watts) Which of the following can produce alternating power source? A. battery B. magnetic field C. generator D. rectifier - Answer: C. generator Which of the following protects electrical system and personnel from hazards associated with short circuits and overloads? A. fuse B. Circuit breakers C. variable resistors D. thermal overload - Answer: B. Circuit breakers *breaks circuit, no circuit, no power* Power consumed by solenoid valve is: A. Ohms B. Volts C. Amperes D. Watts - Answer: D. Watts *consumed/used is watts* Converts AC to DC current: A. Synchronous motor B. Generator C. Phase analyzer D. Rectifier - Answer: D. Rectifier *sole purpose* *can be done also by a generator* Which is true regarding clamp on watt meters being used to determine power in a balanced 3-phase circuit? A. Requires 3 separate watt meters with one test lead per meter B. Requires 1 watt meter, with 3 test leads per meter C. Should only be used for single phase D. Will properly read with 1 watt meter and 1 test lead per meter - Answer: A. requires 3 separate watt meters (1 for each phase) with one test lead per meter Upon opening an electrical enclosure in a residential facility, it is observed that there are 3 wires, two of which are fused. Which of the following could be an explanation for this wiring arrangement? A. The unfused wire does not need to be insulated B. Th