PIPE Elements 11

In a NH₃ shell-and-saving accessory to a refrigeration system
a. black iron
b. galvanized steel
c. muntz or admiralty metal
d. copper

Flapper valves in the compressor operate
a. on a pressure difference
b. on a temperature difference
c. A and B
d. none of the above

The temperature at which moisture in the air starts to condense is known as
a. relative humidity
b. dew point
c. eutectic point
d. wet-bulb temperature

Which of the following is not a refrigeration compressor seal?
a. mechanical seal
b. packing gland
c. stationary bellows
d. rotary seal

Condensing mediums must be
a. a liquid
b. a gas
c. non-corrosive
d. in the right temperature range

The atmospheric line on the indicator card of a horizontal double-acting compressor is for
a. pressure standard
b. compressor temperature
c. oil level
d. refrigerant charge

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 eith changes in the entering air wet-bulb temperature
d. decrease as the entering air wet-bulb temperature decreases

An indicator card on a horizontal compressor indicates the
a. control of water
b. tonnage capacity
c. valve efficiency
d. none of the above

Gas condenses in the anal or inner tube of a(n)
a. atmospheric condenser
b. double-pipe condenser
c. shell-and-tube condenser
d. evaporative condenser

An engine indicator diagram for a reciprocating comoressor would most likely show the
a. purity of the refrigerant returning to the compressor
b. need for additional refrigerant
c. action of the compressor valve
d. need to change compressor speed

Natural-draft condensers are most frequently found in
a. residential cooling
b. room air conditioners
c. household refrigerators
d. large industrial plants

Of the following

The capacity of an evaporative condenser is greatest on a
a. warm day
b. low-humidity day
c. cool day
d. rainy day

What is the purpose of a stuffing box seal?
a. It makes the unit start easily after lying idle overnight
b. It prevents air from entering the crankcase
c. It lubricates from enterinf the crankcase
d. it prevents refrigerant leaks from the crankcase

The capacity of an evaporative condenser depends on
a. fan horsepower
b. entering air wet-bulb temperature
c. the temperature of the entering air
d. the amount of heat leavinf air is capable of absorbing

Packing in the stuffing box is
a. made of metal with oil passing through
b. made of metal with oil passing through

The following does not increase the capacity of a water-cooled condenser
a. increasing the water flow
b. reducing the water temperature
c. decreasing the ambient temperature
d. none of the above

As capacity decreases in a reciprocating compressor
a. suction pressure increases
b. suction pressure decreases
c. volumetric efficiency increases
d. head pressure decreases

open shell-and-tube condensers are mainly used with
a. a cooling tower of spray pond
b. dirty water
c. chemically treated water
d. hard water

A superheated refrigerant

If shell-and-tube condenser were removed and an evaporative condenser were installed

The main reason for insulating the suction piping of a compression-type refrigerating system is to
a. absorb moisture condensation
b. prevent loss of refrigerating capacity
c. reduce compressor vibration
d. increase circulation of the lubricating oil

A cooling tower
a. is always used if water is scarce
b. is an accessory to a condenser
c. helps the operator maintain pressures
d. must be in a location where the prevailing wind blows

The high-pressure relief valve is usually piped to
a. the low-pressure side and the atmosphere
b. the mixer only
c. atmosphere and a water tank
d. fire department box and water

Of the many ways to control condensing pressure

Gauge glass connection on a horizontal liquid receiver should be
a. top and bottom with ball check valve
b. top and slightly off bottom with ball check valve and tight packing
c. top and slightly off bottom with ball check valve and free packing
d. slightly off bottom with ball check valves and tight packing

If a system operated with suction stop valve closed and the discharge stop valve open

The pressure connection of an automatic water-regulating valve is connected to
a. discharge pressure
b. city water pressure
c. suction pressure
d. the suction service valve

At a given temperature

Which of the following is not on the high side?
a. oil trap
b. liquid seal
c. scale trap
d. king valve

The capacity of a water-cooled condenser us least affected by
a. the amount of water circulated
b. the temperature of the water
c. the amount of gas circulated
d. the ambient temperature

A side-outlet drier is generally mounted
a. just after the expansion valve
b. between the evaporator and the compressor
c. liquid line

What effect would a refrigeration overcharge on the system?
a. head pressure would increase
b. head pressure would decrease
c. suction pressure would decrease
d. discharge pressure would decrease

A drier is generally installed with other essential equipment. The recommended location is on the
a. high-pressure line between the condenser and the receiver
b. suction line between the evaporator and the compressor
c. discharge line between the compressor and the condenser
d. liquid line between the receiver and the expansion valve

The leaving water temperature of an induced-draft cooling tower that is operating efficiently is
a. 10⁰F higher than entering water temperature
b. some temperature between dry and wet bulb temperature
c. at the dew-point temperature
d. at the dry-bulb temperature

What driers are used in R-12 systems?
a. calcium chloride
b. activated alumina
c. sodium chloride
d. soda lime

The wet-bulb reading is higher than the dry-bulb reading when
a. relative humidity is 100% and temperature is above 32⁰F
b. relative humidity is 100% and temperature is below 32⁰F
c. relative humidity is above 200%
d. This can never happen

Of the following

An evaporative condenser is constructed so that
a. refrigeration is sprayed over tubes
b. refrigeration is in the tubes and air is over the tubes
c. refrigeration is in the tubes while air and water are over the tubes
d. non-condensable are easily removed

The purpose of using activated alumina on the high side of a Freon refrigerating system is to
a. regenerate refrigerant
b. remove non-condensable
c. dry the refrigerant
d. remove excess oil

Which statement concerning the evaporative condenser is correct?
a. an evaporative condenser and spray pond most nearly alike
b. evaporative condensers depend on recirculation of bay water or ocean water
c. a closed induced-draft evaporative condenser utilizes stack effect
d. evaporative condensers depend on evaporation effect for economical operation

Which of the following is a drying agent?
a. sulfur dioxide
b. ethyl chloride
c. hydrocarbons
d. calcium sulfate

cooling tower shoukd be maintained at a pH near
a. 4
b. 6
c. 8
d. 10

An air conditioning system with clogged filters will have one of the following conditions
a. low suction-pressure to the compressor
b. high head pressure to the compressor
c. high-suction pressure to the compressor
d. increased suction pressure

One effect of non-condensable gas in a system is
a. high suction pressure
b. low suction pressure
c. high condenser pressure
d. low condenser pressure

Which dessicant changes chemically or physically in a refrigeration system?
a. activated lumina
b. silica gel
c. calcium chloride
d. bauxite

Which would not cause high discharge pressure?
a. an undersized condenser
b. insufficient condenser water
c. refrigerant undercharge
d. none of the above

If silica gel contained water before being installed in the system

In a vertical open shell-and-tube condenser

Liquid slugging is
a. liquid in compressor clearance space
b. excessive liquid refrigerant in the receiver
c. the pounding of liquid refrigerant in the suction line at a point of refrigerant restriction
d. liquid in the condenser causing excessive noise

In a refrigeration system using a reciprocating compressor and a water-cooled condenser cooling tower

In a single-acting compressor
a. piston speed can be automatically controlled
b. refrigerant gas is compressed alternately on one side

An evaporative condenser operation most efficiently when
a. the dry-bulb temperature of the air is high
b. the wet-bulb temperature of the air is low
c. wet and dry-bulb temperatures are high
d. the wet-bulb temperature is high

A refrigerating compressor is driven by a squirrel-cage induction motor. The operator can run this compressor at
a. one speed
b. two speeds
c. three speeds
d. four speeds

The horizontal shell-and-tube condenser is more efficient than the vertical shell-and-tube condenser because
a. it is mounted in a horizontal position
b. it is easier to clean
c. water passes through it more than once
d. it take advantage of more air cooling

In a well-lubricated refrigeration compressor

Why have a receiver in a refrigeration system?
a. it's necessart component
b. it aids an expansion device
c. it's needed on the lowside of the system
d. it's used as a storage tank

On a compression-tyoe refrigeration plant

In the condenser
a. heat is absorbed
b. heat is pressurized
c. heat is given up
d. all of the above

If the compressor on a reciprocation system is V-belt driven and the belts are installed too tightly

A compressor seal is a means of closing off the
a. suction from the discharge side
b. condenser from the receiver leakage
c. crankcase

The suction line back to the compressor is insulated to
a. prevent condensation on the line
b. help efficiency
c. provide motor cooling
d. all of the above

As suction pressure in a reciprocating compressor increases and the horsepower decreases

To lubricate a centrifugal compressor

When head pressure decreases in an ammonia compressor

If the piston is at the top dead center of the stroke

When suction pressure decreases

A reed valve normally has
a. four springs
b. two springs
c. no springs
d. The number of springs is determ8ned by the vakve size

The most accurate of the following statements about compression ratio of a reciprocating compressor is
a. it remains constant under all compressor operating conditions
b. it varies according to the conditions under which the compressor operates
c. it is the ratio of the suction pressure gauge to the discharge pressure gauge
d. it equals the saturated discharge temperature divided by the saturated suction temperarure

An atmospheric line on an indicator card from the head of a double-acting

Compression ratio in a refrigeration compressor
a. is the ratio of absolute suction pressure to absolute discharge pressure
b. is increasing due to advances in gasoline octane
c. is the ratio of absolute discharge pressure to absolute suction pressure
d. is constant with each compressor

The engine indicator diagram would most likely indicate
a. purity of refrigerant coming back to compressor
b. need for more refrigerant
c. condition of the valves
d. the compressor's need to change speed

A compressor capacity reduction device always
a. reduces compressor capacity by using a hot-gas bypass
b. reduces compressor capacity by reducing compressor speed
c. reduces comprrssor capacity by reducing horsepower proportionately
d. reduces compressor capacity as the refrigerant load dictates

All refrigeration compressor valves are
a. opened and closed by camshaft
b. opened and closed by inherent spring tension
c. opened and closed by external springs
d. opened and closed by pressure difference

On a wet-compressiin system

A reciprocating compressor
a. never has a provision for an indicator card
b. operation can be checked with an indicator card
c. operates an indicator card by a cord running from the shaft
d. moves the indicator card from a telescopic oiler

Which compressor gives the least side thrust when operating?
a. hotizontal open
b. radial
c. vertical
d. Y compressor

The opening and closing of suction and discharge valves on a reciprocating compressor is shown by
a. a bailey meter
b. an indicator card
c. a mercury manometer
d. a discharge and suction gauges

What causes oil to foam in the compressor crankcase?
a. pressure change
b. load change
c. temperature change
d. all of the above

Clearance volume
a. affects compressor capacity
b. does not affect compressor capacity
c. varies depending on compressor speed
d. is the same on all compressors

Foaming in the compressor crankcase is caused by
a. refrigerant overcharge
b. rise in discharge pressure
c. refrigerant undercharge
d. sudden drop in crankcase temperature

The most accurate statement about an R-12 reciprocating compressors that has been shut down is that oil is
a. pumped into a service valve in the high pressure liquid line
b. pumped into a service valve on the compressor crankcase
c. sucked into suction service valve on the compressor
d. pumped into the compressor discharge service valve

Which of the following is not a design factor affecting compressor capacity?
a. compressor speed
b. clearance space
c. pistin displacement
d. suction drop and discharge valve design

As the horsepower of a compressor decreases
a. head pressure increases
b. compressor capacity decreases
c. compressor ratio increases
d. volumetric efficiency increases

If refrigeration is to be changed to another type in an R-12 compressor system

When throttling the discharge on a centrifugal brine pump
a. pressure goes up and horsepower goes down
b. pressure goes down and horsepower goes up
c. pressure and horsepower go up
d. pressure and horsepower go down

If the cut-in and cut-out settings are too close on an R-12 compressor
a. the compressor will not cycle off long enough to allow oil to return to the crankcase
b. the compressor will not start
c. the compressor will run continuously
d. the compressor will cut-out on high head pressure

Ehat would happen if you ran a reciprocating compressor with the suction vakve closed and the discharge valve open?
a. The plant capacity would increase
b. The compressor head would blow off
c. Non-condensable gases would enter the compressor
d. Head pressure would rise

A reciprocating compressor is operating with a matched set of five belts. One of the belts is worn out. What should you do?
a. replace the worn belt with a new one
b. replace all five belts
c. remove the worn belt and operate on four belts
d. replace the worn belt and add two belts

The item that should be engaged first when starting a centrifugal water chiler system is the
a. centrifugal compressor
b. condenser water pump
c. cooling tower fan(s)
d. chilled water pump

Ehich of the following would not help determine compressor displacement?
a. length of piston
b. revolutions per minute
c. diameter of piston
d. number of cylinders

A mechanical shaft seal is necessary in a
a. hermetic reciprocating compressor
b. semi-hermetic compressor
c. open-type compressor
d. hermetic rotary compressor

A compressor may lose oil if
a. there is air in the system
b. the velocity of refrigerant in the risers is too low
c. there are medium pressure drops in the evaporator
d. there are small load variations in the system

Assume an ammonia wet-compression system is replaced by an ammonia dry compression system in a particular process plant. If the capacity remains the same

A reciprocating refrigeration compressor is controlled by the temperature of water leaving the water chiller. If the thermostat used for compressor control result would be
a. inadequate time for oil to return to the compressor
b. stop on low-pressure cut-out
c. stip on high-pressure cut-out
d. a ver long operating cycle

The compressor uses a set of valves to comoress refrigerant gas. These valves are
a. read valves
b. flapper valves
c. A and B
d. rex and hex vakves

During the re-expansion portion 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

The compressor produces heat in the gas it discharges. This work energy is known as
a. heat of convection
b. heat of conduction
c. A and B
d. heat of compression

A liquid-line cooler is sometimes installed in a Freon compression system. The net result is generally
a. a decrease in liquid-line friction
b. a decrease in suction-gas temperature
c. an increase in compressor displacement
d. an increase in refrigeration effect per pound pumped