Modern Refrigeration Chapter 54 WB

If an EEV's controller has a temperature sensor at the evaporator inlet and another temperature sensor at the evaporator outlet, it will be able to calculate and monitor _______.

Evaporator superheat

If a technician inspecting a multiple-evaporator refrigeration system compared two pressure measurements (one taken from an evaporator with an EPR and another taken from evaporator without an EPR), most likely the __________.

Evaporator with a EPR would have a higher pressure measurement

If a technician inspecting a multiple-evaporator refrigeration system noticed that an evaporator with an EPR was operating at a higher temperature than an evaporator without an EPR, it would appear that ________.

Everything seems to be operating properly

Erratic refrigeration and constant oil slugging or pumping most likely indicates ______ in the system.

Excess oil

When an open-drive reciprocating compressors is producing a sharp clicking noise during operation, the problem is most likely _______.

Faulty inlet and discharge valves

A saf installation includes having a motor's __________ grounded.

Frame

An open-drive reciprocating compressor should be repaired or replaced if when it is isolated from the rest of the system, it cannot, ________.

Hold and maintain pressures produced, produce sufficient high pressure, produce sufficient vacuum.

On a compressor motor that is in good working order, the normal winding resistance reading are usually ________.

In the single or low double digits.

When performing preliminary testing for grounded (shorted-to-ground) windings in a motor, a winding in good condition should show a measurement of ________.

Infinity

High head pressure in an air-cooled condenser may be caused by ________.

Noncondensables in the system

Concerning any refrigeration system using a hermetic compressor, its ______ should be tested for acidity.

Oil

When servicing a single compressor, do not start the unit without having a fully functioning _______ in the circuit.

Overload cut-out device

A quick way of locating possible unintentional pressure drops along a liquid line is by _________.

Performing a temperature survey

Before checking whether the proper voltage is available at a specific component, be sure to _______.

Set your meter to the proper setting.

An open-drive reciprocating compressor's intake and exhaust valves can be checked for leaks by isolating the compressors from the system and connecting a gauge manifold. A leaking exhaust valve on the compressor is evident if the high-pressure gauge measurement _______ after being pressurized.

Slowly drops lower

An open-drive reciprocating compressor's intake and exhaust valves can be checked for leaks by isolating the compressors from the system and connecting a gauge manifold. A leaking intake valve on the compressor is evident if the compound gauge measurement _______ after a vacuum is pulled.

Slowly rises higher

The term "condenser capacity" generally refers to ____________.

The amount of heat a condenser can reject.

How does ambient temperature effect the amount of heat an air-cooled condenser can reject?

The higher the ambient temperature, the less heat it can reject.

How does surface area affect the amount of heat a condenser can reject?

The more the surface area, the more heat it can reject.

Sweating or frosting on the suction line beyond a TXV's sensing bulb likely indicates _______.

Too much refrigerant flow

True or False. Controllers used with EEVs usually have a self-diagnostic function with codes specific to each manufacturer.

True

True or False. Most commercial air-cooled condensers can be cleaned by a high-pressure jet of air, high-pressure water with detergents, mechanical scrubbing, or a vacuum cleaner.

True

True or False. Most commercial compressors have an oil sump and oil drain to permit oil sampling and removal.

True

True or False. One indication of excess water flow is a continuous flow of water during the Off Cycle in a water-cooled condenser.

True

A motor that is exhibiting excessive endplay can be remedied using _________.

Washers

An external motor's sheave should be checked using a(n) _______.

Wear gauge

A motor winding insulation test is best done using a(n) ________.

Megohmmeter

The placement of a TXV's bulb is based on the ________.

Size of the suction line tubing

Most EEVs use a _______ to move a position the valve's plunger.

Stepper motor

The primary purpose of a liquid line in a commercial refrigeration system is to deliver a steady stream of high-pressure _______.

Subcooled liquid refrigerant

To avoid overlooking details, a commercial refrigeration system should be inspected in a __________ manner.

Systematic

A noisy external motor should prompt a technician to check pulley bearing __________ to determine whether the bearings should be lubricated or replaced.

Temperature

A very noisy condition in which a single, distinct thump (Tap) is heard in the pipes just as a valve closes describes the term ______.

water hammer

Water flow through a water-cooled condenser should be adjusted so the temperature rise of the water does not exceed a ________ rise.

15˚F

A starving evaporator would likely be caused by the following problems.

A clogged inlet screen in a TXV, frozen moisture in the TXV's valve body, or a loss of refrigerant from a TXV's sensing bulb.

A gauge manifold is connected to an open-drive compressor that is isolated from the rest of the system. A technician turns the compressor's crankshaft a few times to produce vacuum in the crankcase and high pressure in the discharge. A crankshaft seal leak would then be indicated by ________.

A gradual rise on the compound gauge

The materials sulfate, lime, and iron cling to the inner walls of a water-cooled condenser because of ________.

An attraction of opposite charges

Generally, the liquid line in a commercial refrigeration system should _______.

Be the same size as the liquid receiver service valve connection

The most common trouble of the shaded-pole motors used to drive fans is worn _______.

Bearings

The following checks should be done on many open-drive compressors.

Belt alignment, belt condition and tightness, coupling connection and condition.

The primary danger of acidity to a hermetic compressors is ________.

Breakdown of winding insulation

A major concern for electrical wiring for refrigeration systems is that the wires must be large enough to in order to ________.

Carry the necessary amount of current

When using a clamp-on ammeter to check the current draw on a given electrical load, be sure to ________.

Clamp around only one of the load's wires

Evaporator pressure regulators (EPRs) are known by these other names.

Constant pressure valve, Open on rise of inlet pressure (ORI) valve, Two-temperature valve.

Commercial compressors often permit sampling and removal of oil through the use of an oil sump or ________.

Drain

A worn piston or cylinder in an open-drive reciprocating compressor is indicated by a _________.

Dull clicking

If a technician took measurements that indicated that an evaporator was maintaining a cooler than normal temperature, the reason could be that the evaporator's __________.

EPR is leaking.

If a technician took measurements that indicated that an evaporator was rather warmer than, the reason could be that the evaporator's _________.

EPR is stuck shut