Refrigeration System Operation Flashcards
Double suction riser are used in refrigeration system when
large fluctuations in system capacity will occur
Suction risers are typically reduced by one size over that of the main suction run
to increase refrigerant velocity to aid in proper oil return
When soldering a copper pipe connection which of the following processes allow for alloy to be draw into the space between copper pipe and the fitting connection?
capillary action
Before proceeding to make any braze connection in a refrigeration system all of the internal piping should be purged of atmosphere with
CO² or nitrogen
The liquid receiver is located between the?
condenser and the expansion device
Which device is used in a refrigeration system to protect the compressor from liquid slugs?
suction accumulator
Which device is used to stop the flow of liquid or vapor in a refrigeration system?
solenoid valve
Why is it important to know the direction that a scroll compressor is rotating?
it will only pump refrigeration in one direction of rotation
An electric motor that has a voltage rating of 120 volts will have an upper and lower allowable voltage limit of
108 to 132 V
The flapper valve design is less efficient than the discus valve design because
the cylinder has more clearance volume than the discus
Liquid refrigerant entering the compressor is potentially more damaging for this type of compressor over the others listed
reciprocating
Discus, ring, and flapper valves are not used on
screw compressors & scroll compressors
The main function of a condenser in a refrigeration system is?
reject the heat that is absorbed in the evaporator
The shell and tube condenser is a type of
water cooled condenser
One of the main disadvantages of a water-cooled condenser is that mineral deposits can build up acting as a/an
insulator
A flow regulating valve could be used on this type of condenser
shell and tube & tube in tube
On a water cooled condenser the water leaving the condenser is normally ______ lower than the condensing temperature of the unit
10º F
On a standard efficiency air-cooled condenser the ambient air entering the condenser will be approximately ________ lower than the condensing
temperature if the unit is under normal load and properly charged
30º F
A head pressure control system would be used on this type of application
unit located in a colder climate operating all year
What type of expansion valve regulates its flow based from suction line superheat?
TXV
Systems where the pressure drop across the evaporator is excessive would typically use a/an.
externally equalized TXV
On a system equipped with a TXV, when the load on an evaporator decreases.
the TXV decreases the flow of refrigerant
When referring to a power head on an expansion device the bulb is
normally charged with a fluid similar to that of the system refrigerant
By subtracting the low side evaporator outlet temperature from the low side saturation temperature the technician would be calculating?
evaporator superheat
On a typically evaporator employing a TXV the liquid refrigerant should be completely boiled to a vapor?
near the evaporator outlet
What type of TXV would be best for an application that was exposed to fluctuating ambient temperatures?
balanced port TXVs
Pressure-limiting TXV’s are generally applied on systems when
it is necessary to shut off the refrigerant flow to the evaporator when the suction pressure reaches a predetermined pressure
Which of the following is not true regarding the evaporator in a refrigeration system?
it rejects heat from the conditioned space
Heat that is added to the refrigerant stream after the 100% saturated vapor point is called?
superheat
Multiple refrigerant circuits are preferred on evaporators that are?
large or long
In a system where the evaporator temperature operators above 32º F the technician needs to be concerned with?
none of the above
The fin spacing per inch on a medium-temperature evaporator is
closer together than on low-temperature evaporator
A refrigeration system that utilizes two or three stages of low temperature refrigeration
is called a cascade refrigeration system
When leak testing a refrigeration system using a high pressure nitrogen tank the technician should always
use a pressure regulator and safety relief value at the nitrogen tank
The maximum pressure that can be applied to a refrigeration system when pressure testing is
determined by the systems rated nameplate test pressures
The safest way to charge refrigerant into a system that is running is with
vapor into the low side
When heating a refrigerant cylinder the technician should never use
any type of open flame
Refrigeration systems must be fully evacuated before charging with refrigerant
to remove air and moisture from the system
A vacuum pump will lose its ability to draw a deep vacuum over time because
the oil becomes full of moisture and acids which will decrease the capability of the vacuum pump
A refrigerant service valve must be placed in the
mid position in order for the technician to access the system
When using a micron gauge to measure vacuum the system should be evacuated to a level of _____ to ensure that non condensables and moisture have been adequately removed
500 microns
