Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
66 Cards in this Set
- Front
- Back
|
Minimum wall thickness for refrigeration pipe insulation is based upon which? |
The colder the SST, the thicker the wall insulation |
|
|
If a system operates with low compressor amperage, high suction pressure and low head pressure... |
Defective compressor suction or discharge valvels) |
|
|
Every hot gas defrost system is susceptible to thermal shock. |
True |
|
|
When performing maintenance on a compressor, which of the following is the most important if limited on time? |
Test the oil failure controller |
|
|
What is the most common defrost? |
Time initiated, temperature terminated |
|
|
What is the most commonly used defrost type used in a blast freezer? |
any type of hot gas defrost method |
|
|
What type of defrost would not work on a blast freezer |
Natural defrost |
|
|
What is the most commonly used defrost type used in a blast freezer? |
Hot gas |
|
|
When a contactor coil reads "OL” it means the coil is open and it will not energize unless excess voltage is used. True or false? |
False |
|
|
Which of the following diagram requires the lowest breaker rating? |
Solenoid drop |
|
|
Which unloader works by blocking the suction gas from entering the cylinders? |
Suction cut-off |
|
|
This unloader works by limiting the amount of suction gas being trapped as it moves from the suction to the discharge. |
Slide Valve |
|
|
Which of the following is the most reliable defrost initiation? |
Time initiated |
|
|
This type of hot gas defrost loses most of its heat the longer the defrost last. |
3 pipe conventional flow |
|
|
This type of defrost uses a 4-port reversing valve. |
Reversing cycle |
|
|
"I cause a pressure difference between the discharge gas flowing through a defrosting evap and the liquid line header" |
Defrost differential regulator |
|
|
With a system low on gas, which of the following is accurate? |
A SST low, SDT low, SH high, SC low/gone |
|
|
A system with a plugging cap-tube, which of the following is accurate? |
SST low, SDT slightly lower, SH high, SC higher |
|
|
High SST with low compressor amperage |
Inefficient compressor |
|
|
Low SST, Low SDT, High SH, Normalish SC |
Defective TXV |
|
|
High SST, High SDT, SH normal, SC normal |
Dirty condenser TXV system |
|
|
All ice machine uses water as part of its harvest process. |
False |
|
|
When cleaning an ice machine, what should be done with the ice already in the bin? |
Must be removed before any chemical is used |
|
|
A flaker ice machine has a define freeze cycle and a define harvest cycle |
False |
|
|
Industrial ice is usually called |
Block ice |
|
|
A court house without jail cells falls under which classification? |
Public assembly |
|
|
Public assembly location mostly allows which type of refrigerant? |
A1 |
|
|
When selecting a liquid line solenoid valve, the B-52 says, |
The components must be of equal pressure holding capacity as the receiver |
|
|
NH3 falls under the ASHREA 34 classification... |
B2 |
|
|
Ammonia, R717, is by far the best refrigerant known to man bar none. |
False (water) |
|
|
Which of the following ammonia compressor requires oil separators? |
All of them |
|
|
Which of the following ammonia compressor require cooling of the head? |
Only reciprocating compressors |
|
|
What is the maximum suction line velocity when there is a riser present? |
3000 fpm |
|
|
What is the maximum suction line velocity when there is no riser? |
3000 fpm |
|
|
What is the minimum velocity on a liquid line? |
No minimum |
|
|
What is the maximum velocity on a liquid line? |
300 fpm |
|
|
What is the maximum velocity on a liquid line? |
300 fpm |
|
|
The condensate line is.. |
Typically one size larger than the liquid line |
|
|
On a refrigeration system (not ammonia), the pipes are slopped... 油 |
In the direction of flow |
|
|
What is the maximum temperature penalty allowed on a suction line? |
2F |
|
|
Double risers are mostly used exclusively with system that have... |
Unloaders |
|
|
In regards to components balancing, evaporators have a capacity that is linear. The larger the TD, the... |
Higher the evaporator capacity |
|
|
In regards to components balancing, the compressor capacity... |
Increases as the SST increases |
|
|
In coolers, bacteria will grow when the TD is... |
Below 8F |
|
|
Heat load that passes through a material. |
Transmission load |
|
|
Heat load that enters through an opening, |
Infiltration load |
|
|
When freezing a product, which step is usually the largest load on the syster? |
Latent Change |
|
|
Heat load that includes people heat load. |
Misc |
|
|
Which unloader type works by moving a disk to not allow any gas to be compressed by lor more cylinder? |
Suction disk lift |
|
|
This component is used to initiate defrosts whenever a pre-determined time is reached. |
Time Clock |
|
|
This type of defrost initiation is recognized as the most energy efficient. |
On-demand initiation |
|
|
Another acronym for EPR's is... |
ORI |
|
|
Which of the following components is used to replace a CRO? |
TXV with pressure limiting |
|
|
Which of the following is recognized as the simplest head pressure control for small AC systems? |
Fan cycling |
|
|
An accumulator is sized according to? |
System capacity in tons |
|
|
Which diagram type requires an actual call for cooling for the compressor to be allowed to start? |
Solenoid drop |
|
|
The B-52 specifies that "If a leak over 22lbs is found, it must be reported to environment Canada" |
False, that is in your refrigeration handling manual |
|
|
On a wiring diagram, if there is no ground shown, it is safe to assume it was just missed by the engineering department. |
False |
|
|
Before installing gauges, if the amperage shows lower than normal, what can be assumed of the suction pressure? |
Lower than normal |
|
|
Which of the following type of diagram may be susceptible to short cycling conditions? |
Pump down |
|
|
What is the most common reason for frost build up on an evaporator coil? |
Dirty Evap |
|
|
How does suction cut off work? |
Discharge gas is used to push a spring closed that would otherwise be fully extended causing a valve to seat on a port located on the suction inlet port. This would block all suction gas. Literally cuts off suction. |
|
|
How does a hydraulic unloader work? |
A rod keeps the suction reed pressed open. Once oil pressure is created then the rod will moved off the suction reed and the cylinder will go online.
Unloaded cylinders will start unloaded and will come online after a period of time. |
|
|
Which type of diagram will not allow the system to pump down at any time? |
Solenoid drop The temperature control is in series with the compressor so if the temperature control is satisfied then the compressor will de-energize. |
|
|
Which system has the highest breaker rating? |
Pump down.
This system will be pumping down and have an electric heater running at the same time.
Solenoid drop has the smallest breaker rating because it will turn everything off. |
|
|
Water assisted defrost on an ice-machine uses what temperature of water? Minimum!! |
45F 20-80 PSI recommended |
