In an ammonia absorption system, the strong liquor is composed of which of the following?
Ammonia and salt
Ammonia and brine
Water and ammonia
None of the above
All of the above
At a pressure of around 240 kpa, ammonia will boil off at a temperature of about___, in the evaporator by absorbing heat from the medium to be cooled?
-89 degrees
-65 degrees
-15 degrees
10 degrees
An intercooler used in a compression refrigeration system serves to do which of the following?
Reduce the vapor temperature
Increase vapor density
Permits a decrease in the power consumption of the high pressure compressor
Which of the following is incorporated between the discharge and suction of two separate single stage compressors in order to remove some of the heat added in the low pressure stage?
Intercooler
Aftercooler
Evaporator
Condenser
In order to handle large volumes of vapor coming from the evaporator, multi- stage plants may employ which of the following for the first of low pressure stage?
Vaporization Compressor
Booster compressor
Variable speed compressor
Which of the following maintains a constant level of liquid refrigerant in the evaporator?
Expansion valve
Liquid receiver
Evaporator float valve
The different types of refrigeration plants are which of the following?
Constant Expansion system
Direct system
Indirect system
B and C
In the duplex compressor system, the condenser for the first stage is the evaporator for the second stage?
Which of the following are different types of construction for an evaporator?
Bare tube
Finned Tube
Plate surface
1 and 2
Which of the following are major components of the high pressure ammonia refrigeration system?
Compressor
Liquid Receiver
Some of the most common refrigerants used today are which of the following?
Refrigerant R- 12
Refrigerant R- 22
Refrigerant R- 134a
Ammonia
Which of the following properties should fluids, used as a refrigerant, possess?
Non flammable
Non corrosive
Non toxic
Operate under low pressure (low boiling point)
When starting up a compressor and a leak has been found, which of the following steps would be the corrective action?
Shut down the compressor until the leak is repaired
Continue with the start up and ignore the leak
If possible, bypass the line which is leaking
What would be the final step in the start up of a compressor?
Check the gearbox oil level
Slowly load up the compressor
Close the breaker for the compressor motor
Check for leaks and unusual noises
Which of the following steps comes first when starting up a compressor that was taken down for maintenance?
Start the compressor
Check oil levels
Ensure no one is working on the compressor
Turn on the cooling water for the compressor cylinders
Open the suction and discharge valves
Which of the following should never be placed in the line between compressor and receiver, unless a safety valve is used?
Drain valve
Pressure regulator
Orifice plate
Shut off valve
Air receivers serve to perform which of the following functions?
Act as a reservoir in the compressed air system
Acts to dampen pulsations in the discharge pressure
Allows moisture, dust, and oil to settle out from the air
The standard desiccant used in an air dryer system is which of the following?
Activated alumina
Silica gel
Potassium oxide
Which of the following are components of an air dryer system?
Prefilters
Dryer tanks or towers
Afterfilters
Which of the following functions does the dry air receiver serve to do?
Stabilizes the system pressure as it acts as a demand reservoir
Helps avoid overloading the air purification system with surges in air demand
Dampens out the dew point and temperature spikes
Which of the following functions does the wet air receiver serve to do?
Stabilize flow though the air driers on system load changes
Additional moisture separation
Provides storage capacity to prevent rapid compressor cycling
none of the above
What is the main purpose of an intercooler?
To remove any entrained moisture
To reduce the volume of the air
To maintain the outlet temperature
Which of the following are some of the reasons for using intercoolers and aftercoolers to cool down the air?
To condense out water vapor and drain from the system
To remove all oil vapors that will have detrimental effects on the system
Decrease the amount of power to compress the air
To make cylinder lubrication more effective
Some common methods used to reduce “surging” would be?
Throttling the inlet valve
Reducing the compressor speed
Venting of the discharge line to atmosphere, or to the suction line
