Block 2 - Gas-Fired Refrigeration Equipment Self Assessment Flashcards
Which formula calculates the energy required to absorb or liberate heat without a phase change?
Sensible heat formula
What is the odor threshold of ammonia?
2 ppm
What is latent heat associated with?
Phase changes in a substance
Why is a formal risk assessment important for ammonia exposure control?
To identify affected workers and determine the extent of exposure
What is the primary advantage of lithium bromide systems?
They are nontoxic and safer to use.
What is the typical cooling limit of lithium bromide systems?
Around 41°F (5°C)
What should exposure control plans include?
Procedures for reducing exposure risks
What defines a “strong solution” in a lithium bromide/water system?
High lithium bromide concentration with no water
At what pressure range does the ammonia system typically operate?
200-230 Psig
Which substance in a lithium bromide system is highly corrosive to ferrous metals?
Lithium bromide
What substance is used as the absorbent in an ammonia/water system?
Water
What is the primary safety advantage of lithium bromide systems?
Non-flammable and nonreactive under most circumstances
Which refrigerant is associated with risks such as toxicity, flammability, and asphyxiation?
Ammonia
What is a potential hazard of ammonia exposure to workers?
Severe eye irritation and burns
What does an absorption refrigeration system use to create a cooling effect?
Heat, refrigerant, and adsorbent
Why is ammonia considered flammable and explosive?
It has an explosive range between 15% and 28% in air.
In which type of facility is an ammonia/water absorption system commonly found?
Ice arenas
What is required in an effective program for ammonia use and storage?
1) Regular inspections and a WHMIS program
2) Written safe work procedures
3) Emergency response plans and training
At what concentration is ammonia considered immediately dangerous to life and health?
300 ppm
What type of heat causes a change in temperature without a change in state?
Sensible heat
What is the approximate temperature of the chilled water as it exits the evaporator?
7°C (45°F)
Which substance acts as the absorber in a lithium bromide/water system?
Lithium bromide
Which energy sources can be used for the generator in an absorption system?
Natural gas, propane, or steam
What is the purpose of cooling tower water in a lithium bromide system?
Condense vapor particles and remove heat from the system
What creates the vacuum condition in the absorber chamber of a lithium bromide/water system?
Strong attraction between water vapor and lithium bromide
What causes the boiling point of water to change in an absorption system?
Absorption by lithium bromide
Which of the following best describes the weak solution in a lithium bromide system?
Variations in system pressure
At what pressure does water boil at approximately 4.5°C in a lithium bromide absorption system?
0.84 kPa
What does the term “flash” mean in the context of the evaporator?
Sudden evaporation of water at low pressure
What is the term for lithium bromide saturated with water?
Weak solution
What is the role of the heat exchanger in a lithium bromide system?
Improve system efficiency by preheating the solution
What is the primary purpose of the evaporator in both ammonia and lithium bromide systems?
Remove heat from the refrigerated space
What is the primary refrigerant used in an ammonia/water absorption system?
Ammonia
What is the primary function of the generator in an ammonia absorption refrigerator?
Separate ammonia from the water solution
Which component removes heat from the ammonia vapor, causing it to condense into a liquid?
Condenser
In the evaporator, what causes the tubes to become cold?
Evaporation of ammonia in a hydrogen atmosphere
What is the role of the absorber in an ammonia/water absorption system?
Attract and absorb ammonia from the evaporator
What happens to water vapor in the condenser of a lithium bromide system?
It condenses into liquid
Why is lithium bromide used in absorption chillers?
It can easily separate from water when heated
What happens to lithium bromide in the generator?
It remains as a concentrated liquid at the base
Why does LG recommend a yearly maintenance contract?
To ensure stable operation through scheduled upkeep
What is the recommended solution for fouling on heat exchanger surfaces?
Perform a thorough cleaning
What should be done if refrigerant levels are low?
Refill and check for leaks
How often should safety devices like pressure relief valves be checked?
Annually
What is the primary purpose of annual maintenance on industrial direct-fired refrigeration chiller equipment?
Detect potential issues early
What is the key indicator of improper combustion during air-fuel ratio checks?
Excessive CO levels
Which of the following requires a separate maintenance contract?
Cleaning heat transfer tubes
According to CARRIER, what should be done if multiple systems share the same exhaust stack?
Prevent backflow of exhaust gases
What is the first step in the maintenance shutdown procedure?
Disconnect power sources
What tool is recommended for cleaning condenser fins?
Brush-tipped vacuum
How often should the burner main body components be checked?
Annually
How frequently should major inspections for safety devices and adjustments be performed according to LG?
Yearly
Why is it important to calibrate temperature and pressure sensors?
To maintain accurate system control
Which maintenance task prevents heat loss and ensures energy efficiency?
Repairing damaged insulation
What is the first step in troubleshooting a heat input issue?
Verify fuel supply
What issue does vent blockage most commonly cause?
Incomplete combustion
Which safety device ensures proper draft in a venting system?
Draft regulator
Which component must be inspected for wear, corrosion, or damage during combustion system maintenance?
Burner assembly
What is the purpose of a condensate drain in a venting system?
Handle moisture from high-efficiency systems
