Refrigeration Gas-Fired Appliance Systems & Refrigeration System Operation & Refrigeration Troubleshooting & Maintenance

Question 1

Prior to commencing any maintenance activities, always adhere to

Answer 1

manufacturer’s recommended shutdown procedures
isolate the equipment from all power sources and fuel supplies

Question 2

What do you do to Conduct a thorough safety inspection of the equipment

Answer 2

checking for any signs of wear, damage, or deterioration. Verify that all safety devices are functioning properly
pressure relief valves and flame safety controls

Question 3

What do you do to ensure optimal performance and safety

Answer 3

conduct a thorough inspection and maintenance of the burner system
Clean the burner, pilot assembly, and combustion chamber to remove any buildup that could impede functionality

Question 4

Thoroughly examine the heat exchanger surfaces for what

Answer 4

signs of fouling, scaling, or corrosion that could compromise efficiency
Clean if needed and check for leaks

Question 5

Maintain condenser efficiency by cleaning the fins using

Answer 5

brush-tipped vacuum or clean, dry compressed air
Always prioritize safety by wearing protective gloves and ensuring that fins are not bent or damaged during the cleaning process.

Question 6

Carefully inspect the venting system for

Answer 6

blockages, leaks, or signs of corrosion
everything is clear
confirm that draft regulators and pressure switches are functioning

Question 7

Assess the insulation on pipes and equipment for

Answer 7

damage, wear, or deterioration. Promptly repair or replace compromised insulation to prevent unnecessary heat loss and maintain energy efficiency.

Question 8

Check refrigerant for

Answer 8

levels and refill as required, check for leaks
Ensure the expansion valve operates correctly

Question 9

Evaluate all electrical components for

Answer 9

signs of wear, corrosion, or damage, tight, clean

Question 10

Check the fans and blowers for

Answer 10

Smooth operation, Clean fan blades and motor assemblies to remove dust and debris. Lubricate the fan and motor bearings

Question 11

Inspect the equipment’s overall structural integrity for

Answer 11

signs of rust, corrosion, or physical damage. Verify that the system is securely mounted and structurally sound

Question 12

Maintain detailed records of

Answer 12

maintenance activities performed, including issues identified, corrective actions taken, and any manufacturer or technician recommendations

Question 13

Effectively troubleshooting heat input issues involves

Answer 13

systematically identifying and addressing potential causes to ensure efficient and reliable system operation

Question 14

esign the chiller/heater draught pressure at the flue flange for a negative pressure of

Answer 14

0 to -0.12 in wc (0 to -3 mmH2O).

Question 15

YORK Model YHAU-CGN/H
When the required maintenance interval has passed what happens

Answer 15

maintenance alarm is activated with the warning “Burner parts should be replaced. When the warning appears, contact your local Johnson Controls service center.

Question 16

The major inspection items are (6)

Answer 16

Checking of the action of various safety devices and adjustment
Diagnosis of the operation condition and measurement recording
Management of absorption solution and refrigerant
Management of combustion unit
Maintenance of vacuum level
Diagnosis and repair of the absorption solution pump, refrigerant pump and purge pump

Question 17

overhaul of the chiller-heater is performed

Answer 17

every 3 to 5 years

Question 18

What maintenance is provided by a separate contract

Answer 18

The cleaning of heat transfer tubes in water system is performed by a separate contract.

Question 19

The refrigerant flows through the three main circuits of an ammonia absorption refrigerator:

Answer 19

the solution circ
the condensing circ
the evaporation circ

Question 20

The operation of an absorption system is

Answer 20

thermodynamic

Question 21

ammonia
What does the generator do

Answer 21

The generator is the heat energy source that begins and maintains the operating cycle

Question 22

ammonia
What does the condenser do

Answer 22

The condenser collects the separated ammonia vapour and removes heat from the vaporized refrigerant (ammonia), causing it to condense into a liquid (now with the absence of water).

Question 23

ammonia
What does the evaporator do

Answer 23

the liquid refrigerant (ammonia) encounters a pressurized hydrogen atmosphere and evaporates once again. This heat transfer from the surrounding air into the evaporator (from evaporation) makes the tubes of the evaporator cold.

Question 24

ammonia
What does the Absorber do?

Answer 24

The absorber consists of a coil and a tank. The function of the liquid inside the absorber is to attract – and absorb – the refrigerant from the evaporator. Ammonia and hydrogen return from the inner compartment (evaporator), ammonia returns to absorber and dissolves in water. Hydrogen separates and is free to rise back to the evaporator. Ammonia/water solution (refrigerant) is then stored in the absorber tank until the generator begins the cycle again.

Question 25

Lithium bromide There are three important concepts of an absorption chiller

Answer 25

Water boils at different temperatures under different pressures Lithium Bromide is a salt Water and Lithium Bromide can be mixed together

Question 26

Lithium bromide The main components

Answer 26

condenser and the generator on top The evaporator and absorber on bottom Heat exchanger

Question 27

Lithium bromide and water mix

Answer 27

50% lithium bromide and 40% water

Question 28

If you increase the pressure, then water boils

Answer 28

much higher temperatures

Question 29

Water and lithium bromide can be mixed together how do you get them to seperate

Answer 29

Heat

Question 30

Lithium bromide weak solution

Answer 30

Lithium bromide with water

Question 31

Lithium bromide 1st step

Answer 31

water/lithium pumped from absorbed through heat exchanger to generator

Question 32

Lithium bromide What is the weak solution line

Answer 32

water/lithium pumped from absorbed through heat exchanger to generator

Question 33

Lithium bromide Step 2

Answer 33

A source of heat flows (hot water/steam or direct fired) through a pipe within the reservoir of the generator which causes the lithium bromide and water to separate.

Question 34

Lithium bromide Step 3

Answer 34

The water will evaporate as vapour and rise into the condenser section leaving the lithium bromide behind. The lithium bromide builds up and will sink to the bottom due to the weight of the molecules. This causes a concentration of lithium bromide liquid to form at the base of the generator, and this will then flow down through the heat exchanger and be sprayed over the absorber where it can mix with water molecules.

Question 35

Lithium bromide Step 4

Answer 35

the water vapour is condensing into a liquid as it comes into contact with a cooling coil in the condenser section. Water from a cooling tower passes through a sealed pipe within the condenser to remove the heat of the water vapour which causes it to condense into a liquid. This liquid water is then collected in a tray within the condenser, and this will flow through a pipe down into the evaporator

Question 36

Lithium bromide The volume flow rate of water is controlled how

Answer 36

a fixed orifice

Question 37

Lithium bromide step 5

Answer 37

The evaporator is at a very low pressure, near vacuum condition, which causes the water to flash, but will be very cold due to the rapid drop of pressure The “chilled water” line runs through the evaporator and carries all the unwanted heat of the building from the AHU’s, fan coil units, etc. This passes through a cooling coil where the cold water from the condenser is then sprayed over the surface to extract the unwanted thermal energy.

Question 38

Lithium bromide The water reduces temperature to around

Answer 38

4 degrees

Question 39

Lithium bromide The “chilled water” will enter the evaporator coil at around

Answer 39

12 degrees

Question 40

Lithium bromide Step 6

Answer 40

s the spray of the cold condenser water comes into contact with the tube of chilled water line, it will transfer its thermal energy out of the “chilled water” and into the “condenser water”. As the heat transfers through the tube wall and into the condenser water, on the outside of the tubes, the condenser water will evaporate into steam due to the low pressure of the chamber (water boils at low temperatures under low pressure). As it evaporates it carries the unwanted thermal energy away with it. The chilled water circuit has now given up its heat and by the time it leaves the evaporator it will be around 7°C (45°F) and is ready to be pumped around the building to collect more heat. Another loop will recirculate any water that missed the tubes and didn’t boil. This will be pumped back to the top of the evaporator and sprayed again until it all evaporates into steam.

Question 41

Lithium bromide The chilled water circuit has now given up its heat and by the time it leaves the evaporator it will be around

Answer 41

7 degrees

Question 42

What is Sensible Heat

Answer 42

Heat you can see, feel, sense

Question 43

Sensible heat formula

Answer 43

W X Specific heat X Delta T

Question 44

Latent heat is

Answer 44

released by a substance during a phase change

Question 45

Latent heat formula

Answer 45

Weight X specific heat

Question 46

What is Absorption refrigeration

Answer 46

the raising and lowering of temperatures and changing the state of fluids to create a cooling effect.

Question 47

An absorption system uses

Answer 47

refrigerant, adsorbent, and heat to create a cooling effect.

Question 48

Gas-fired absorption systems There are two types of systems:

Answer 48

Ammonia/water Lithium bromide/water

Question 49

Where can you find ammonia system

Answer 49

Ice arena

Question 50

Where can you find this lithium bromide

Answer 50

Hospitals

Question 51

In ammonia system what is the refrigerant and which is the absorbent

Answer 51

Ammonia is used as the refrigerant and water is used as the absorbent.

Question 52

major advantage of the ammonia-water solution is

Answer 52

water has a strong affinity for ammonia, and they are soluble with each other in wide operating conditions that occur in different refrigeration applications

Question 53

What not used in residential air conditioning applications

Answer 53

Ammonia systems

Question 54

The ammonia system uses three substances

Answer 54

ammonia, hydrogen gas, and water

Question 55

Which system can chill the air below freezing temperatures

Answer 55

Ammonia

Question 56

Ammonia strong solution

Answer 56

Water mixed with ammonia (Saturated)

Question 57

Ammonia weak solution

Answer 57

water has little to no ammonia in it (unsaturated).

Question 58

Pressure in ammonia system

Answer 58

200–230 Psig

Question 59

Which is the refrigerant and absorber in Lithium bromide

Answer 59

Water is used as the refrigerant and lithium bromide is used as the absorber

Question 60

Which refrigerant is more commonly used these days because it is safer and nontoxic

Answer 60

Lithium bromide

Question 61

Lithium bromide/water systems are called

Answer 61

absorption chillers.

Question 62

Lithium bromide/water systems strong solution

Answer 62

concentrated lithium bromide (no water), which tends to attract and absorb the water vapour (unsaturated)

Question 63

Lithium bromide/water systems weak solution

Answer 63

lithium bromide saturated with water (saturated).

Question 64

Lithium bromide/water systems can cool air down to

Answer 64

5 degrees

Question 65

The risks associated with the use of refrigerants

Answer 65

toxicity, flammability, asphyxiation, and physical hazards.

Question 66

The two main types of hazardous refrigerants used in vessel refrigeration systems are

Answer 66

ammonia and halocarbons (the most commonly recognized is Freon®).

Question 67

halocarbons (the most commonly recognized is Freon®). include

Answer 67

chloroflourocarbons (CFCs), hydroflourocarbons (HFCs), and hydrochloroflourocarbons (HCFCs), such as chlorodifluoromethane (R-22) or difluoromonochloromethane (R-134A).

Question 68

Ammonia, in liquid or gas form, can present which hazards

Answer 68

workers’ skin, eyes, nose, and lungs

Question 69

Liquid ammonia is (features)

Answer 69

clear fluid that evaporates quickly at room temperature

Question 70

gas, ammonia is (features)

Answer 70

colorless and has a strong odor that is suffocating, pungent, and penetrating.

Question 71

Is ammonia heavier or lighter than air

Answer 71

lighter

Question 72

Why is it important to take atmospheric readings at various locations with ammonia

Answer 72

Liquid releases can form aerosols that may tend to accumulate at low points.

Question 73

What can happen when you smell ammonia

Answer 73

You can lose your ability to smell it

Question 74

Exposure to ammonia at what ppm is immediately dangerous to life and health

Answer 74

300 ppm

Question 75

Personal protective equipment (PPE) should be used when there is a possibility of exposure above what ppm

Answer 75

50 ppm

Question 76

Depending on the concentration, exposure to ammonia can cause

Answer 76

can cause coughing, chest pain, breathing difficulty, bronchopneumonia, pulmonary edema, and death from bronchial spasm. chemical burns

Question 77

Ammonia vapour reacts with moisture in the air to form aqueous ammonia, which attacks

Answer 77

copper, zinc, tin, cadmium, and most of their alloys. Ammonia will also corrode many rubbers and plastics.

Question 78

Ammonia is flammable at all concentrations and explosive between

Answer 78

15% and 28% (150,000 - 280,000 ppm) in air

Question 79

Lithium bromide can present with what

Answer 79

mild irritation to workers’ skin and eyes

Question 80

As a gas, lithium bromide is (features)

Answer 80

reddish in colour, can be smelled at low concentrations (Odor Threshold = 0.00999 ppm), has an irritating odor, and can cause eyes to water uncontrollably s a highly corrosive brine and readily attacks ferrous metals such as steel.

Question 81

repeated inhalation or ingestion of inorganic bromides can cause

Answer 81

can cause rash, ringing in the ears, nausea, vomiting, diarrhea, difficulty speaking, drowsiness, twitching, visual disturbances, and coma. Ingestion of relatively large quantities of Lithium Bromide can cause kidney damage.

Question 82

Is Lithium bromide flammable

Answer 82

No

Question 83

effective program for the use and storage of ammonia must include

Answer 83

A written health and safety policy that: States the employer’s commitment to health and safety States the program’s objectives Defines the responsibilities and roles of the employer, supervisors, and workers Written safe work procedures and emergency response procedures Training for supervisors and workers Regular worksite inspections Regular health and safety meetings Incident investigations Records and statistics A joint health and safety committee or worker health and safety representative, if required