WAEC Refrigeration And Air-Conditioning Syllabus

Safety and first aid in the workshop

Workshop rules and regulations

Safety devices/equipment – helmet, goggles, safety boots, hand gloves, overall, apron sandbag, fire extinguishers, etc.

Identification and operation of various types of fire extinguishers

Accident: causes and prevention techniques.

First Aid – materials for First Aid, charts, posters and first aid box, etc

Application of first aid materials

Energy, matter and power

Energy

Nature of matter

Power

Temperature and pressure

Concept of temperature

Different types of thermometers, e.g., gas, resistance, liquid and thermocouple

Temperature scale conversion

• centigrade to Fahrenheit
• Celsius to Kelvin
• Fahrenheit to rankine

International practical temperature

• The boiling point of oxygen – 182.97^ºC
• The triple point of water – 0.01 ^ºC
• The boiling point of water – 100 ^ºC

Concept of pressure

Different types of pressure measuring devices, e.g., barometer, manometer, bourdon tube gauge.

• Demonstration of the use of a barometer

Pressure measurement

Uses of suction and high-pressure gauges

• Demonstrate how suction and high-pressure gauges are used to determine the performance of a refrigerant

Effects of temperature, pressure and volume in refrigeration and air conditioning systems

Gas law, Boyles law, Charles law and Dalton’s law

Calculations involving general gas law.  Formulae

• –   P₁ V₁ = P₂V₂
• –   P₁ =  P₂
• –   T₁     T₂
• –          V₁  = V₂
• –          T₁     T₂
• –          P₁ V₁ = P₂V₂
• –             T₁        T₂

Plotting various temperature scales

Refrigeration and air conditioning systems

Refrigeration cycle – Evaporation, compression, condensation and expansion

Layout diagram of refrigeration systems

Types and applications of the various forms of refrigeration

Principles of operation of forms of a refrigeration system

Functions of the component and accessories, e.g., relay, solenoid valves, capacitors and thermostat

Definition and types of refrigerants

• Identification of refrigerant by cylinder colours.

Chemical names and formulae

Properties and uses of refrigerants

Refrigerants flow controls, e.g., TEV, AEV, capillary tube

Operations of refrigerant flow controls

Psychometric properties of air.

• Demonstration of air conditioning principle by sling psychometer

The processes of air conditioning: heating and cooling

Latent and sensible heat, saturated and super-saturated vapour.

Demonstration of the difference between latent and sensible heat by use of methylated spirit on human skin

Compressors, Condenses and Evaporators

Types of compressors

Construction of compressors

Working principles of compressors

Construction of condensers

• Demonstrate how to service a condenser

Calculation of heat load on condensers

Types and functions of a liquid receiver and service valves

Principle of operation of a liquid receiver and service valves

Types of evaporators

Construction and services of evaporators

• Demonstrate how to service evaporators

Working principles of evaporators

Heat load estimates on evaporators

Workshop practices

Basic tools – hacksaw, coil spring benders, reamers, tube cutters, etc

Tools and procedures for servicing window unit air- conditioner

• Servicing of a window air-conditioner

Different methods of diagnosing faults: systematic and observation

Common faults in refrigeration systems and their symptoms – leakage, faulty units, faulty compressor, poor cooling and current leakage

Techniques of effective repairs in refrigeration and air - conditioning systems

Techniques of troubleshooting in a given system

Testing for leakages, polarity, insulation continuity, pressure and efficiency

• Demonstrate how to test for leakages, polarity continuity and efficiency

Maintenance of compressors, evaporators, motors, condensers, valves, accumulators and contactors

Demonstrate how to repair faults in compressors, evaporators, motors and condensers.

Installation processes

Concept of piping, ducting and trunking

Piping a condenser and an evaporator

Ducting, trunking and installation of air-conditioners

• Installation of a split air-conditioners

Piping, ducting and trunking tools – mallet hammer, flaring tools, silver tape, dot-punch, bending spring, amaflex, hacksaw, PVC pipes

Types, functions, operation and application of motors and generators

Installation procedures for motors and generators

Maintenance of motors and generators in a refrigeration system

• Servicing of motors and generators

Working principles of a cold room

Cold room installation procedures

Factors affecting cold room operations.

Insulation processes

Importance of insulation of refrigeration and air-conditioning systems

Types of insulating materials – glass wool, fibre glass, polystyrene foam, wood, bitumen, ceramic, etc

Functions and properties of insulation materials

Procedure for insulating refrigeration and air - conditioning systems

Entrepreneurship

Concept of business enterprise and types of businesses – sole proprietorship, partnership, limited liability, etc

Sources of finance – loan, mortgage, shares, overdrafts, savings, etc.

Types and functions of marketing styles

Meaningful marketing at the least cost

• • Carry out a commercial marketing survey to set up refrigeration and air-conditioning business

Marketing protocol and cost.

Principles of Accounting

The concept of business as a separate entity

Ledger, trial balance and balance sheet

• Preparation of ledger and balance sheet

LIST OF FACILITIES AND MAJOR EQUIPMENT/MATERIALS REQUIRED

1. Complete toolbox (RAC) –             3
2. Set of oxy-acetylene brazing equipment      –             2
3. Power pillar drilling machine –             1
4. Power grinding machine –             1
5. Portable hand drilling machine –             2
6. Portable table grinding machine –             2
7. Vacuum pump –             1
8. Recovery and recycling machine –             1
9. Spotter recovery pump –            2
10. Table vice –             4
11. Workbench –             2
12. Hand blower –             1
13. D. O. T. recovery cylinders big size   –             1
14. D. O. T. recovery cylinders (medium)         –   1
15. Manifold gauge                                                             –             2
16. Reamers –             4
17. Pipe benders (various sizes) spring and mechanical –             1
18. Ratchet wrenches –             2
19. Hacksaw –             4
20. Pliers (different types)                                                 –             1 each
21. Set of screwdrivers –             4
22. Mallet hammers –             2
23. Ball-pein hammer –             2
24. Electronic leak detectors –             1
25. Electronic charging scale –             2
26. Trolleys –             1
27. Halogen touch light –             1
28. Alcometer –             1
29. Various types of refrigerant (R134A, 600A and 717)

SUGGESTED READING LIST

Ananthranrayazan P. N. (2005) Basic refrigeration and air conditioning 3rd Edition, Tata McGraw Hill, New Delhi.

Whitman, W. C. Johnson, W. M. (1995) Refrigeration’s Air-conditioning Technology 3rd Edition, Delmar Publisher, Albany, N. Y.

Rajput R. K. (2006) Refrigerant and air-conditioning 1st Edition, S. K. Kataria and Sons, Naizarak, Delhi.

Roy J. Dossat. Principles of Refrigeration 4th Edition, Spectrum Publishers.