SOLAS Refrigeration study plan
SOLAS Refrigeration · Give each week a clear focus.
8 weeks · About 6 hours per week
Refrigeration and Air Conditioning (craft apprenticeship curriculum)
Explain the vapour-compression cycle stage by stage (compression, condensation, expansion, evaporation) and state the pressure and phase condition of the refrigerant at each point.
Identify on a labelled sketch the compressor, condenser, expansion device, evaporator, receiver, and suction/liquid lines of a typical marine refrigeration plant.
Define sensible heat, latent heat, superheat, subcooling, and saturation temperature, and calculate superheat and subcooling from given gauge readings and a pressure-temperature chart.
Convert between gauge and absolute pressure and between Celsius and Kelvin, showing working for at least ten practice conversions.
State the function of the compressor oil and describe how oil is returned to the crankcase.
Your checkpoint
A hand-drawn, fully labelled vapour-compression cycle diagram with a one-page written explanation of each stage, plus ten worked pressure/temperature and superheat/subcooling calculations scored at 80% or better on self-marking.
Refrigeration and Air Conditioning (craft apprenticeship curriculum)
Describe the construction and operating principle of reciprocating, scroll, and screw compressors used in marine refrigeration, listing two advantages and two limitations of each.
Explain the purpose and operation of capacity control methods: cylinder unloading, variable speed, and hot-gas bypass.
Describe the shell-and-tube and fin-and-tube condenser and evaporator constructions and explain how seawater flow, fouling, and air ingress affect performance.
Outline the function of thermostatic and electronic expansion valves, including how superheat setting changes valve opening.
Identify the safety devices fitted to a refrigeration circuit (high/low pressure cut-outs, oil pressure switch, relief valves) and state the condition each protects against.
Your checkpoint
A comparison table of at least three compressor types and two evaporator/condenser types, with advantages, limitations, and typical applications, plus a one-page description of how each safety cut-out protects the plant.
Refrigeration and Air Conditioning (craft apprenticeship curriculum)
Explain the function of the receiver, filter-drier, sight glass, liquid line solenoid, and suction accumulator in the circuit and describe the symptom of a blocked filter-drier.
Describe how moisture, air, and non-condensable gases enter a system and explain the faults each causes.
Explain the principles of leak detection using pressure testing, soap solution, and electronic detectors, and state why open flame testing is not acceptable on modern refrigerants.
Describe the evacuation procedure, including the purpose of a vacuum and the use of a vacuum gauge and triple evacuation.
State the charging methods (by weight, by superheat, by subcooling) and when each is appropriate.
Your checkpoint
A written procedural checklist for leak testing, evacuation, and charging a system, with the acceptance criteria (vacuum level held, superheat target) stated for each step.
Refrigeration and Air Conditioning (craft apprenticeship curriculum)
Interpret a pressure-enthalpy diagram and identify the compression, condensation, expansion, and evaporation lines for a given operating condition.
Calculate refrigeration effect, mass flow of refrigerant, and coefficient of performance from given enthalpies.
Explain how suction pressure, discharge pressure, and condenser seawater temperature affect capacity and power consumption.
Diagnose at least five common faults (low charge, overcharge, restricted liquid line, faulty expansion valve, inefficient compressor) from a set of gauge and temperature readings.
Describe the pump-down procedure and explain why it is used before maintenance.
Your checkpoint
A worked fault-diagnosis exercise: five fault scenarios each with gauge, temperature, and sight-glass observations, with the diagnosis, reasoning, and corrective action written out and self-marked against reference notes.
Refrigeration and Air Conditioning (craft apprenticeship curriculum)
Describe the properties, handling, and environmental obligations for common refrigerants (R134a, R404A, R407C, R717 ammonia) including GWP and ozone-depletion considerations.
State the safety precautions for ammonia systems, including personal protective equipment, detection, and emergency shutdown.
Explain the requirements for refrigerant recovery, record keeping, and preventing deliberate release.
Describe the effect of refrigerant blends on charging (liquid charging) and on leak repair.
Identify the hazards of frostbite, asphyxiation in machinery spaces, and high-pressure liquid injection.
Your checkpoint
A one-page refrigerant handling and safety summary covering four refrigerants, their hazards, GWP ranking, and the correct recovery and record-keeping steps, checked against the notes for accuracy.
Refrigeration and Air Conditioning (craft apprenticeship curriculum)
Explain the components and operation of a marine air-conditioning system, including the chilled-water circuit, air-handling unit, and cooling coil.
Describe how to measure and adjust supply air temperature, humidity, and airflow, and state typical comfort targets.
Explain the causes and remedies of coil icing, condensate drainage problems, and poor airflow.
Describe the interaction between the air-conditioning seawater cooling circuit and the refrigeration plant and how to isolate one without affecting the other.
Outline a preventive maintenance schedule for filters, coils, drains, and refrigerant charge checks.
Your checkpoint
A preventive maintenance schedule table for an air-conditioning system listing task, frequency, acceptance criterion, and the fault it prevents, covering at least eight tasks.
Refrigeration and Air Conditioning (craft apprenticeship curriculum)
Explain the purpose and operation of automatic controls: thermostats, pressure switches, solenoid valves, and defrost timers.
Describe how to prove a control circuit safe before working on it, including isolation and lock-off.
Explain the function of the oil separator, oil level control, and crankcase heater and the fault caused by a failed crankcase heater.
Describe a defrost cycle and explain how to recognise a failed defrost termination.
Outline the procedure for safely isolating, depressurising, and restarting a refrigeration system after repair.
Your checkpoint
A written isolation-and-restart procedure for a refrigeration system with numbered steps, safety checks at each stage, and a list of the controls that must be proved before returning the plant to service.
Refrigeration and Air Conditioning (craft apprenticeship curriculum)
Consolidate all earlier material by answering at least 60 practice questions across the whole domain and reviewing every wrong answer.
Re-derive superheat, subcooling, and COP calculations without notes to confirm retention.
Explain aloud, without notes, the full vapour-compression cycle, the main components, and three fault diagnoses.
Review the weakest two topics identified in practice and rewrite the relevant notes into a one-page summary each.
Plan the exam-day approach: time allocation, question order, and how to handle calculation questions.
Your checkpoint
A timed 60-question mock test scored at 80% or better, plus a one-page personal error log listing each mistake, its cause, and the corrected fact.
Milestones
Week 2: Without notes, name the four cycle stages, the component for each, and two compressor types with one advantage and one limitation each; score at least 8 of 10 on a self-made recall quiz.
Week 4: Correctly diagnose at least four of five fault scenarios from gauge and temperature data and show working for a COP and refrigeration-effect calculation without reference material.
Week 6: Explain refrigerant handling, recovery, and ammonia safety precautions in a five-minute verbal run-through, and produce the air-conditioning maintenance table with at least eight complete rows.
Week 8: Score 80% or better on a timed 60-question mock test and complete the error log with a corrected fact for every wrong answer.