By the end of this chapter, you will be able to:
Mastering these skills ensures you keep hydrocarbon RAC systems running safely and efficiently, protecting both people and the environment.
Installation and maintenance of hydrocarbon refrigerant air conditioning (RAC) systems require specialized knowledge of their classifications, charge size limitations, and fault identification techniques. This chapter focuses on maintaining hydrocarbon RAC systems in Kenya, where adherence to safety standards and environmental regulations is critical due to the flammable nature of hydrocarbons. Proper maintenance ensures system reliability, energy efficiency, and compliance with local laws such as the Environmental Management and Coordination Act (EMCA). Technicians working in hotels, hospitals, and commercial buildings must be proficient in detecting faults and understanding system limits to prevent hazards and costly downtime.
Hydrocarbon refrigerants, such as propane (R290) and isobutane (R600a), are gaining traction in Kenya due to their low global warming potential and energy efficiency. However, these refrigerants are flammable, requiring strict classification and charge size limitations to ensure safe installation and operation. Kenya’s occupational safety guidelines and international standards like IEC 60335-2-40 define these limits based on system type and location.
Hydrocarbon refrigerants are classified by their flammability and toxicity characteristics, which influence their safe use in RAC systems. The International Standard ISO 817 categorizes refrigerants by safety groups:
Hydrocarbon refrigerants’ classification as A3 means technicians must apply rigorous safety measures due to their high flammability. For instance, in a Nairobi hotel installing an R290 system, all electrical components must meet explosion-proof standards.
Charge size limits depend on the system’s application environment, such as domestic, commercial, or industrial settings. Kenyan regulations mirror international standards, restricting the maximum refrigerant charge to minimize fire risk:
Several factors determine the maximum permissible charge size for hydrocarbon RAC systems:
Installation and maintenance must align with Kenyan standards such as the KEBS codes and international standards like IEC 60335-2-40 and ISO 5149. Compliance ensures system safety, environmental protection, and eligibility for insurance coverage. For instance, county government offices installing hydrocarbon RAC units must provide certification of compliance to avoid penalties during audits.
Explain how hydrocarbon refrigerants are classified and why this classification is important in RAC system maintenance. (10 marks)
Discuss five factors that influence charge size limitations for hydrocarbon RAC systems in commercial installations. (10 marks)
Describe the typical charge size limitations for domestic and commercial hydrocarbon refrigeration units in Kenya. (10 marks)
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Create a free accountThis chapter covers the classifications and charge size limitations essential for safe handling of hydrocarbon RAC systems. It details the identification of common faults such as leaks, high current, underperformance, unusual noise, and vibrations, providing a basis for effective fault diagnosis techniques. The procedures for recovering hydrocarbon refrigerants and the proper storage of recovered refrigerants are thoroughly explained to ensure environmental safety and system integrity. Guidance on replacing and refurbishing worn-out parts and components is provided alongside methods for repairing refrigerant leaks. The chapter also highlights the importance of conducting pressure tightness and pressure strength tests to verify system reliability. System evacuation and refrigerant flushing using oxygen-free dry nitrogen are described, emphasizing the safe use of vacuum pumps during these processes. Finally, it addresses hydrocarbon refrigerant charging, methods for accessing and sealing hydrocarbon systems, and the necessary preparations for system maintenance to ensure optimal performance and safety.
Type: Individual
| Tools & Equipment | Materials |
|---|---|
| Digital weighing scale | Hydrocarbon RAC system manuals and datasheets |
| Calculator | Refrigerant charge size calculation charts (KS ISO 5149-3:2017) |
| Pen and notebook | Personal Protective Equipment (PPE) - overall/dust coat, safety boots, gloves, safety goggles |
| S/N | Item | Quantity |
|---|---|---|
| 1 | Hydrocarbon RAC system manuals and datasheets | 1 set per Candidate |
| 2 | Digital weighing scale | 1 per Candidate |
| 3 | Refrigerant charge size calculation charts (KS ISO 5149-3:2017) | 1 per Candidate |
| 4 | Calculator | 1 per Candidate |
| 5 | Pen and notebook | 1 set per Candidate |
| 6 | Personal Protective Equipment (PPE) - overall/dust coat, safety boots, gloves, safety goggles | 1 set per Candidate |
| Items to be Evaluated | Marks Available | Marks Obtained | Comments |
|---|---|---|---|
| TASK 1: PPE and Safety Compliance | |||
| Wore appropriate PPE (overall/dust coat, safety boots, gloves, safety goggles) (Award 1 mark for correct PPE worn, or zero) | 1 | ||
| Handled tools and equipment safely and correctly (Award 2 marks for correct handling and safety observance, or zero) | 2 | ||
| Sub-Total | 3 | ||
| TASK 2: Classification of Hydrocarbon RAC Systems | |||
| Identified and described three hydrocarbon RAC systems from manuals/datasheets (Award 1 mark per correctly identified and described system, max 3 marks) | 3 | ||
| Explained the classification criteria (e.g., A3 flammability, system type) (Award 2 marks for clear, accurate explanation, or zero) | 2 | ||
| Sub-Total | 5 | ||
| TASK 3: Determination of Charge Size Limits | |||
| Used KS ISO 5149-3:2017 charts correctly to calculate charge size limits for each system (Award 1.33 marks per correctly calculated charge size, max 4 marks) | 4 | ||
| Performed calculations accurately with calculator (Award 3 marks for accurate and complete calculations, or zero) | 3 | ||
| Sub-Total | 7 | ||
| TASK 4: Reporting and Documentation | |||
| Prepared a clear and concise report summarizing classifications and charge size limits (Award 3 marks for completeness and clarity, or zero) | 3 | ||
| Sub-Total | 3 | ||
| PRODUCT CHECKLIST | |||
| Report correctly classifies three hydrocarbon RAC systems with accurate charge size limits (in kg) (Award 5 marks for correct classification and accurate charge size limits, or zero) | 5 | ||
| Calculations match KS ISO 5149-3:2017 standards and show correct application of charge size limits (Award 4 marks for accurate, well-presented calculations, or zero) | 4 | ||
| Sub-Total | 9 | ||
| GRAND TOTAL | 27 | ||
Type: Individual
| Tools & Equipment | Materials |
|---|---|
| Leak detector suitable for hydrocarbons | Functional hydrocarbon RAC system |
| Multi-meter | Safety boots |
| Manifold gauge set with hoses | Dust coat/overall |
| Digital thermometer | Safety goggles |
| Sound level meter | Insulated gloves |
| Vibration meter | |
| Set of insulated hand tools (screwdrivers, pliers, spanners) |
| S/N | Item | Quantity |
|---|---|---|
| 1 | Functional hydrocarbon RAC system | 1 per workstation |
| 2 | Leak detector suitable for hydrocarbons | 1 per workstation |
| 3 | Multi-meter | 1 per candidate |
| 4 | Manifold gauge set with hoses | 1 per workstation |
| 5 | Digital thermometer | 1 per candidate |
| 6 | Sound level meter | 1 per workstation |
| 7 | Vibration meter | 1 per workstation |
| 8 | Set of insulated hand tools (screwdrivers, pliers, spanners) | 1 set per candidate |
| 9 | Safety boots | 1 pair per candidate |
| 10 | Dust coat/overall | 1 per candidate |
| 11 | Safety goggles | 1 per candidate |
| 12 | Insulated gloves | 1 pair per candidate |
| Items to be Evaluated | Marks Available | Marks Obtained | Comments |
|---|---|---|---|
| TASK 1: Safety and Preparation | |||
| Wore appropriate PPE including dust coat, safety boots, goggles, and insulated gloves (Award 1 mark for full compliance or zero) | 1 | ||
| Handled tools and equipment safely and correctly (Award 2 marks for correct and safe use or zero) | 2 | ||
| Sub-Total | 3 | ||
| TASK 2: Fault Identification - Leak Detection | |||
| Set up and operated hydrocarbon leak detector as per manufacturer instructions (Award 1 mark for correct setup and operation or zero) | 1 | ||
| Inspected all pipe joints, flare nuts, and brazed joints for leaks (Award 2 marks for thorough inspection or zero) | 2 | ||
| Reported presence or absence of leaks accurately (Award 1 mark for correct reporting or zero) | 1 | ||
| Sub-Total | 4 | ||
| TASK 3: Electrical Fault Detection | |||
| Isolated power supply to the RAC system before electrical checks (Award 1 mark for correct isolation or zero) | 1 | ||
| Checked electrical current and voltage using multi-meter (Award 2 marks for correct measurement and interpretation or zero) | 2 | ||
| Identified and reported any high current or electrical faults (Award 1 mark for correct fault identification or zero) | 1 | ||
| Sub-Total | 4 | ||
| TASK 4: Performance and Noise/Vibration Inspection | |||
| Measured system operating parameters including pressures and temperatures using manifold gauges and thermometers (Award 2 marks for correct measurement or zero) | 2 | ||
| Checked for unusual noises using sound level meter and reported findings (Award 1 mark for correct noise identification or zero) | 1 | ||
| Checked for abnormal vibrations using vibration meter and reported findings (Award 1 mark for correct vibration identification or zero) | 1 | ||
| Sub-Total | 4 | ||
| TASK 5: Reporting and Housekeeping | |||
| Prepared a detailed fault identification report in line with workplace procedures (Award up to 5 marks for completeness and accuracy or zero) | 5 | ||
| Performed housekeeping by cleaning and storing tools and clearing the work area (Award 1 mark for proper housekeeping or zero) | 1 | ||
| Sub-Total | 6 | ||
| PRODUCT CHECKLIST | |||
| Fault identification report clearly detailing leaks, electrical faults, performance issues, and abnormal noise/vibration (Award up to 5 marks for clarity, accuracy, and completeness or zero) | 5 | ||
| Sub-Total | 5 | ||
| GRAND TOTAL | 26 | ||
At the start of this chapter we promised you would be able to:
Tick each one you can genuinely do.
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