HVAC Certification Core
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What are the main components of the Vapor/Compression Refrigeration Cycle?
- Metering device, reduction in pressure
- Evaporator, heat is absorbed, causing liquid to boil into a vapor
- Compressor, refrigerant is now a low temperature low pressure vapor
- Condenser, refrigerant is now a high temperature high pressure vapor
- Condenser Outlet, as the refrigerant expels heat it condenses to a liquid and becomes a high pressure liquid
What are the four categories of technician certification?
Type I, Type II, Type III, Universal
Name the causes of the depletion of the Ozone resulting in the use of CFCs, and HCFCs.
Crop Loss, Increase in Eye Dieseases, Skin Cancer, Reduced Marine Life, Deforestation, Increased Ground Level Ozone
What are the elements of CFCs?
Chlorine, Fluorine, Carbon
Types: R-11, 12, 500
What are the elements of HCFCs?
Hydrogen, Chlolrine, Fluorine, Carbon
Types: R-22, 123
What are the elements of HFCs?
Hydrogen, Fluorine, Carbon
What is the Clean Air Act?
Regulation set forth by the US Governement for section 608
Name violations of the Clean Air Act.
- Falsify, fail to keep records
- Fail to reach required evacuation rates
- Knowingly vent CFCs, HCFCs, or HFCs
- Work without certification
- Fail to recover CFCs, HCFCs, or HFCs
- Fail to have approved recovery devices
- Add nitrogen to a fully charged system
- Dispose of cylinder without recovering regrigerant
What resulted from the Montreal Protocol?
- Phase out of production of Ozone depleting substances in developed countries
- CFCs were phased out on Dec 31,1995
- Future supplies will come from recovered, recycled, or reclaimed refrigerants
State the three "R's" and what each means.
- Recover, to remove refrigerant in any condition from a system and store it externally
- Recycle, to clean refrigerant for reuse by separating the oil and removing moisture by passing it through filters
- Relaim, to process refrigerant to a level equal to virgin product standards (must meet the standard set forth in ARI 700 before it is sold)
Name the types of recovery devices.
- System Dependent
- Self Contained
What is R-134a a substitute for?
- CFC R-12
- R-134a is considered Ozone friendly, and can be used in most R-12 systems
- Must use pressurized nitrogen when testing for leaks
What does ternary mean?
A blend of three parts, used with a synthetic alkylbenzene lubricant
What is important to know about blends?
- The components of a blended refrigerant will leak from a system at uneven rates due to different vapor pressures
- Proper charging method for blended refrigerants is to weigh into the high side of the system liquid
- Temperature Glide, refers to a refrigerant blend that has a range of boiling points or condensing points throughout the evaporator and condenser respectively
Who is allowed to buy CFC and HCFC refrigerants?
Sale is restricted to certified technicians, and only those certified in Section 609 can purchase containers smaller than 20 pounds
What are some of the requirements for Recovery Techniques?
- It is the Law
- If more than one refrigerent has been mixed in a system, you must recover the mixture in a separate tank
- When recovering from a system that experienced a compressor burn out, watch for signs of contamination in the oil
- Nitrogen may be legally vented, after checking for leaks
- Length of the hose between the unit being recovered from and the recovery machine will greatly effect the efficiency of the process, long hoses will cause excessive pressure drop and recovery time
- Guard against trapping liquid refrigerents between the service valves
How would you determine where a leak is located?
Use an electronic or ultrasonic leak detector to determine the general area, the use soap bubbles to pinpoint the leak
Why are dehydration procedures through evacuation important to follow?
- Dehydration is used to remove water and water vapor
- If moisture is allowed to remain in a system, hydrochloric and hydrofluoric acids may form
What must you do before evacuating a system?
Be sure you attain the mandated vacuum level before evacuating the system to the ambient air
What factors contribute to the speed and effciency of evacuation?
- Size of equipment being evacuated
- Ambient temperature
- Amount of moisture in the system
- Size of vacuum pump and suction line
What are some important things to remember when vacuuming a system?
- Piping connection to the pump should be as short as possible and as large in diameter as possible
- System vacuum gauge should be connected as far as possible from the vacuum pump
- Measuring a systems vacuum should be done with the system isolated and the pump turned off
What are some of the characteristics of Recovery Cylinders?
- Specifically designed to be refilled
- Have 2 ports, one liquid and one vapor
- EPA requires that a refillable cylinder MUST NOT BE FILLED ABOVE 80% of its capacity by weight
- Must be hydrostatically tested and date stamped every 5 years
Refillable cylinders used for transporting recovered pressurized refrigerant must be approved by what department?
- DOT(Department of Transportation)
- Must also be identified by their colors, yellow tops and gray bodies.
- Must also be inspected for rust, if present they should be reduced to 0 psig and discarded
What should you be aware of as far as safety measures?
- Wear safety glasses, protective gloves, and follow all equipment manufacturers safety precautions
- Always charge through a pressure regulator and insert a relief valve downstream from the pressure regulator
- Relief valves MUST NOT be installed in series, and MUST be replaced if there is a corrosion build up
Describe a Schrader valve.
- It is critical to inspect the valve core for leaks, bends and breakage, replace damaged valve cores to prevent leakage and always cap ports to prevent accidental depression of the core
- NEVER heat a refrigerant cylinder with an open flame, do not cut or braze lines on a charged unit
In the event of a large release of refrigerant in a confined area, what action do you take?
- Don an SCBA, IMMEDIATELY VACATE AND VENTILATE the area
- Never expose R-12 or R-22 to open flames or glowing hot metal surfaces, they can decompose to form hydrocholoric acid, hydrofluoric acid, and phosgene gas
- Always read MSDS when working with solvents, chemicals or refrigerants
What action should be taken before transporting cylinders?
- Meets DOT standards
- Complete shipping paperwork
- Properly label cylinders
- Should be upright and marked with a DOT clasification tag indicating "2.2 non-flammable gas"
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