EPA Section 608 Technician Certification Study Guide

EPA Section 608 Technician Certification Study Guide What are the typical uses of the center port of gauge set? - Used during evacuation, charging and recovery procedures. What color are the gauges on a manifold gauge set? - Low pressure is blue, High pressure is red. What are the typical ranges of pressure measurements used on the gauges of a manifold gauge set? - High side is 0 to 500 PSIG; Low side is 0 to 350 PSIG and 0 to 30 in. Hg below atmospheric pressure. Is the refrigerant leaving a condenser at a high or low pressure? Is it a liquid or a gas? - High pressure, liquid. Is the refrigerant entering the expansion valve (variable metering device) a liquid or gas? - Liquid, high pressure. Is the pressure of the refrigerant entering the compressor high or low? - Low pressure vapor. Where in a refrigerant circuit does a liquid boil to absorb heat? - In the evaporator. The refrigerant in the suction line is a gas that has been heated above its saturation. What is this condition called? - Superheated vapor. What can cause liquid refrigerant to migrate to a compressor crankcase? - If the compressor is located in the coldest location in the circuit. List two conditions that can quickly damage a compressor that is starting to run? - Operating while in a deep vacuum or when the service valves are closed. What system failures require taking an oil sample? - A compressor burnout or if the unit has had a leak. Is flushing with refrigerant an acceptable tube cleaning method? - No. In addition to preventing and repairing leaks what else should a technician do to conserve refrigerant? - Recover and recycle used refrigerants. What factors affect the speed of an evacuation? - Pump size, hose length, hose diameter, size of system to be evacuated, ambient temperature, suction line size, and the amount of moisture in the system. How should gauge set hoses be sized for use in evacuating a system? - Use the shortest length and the largest diameter possible for the quickest evacuation. At least as large as the vacuum pump inlet. When evacuating what is the benefit of using short hoses with large diameters? - Reduces emissions, pressure drop and evacuation time. Which connection determines the preferred size of hoses used with a vacuum pump? - The vacuum pump inlet. As the capacity and suction hose size increase what happens to the time needed for an evacuation? - Time is reduced. What purpose is served by heating a system during dehydration? - To speed up moisture removal. Does a thorough evacuation remove moisture from a system? - Yes. What can happen to oil in the compressor if the moisture is left in an operating system? - The oil will form hydrofluoric and hydrochloric acids which will corrode the internal parts of the system. What is the result of over-evacuating a system? - No damage will be done. How can a system be leak checked using a low pressure gauge? - Vacuum reading will rise when vacuum pump is turned off. How close should the vacuum gauge be connected to the vacuum pump during evacuation? - As far away as possible. When measuring the vacuum of a system being evacuated the system must be isolated. What must be done to the vacuum pump? - Turn it off and valve it off. What is ozone? - 3 atoms of oxygen. It blocks much of the harmful ultraviolet radiation (uv-b) emitted from the sun and it keeps our earth's temperature stable. How much ozone can a chlorine atom destroy in the stratosphere? - One atom can destroy 100,000 ozone molecules. What is Ozone Depletion Potential (ODP)? - The ability of any chemical to deplete the ozone layer. What is CFC? - Chlorofluorocarbon. Which refrigerants are CFC's? - R-11,12,113,114. Which chemical in the CFC refrigerants does the most damage to the ozone layer? - Chlorine. What is an HCFC? - Hydrochlorofluorocarbons. Which refrigerants are HCFC's? - R-22,123. Which is more harmful to the ozone layer a CFC or an HCFC? - CFC's. What is it about CFC's that make them more harmful to the stratosphere? - Chemical strength, they will not breakdown in the lower atmosphere. What is an HFC? - A fluorocarbon that contains no chlorine. Which refrigerants are HFC's? - R-134a,404a,407c,410a. What is the ODP of the HFC refrigerant? - Zero. Which refrigerants contain chlorine? - CFC's and HCFC's. Which refrigerants have high ODP? - CFC's. Which refrigerants have low ODP? - HCFC's, HFC's are zero. What is an azeotrope refrigerant? - A mixture of two or more compounds where the mixture behaves like a single chemical. Is one of the components of R-500 a CFC? - Yes Does stratospheric ozone help or hurt the work of the earth's protective shield? - It helps. What chemical in the stratosphere tells us ozone depletion is occurring? - Chlorine-monoxide. How do we know the chlorine in the stratosphere is coming from CFC's? - The increase in chlorine and fluorine present in the stratosphere, matches the increase in emissions of CFC's. How do we know CFC's get to the stratosphere? - From high altitude air sampling measurements. What role does the ozone layer play in protecting the earth? - It blocks much of the harmful ultraviolet radiation (uv-b). What are the effects on health from increased ultraviolet radiation? - Skin cancer, cataracts, human immunity is reduced. What are the effects on the environment? - Timber growth is reduced, crop yields lowered, marine life and the food chain are impaired. Is ozone depletion a problem for the United States only or a global problem? - A global problem. What is the Montreal Protocol? - A treaty that called for the reduction of production of CFC's. The Montreal Protocol calls for the regulation of what chemicals? - Ozone depleting compounds, CFC's, HCFC's, and Halons. On what date was the production and importation of all CFC's phased out? - In the U.S., after December 31, 1995. Where will we get replacements? - Through recovery of existing refrigerants. What steps are called for by the Clean Air Act? - Taxes on production and use, standards set for the recovery of refrigerants. What is prohibited by the Clean Air Act? - Venting. Do state and local laws have priority over federal law? Can they be less strict? - No. Cities or states can create their own laws but they must be at least as strict as federal laws. To prevent damage to the ozone layer the U.S. is making laws to capture the CFC's now in use. What else does the new law do to restrict the release of CFC's? - Allows states and municipalities to create their own laws to prevent and monitor the release of CFC and HCFC materials into the atmosphere.