EPA Section 608 Technician Certification Study Guide

iWhat color are the gauges on a manifold gauge set? - yLow pressure is blue, High pressure is red. iWhat are the typical ranges of pressure measurements used on the gauges of a manifold gauge set? - yHigh side is 0 to 500 PSIG; Low side is 0 to 350 PSIG and 0 to 30 in. Hg below atmospheric pressure. iIs the refrigerant leaving a condenser at a high or low pressure? Is it a liquid or a gas? - yHigh pressure, liquid. iIs the refrigerant entering the expansion valve (variable metering device) a liquid or gas? - yLiquid, high pressure. iIs the pressure of the refrigerant entering the compressor high or low? - yLow pressure vapor. iWhere in a refrigerant circuit does a liquid boil to absorb heat? - yIn the evaporator. iThe refrigerant in the suction line is a gas that has been heated above its saturation. What is this condition called? - ySuperheated vapor. iWhat can cause liquid refrigerant to migrate to a compressor crankcase? - yIf the compressor is located in the coldest location in the circuit. iList two conditions that can quickly damage a compressor that is starting to run? - yOperating while in a deep vacuum or when the service valves are closed. iWhat system failures require taking an oil sample? - yA compressor burnout or if the unit has had a leak. iIs flushing with refrigerant an acceptable tube cleaning method? - yNo. iIn addition to preventing and repairing leaks what else should a technician do to conserve refrigerant? - yRecover and recycle used refrigerants. iWhat factors affect the speed of an evacuation? - yPump size, hose length, hose diameter, size of system to be evacuated, ambient temperature, suction line size, and the amount of moisture in the system. iHow should gauge set hoses be sized for use in evacuating a system? - yUse the shortest length and the largest diameter possible for the quickest evacuation. At least as large as the vacuum pump inlet. iWhen evacuating what is the benefit of using short hoses with large diameters? - yReduces emissions, pressure drop and evacuation time. iWhich connection determines the preferred size of hoses used with a vacuum pump? - yThe vacuum pump inlet. iAs the capacity and suction hose size increase what happens to the time needed for an evacuation? - yTime is reduced. iWhat purpose is served by heating a system during dehydration? - yTo speed up moisture removal. iDoes a thorough evacuation remove moisture from a system? - yYes. iWhat can happen to oil in the compressor if the moisture is left in an operating system? - yThe oil will form hydrofluoric and hydrochloric acids which will corrode the internal parts of the system. iWhat is the result of over-evacuating a system? - yNo damage will be done. iHow can a system be leak checked using a low pressure gauge? - yVacuum reading will rise when vacuum pump is turned off. iHow close should the vacuum gauge be connected to the vacuum pump during evacuation? - yAs far away as possible. iWhen measuring the vacuum of a system being evacuated the system must be isolated. What must be done to the vacuum pump? - yTurn it off and valve it off. iWhat is ozone? - y3 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. iHow much ozone can a chlorine atom destroy in the stratosphere? - yOne atom can destroy 100,000 ozone molecules. iWhat is Ozone Depletion Potential (ODP)? - yThe ability of any chemical to deplete the ozone layer. iWhat is CFC? - yChlorofluorocarbon. iWhich refrigerants are CFC's? - yR-11,12,113,114. iWhich chemical in the CFC refrigerants does the most damage to the ozone layer? - yChlorine. iWhat is an HCFC? - yHydrochlorofluorocarbons. iWhich refrigerants are HCFC's? - yR-22,123. iWhich is more harmful to the ozone layer a CFC or an HCFC? - yCFC's. iWhat is it about CFC's that make them more harmful to the stratosphere? - yChemical strength, they will not breakdown in the lower atmosphere. iWhat is an HFC? - yA fluorocarbon that contains no chlorine. iWhich refrigerants are HFC's? - yR-134a,404a,407c,410a. iWhat is the ODP of the HFC refrigerant? - yZero. iWhich refrigerants contain chlorine? - yCFC's and HCFC's. iWhich refrigerants have high ODP? - yCFC's.