click below
click below
Normal Size Small Size show me how
Cfc type 2 #2
| Question | Answer |
|---|---|
| Heat pumps that use R-410A should be leak checked with | pressurized nitrogen |
| Heat pumps that have been retrofitted from R-22 to R-407C should be leak checked with | pressurized nitrogen |
| To change the compressor on a system containing R-410A, you must isolate the compressor and then | evacuate the isolated section of the system to atmospheric pressure and hold. If the system pressure does not rise, remove the compressor. |
| The method to charge a system that has a normal charge of 80 pounds is to charge with | liquid through the liquid line service valve |
| After installation of a field-piped R-410A split heat pump, the unit should first be | pressurized with nitrogen, then leak checked |
| Pressure relief valves must not be . | installed in series |
| When charging an R-12 refrigeration system that uses a water-cooled condenser, you must first charge with vapor to a pressure of at least _____ before switching to liquid charging. | 35 psig |
| Your recovery/recycling machine has R-22 refrigerant in it. You now have to recover refrigerant from a unit with R-410A. What must be done before your recovery unit can be used to recover R-410A? | recovery unit must be EPA-certified for use with R-410A. The recovery tank must be designed for the pressure of R-410A. The filter and lubricant in the recovery unit must be changed and the recovery unit evacuated. |
| After reaching the required recovery vacuum on a system you must | wait to see if the system pressure rises indicating that there is still refrigerant in liquid form or refrigerant trapped in the oil. |
| In a refrigeration system, the component directly following the evaporator is the | accumulator |
| A reciprocating compressor should not be energized while | the discharge service valve is closed |
| R-410A requires a high-pressure manifold gauge and hose set. They must have a | 4000 psig burst pressure and a 800 psig working pressure. |
| The refrigerant pressure inside an R-410A unit which is at room temperature (72F) and not operating is | approximately 210 psig. |
| Every air conditioning or refrigeration system should be protected by a | pressure relief device. |
| . To change the compressor on a system containing 40 pounds of R-500 using a recycling machine that was manufactured AFTER November 15 1993, you must isolate the compressor then | evacuate the isolated section of the system to 10 inches of vacuum and hold. If system pressure does not rise, remove the compressor. |
| When inspecting a system for leaks, you should look for | traces of oil. |
| When a new system has been assembled, the first thing to do is | pressurize the system with an inert gas and leak check. |
| R-410A is different from other ASHRAE 400 series non-azeotropic blends because | R-410A behaves as a near azeotropic refrigerant and can be topped off. |
| Manifold gauge set hoses should have self-sealing connectors or hand valves to | minimize the release of refrigerant when the hoses are connected and disconnected |
| When using recovery or recycling equipment that was manufactured AFTER November 15 1993, you must evacuate a system containing MORE than 200 pounds of CFC-12 to _______ before making a major repair. | 15 inches of Hg vacuum |
| With an air-cooled condenser on the roof of a building and the evaporator on the first floor, recovery should first occur | from the liquid line entering the evaporator |
| Never use oxygen or compressed air to leak check equipment because R-410A can | explode when mixed with air or oxygen |
| Dry nitrogen should be used to break the first vacuum when dehydrating by the double evacuation method. However, it | can be dangerous if not used with a pressure regulator. |
| A recovery machine that uses a hermetic compressor will overheat when drawing a deep vacuum because | the motor needs the flow of refrigerant through the compressor to provide motor cooling. |
| The proper charging method for blended (non-azeotropic) refrigerants (400 series) is to remove the charge from the cylinder as a | liquid |