Test 1 Flashcards
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?
The 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.
All of the above.
All of the above
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
