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WorksheetsType 2 Test 1
Total questions: 25
Worksheet time: 13mins
Heat pumps that use R-410A should be leak checked with
HFCs
HCFCs to lower the cost of discarding the refrigerant.
pressurized nitrogen.
compressed oxygen.
Heat pumps that have been retrofitted from R-22 to R-407C should be leak checked with
HFCs
HCFCs
pressurized nitrogen.
compressed air.
To change the compressor on a system containing R-410A, you must isolate the compressor and then
simply remove the compressor.
evacuate the isolated section of the system to atmospheric pressure and hold. If the system pressure does not rise, remove the compressor.
evacuate the isolated section of the system to 10 inches of vacuum and hold. If the system pressure does not rise, remove the compressor.
evacuate the isolated section of the system to 15 inches of vacuum and hold. If the system pressure does not rise, remove the compressor.
Which of the following is the correct way to charge a refrigeration system?
vapor through the suction line service valve.
liquid through the discharge service valve.
liquid through the suction service valve.
liquid through the liquid line service valve.
After installation of a field-piped R-410A split heat pump, the unit should first be
evacuated.
pressurized with R-22, then leak checked.
pressurized with R-410A, then leak checked.
pressurized with nitrogen, then leak checked.
Pressure relief valves must not be
installed in series.
installed in parallel.
installed vertically.
installed in horizontally.
What is the required recovery vacuum for a system?
10 psig
20 psig
35 psig
100 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.
After reaching the required recovery vacuum on a system you must
immediately disconnect the recovery or recycling equipment and open the system for service.
immediately break the vacuum with nitrogen and open the system for service.
immediately pressurize the system with nitrogen and perform a leak check.
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
receiver.
metering device.
accumulator.
condenser.
A reciprocating compressor should not be energized while
the discharge service valve is closed.
the suction service valve is open.
the discharge service valve is open.
there is a demand for cooling.
R-410A requires a high-pressure manifold gauge and hose set. They must have a
2000 psig burst pressure and a 400 psig working pressure.
2000 psig burst pressure and a 800 psig working pressure.
4000 psig burst pressure and a 400 psig working pressure.
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 74 psig.
approximately 110 psig.
approximately 210 psig.
approximately 310 psig.
Every air conditioning or refrigeration system should be protected by a
pressure relief device.
properly located stop valve.
low-pressure control.
refrigerant receiver.
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
simply remove the compressor.
evacuate the isolated section of the system to atmospheric pressure, then remove the compressor.
evacuate the isolated section of the system to 10 inches of vacuum and hold. If system pressure does not rise, remove the compressor.
evacuate the isolated section of the system to 15 inches of vacuum and hold. If system pressure does not rise, remove the compressor.
When inspecting a system for leaks, you should look for
frost on the pipes.
puddles of liquid refrigerant.
particles from the drier core.
traces of oil.
When a new system has been assembled, the first thing to do is
evacuate the system.
pressurize the system with an inert gas and leak check.
pressurize the sytem with refrigerant to be used in the system.
introduce an initial charge of refrigerant and start the compressor.
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.
R-410A is an HCFC.
R-410A uses mineral oil.
All of the above.
Manifold gauge set hoses should have self-sealing connectors or hand valves to
minimize the chance of an explosion during use.
prevent venting during recycling.
prevent a vapor lock during rapid liquid transfer.
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.
0 psig
4 inches of Hg vacuum
10 inches of Hg vacuum
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 vapor line entering the condenser,
from the discharge side of the compressor.
from the liquid line entering the evaporator.
on the suction side of the compressor.
Never use oxygen or compressed air to leak check equipment because R-410A can
explode when mixed with air or oxygen.
fractionate when mixed with oxygen.
condense when exposed to oxygen.
None of the above.
Dry nitrogen should be used to break the first vacuum when dehydrating by the double evacuation method. However, it
often contains moisture.
is expensive.
is toxic.
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
it runs faster than other equipment.
the motor needs the flow of refrigerant through the compressor to provide motor cooling.
the oils used in hermetic compressors burn at lower temperatures.
it has a higher compression ratio limit than other equipment.
The proper charging method for blended (non-azeotropic) refrigerants (400 series) is to remove the charge from the cylinder as a
vapor.
liquid.
superheated vapor.
subcooled liquid.
