It is best practice to use dry nitrogen to break the vacuum when dehydrating by the triple evacuation method. However, it;

• often contains moisture

• requires a minimum of 10 psig

• is toxic when released into the environment

• requires a pressure regulator

When can appliances containing refrigerants be recovered to atmospheric pressure?

• for major repairs such as replacing the compressor , condenser, or evaporator

• the repair is followed by an evacuation of the appliance to the environment

• leaks in the appliance make recovery to the prescribed level unattainable

• the appliance is being disposed of and recycled

Which of the following repairs would always be considered "major" under EPA's regulations

• Replacement of an evaporator coil

• Replacement of a filter-drier

• Replacement of a Schrader valve core

• Replacement of a condenser fan motor

Before making a major repair, technicians must evacuate an appliance or component containing more than 200 pounds of R-410A to which of the following levels?

• 0 PSIG

• 25mm Hg absolute

• 10 inches of Hg vacuum

• 15 inches of Hg vacuum

How can you speed up the removal of the refrigerant charge from a system?

• using a smaller recovery vessel

• cooling the recovery cylinder to lower it's pressure

• using a two-stage vacuum pump

• heating the recovery cylinder to raise it's pressure

You are changing out the compressor of a system containing 40 pounds of R-404A. In addition to isolating the compressor, which of the following procedures should you follow?

• simply remove the compressor and cap the ends

• evacuate the isolated section of the system to atmospheric pressure, then remove the compressor

• evacuate the isolated section of the system to 0 PSIG and if system pressure does not rise after a few minutes remove the compressor

• evacuate the isolated section of the system to 18" Hg and if system pressure does not rise after a few minutes energize the compressor

How would you remove moisture from refrigerant in a system?

• purge the condenser

• drain the oil seperator

• reduce water flow to the condenser

• use a filter-drier

Why could a recycling or recovery machine that uses a hermetic compressor overheat when drawing deep vacuums?

• it runs faster than other equipment with oil-less compressors

• the motor relies on the flow of refrigerant through the compressor for cooling.

• it has a higher compression ratio limit than other equipment

• the oils used in hermetic compressors are a lower viscosity than the oils used in other equipment

Which part of a belt driven non-hermetic compressor is most likely to leak if the compressor is not been used for several months?

• suction service valve

• rotating shaft seal

• one or both of the king valves

• head gaskets on discharge side

What is the state of the refrigerant leaving the receiver in a refrigeration system?

• low pressure liquid

• low pressure vapor

• high pressure liquid

• high pressure vapor