EPA II Flash Flashcards
Testing with soap bubbles is used:
to pinpoint refrigerant leaks
Many refrigeration units use an open compressor. Which part of the compressor is most likely to leak if a unit is not used for several months?
The rotating shaft seal
When a new system has been assembled (built-up), and is ready for testing, the first thing to do is:
Pressureize with an inert gas and leak check
EPA regulations require that all appliances containing more than 50 pounds of refrigerant, except commercial and industrial process refrigeration, be repaired when the leak rate exceed what percent of the charge per year?
15 percent
When using recovery and recycling equipment manufactured AFTER 11/15/1993, techs must evacuate an appliance component containing more than 200 pounds of CFC-12 to the following level before making a major repair:
15 inches of Hg vacuum
Appliances containing CFC refrigerants can be evacuated to atmospheric pressure when:
Leaks in the appliance make evacuation to the prescribed level unattainable
When using recovery and recycling equipment manufactured BEFORE 11/15/1993, techs must evacuate an appliance component containing 10 pounds of CFC-500 to the following level before disposing of the appliance:
4 inches of Hg vacuum
What repairs are designated as major repairs under EPA regulations?
Replacement of the compressor, condenser, evaporator, or the auxillary heat transfer coils
System-dependent recovery equipment CANNOT be used when?
The appliance contains over 15 pounds of refrigerant
You are changing out the compressor of a system containing 40 pounds CFC-502. Your recycling equipment was manufactured AFTER 11/15/1993. In addition to isolating the compressor as much as possible, what else should you do?
Evacuate the isolated section of the system to 10 inches of vacuum hold. If system pressure does not rise, remove the compressor
Refrigerant has been recovered from an AC system and held in a refillable cylinder, in order to replace the condenser coil. The refrigerant can:
likely be charged back into the system
What else can recovered refrigerant contain?
Acids, moisture, oils
Recovering refrigerant from a system in vapor phase will minimize loss of:
Oil
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
In general, what is one routine maintenance task which must be performed on most refrigerant recycling machines?
Change oil and filter
After refrigerant liquid has been recovered from the appliance, any remaining vapor is:
Condensed by the recovery system
Refrigerant should be removed from the condenser outlet when:
The condenser is below the receiver
What should be done before transferring refrigerant to an empty cylinder?
Cylinder should be evacuated
During evacuation with large amounts of moisture it may be necessary to increase pressure to counteract freezing with gas such as:
Nitrogen
Liquid charging of a CFC-12 refrigeration system with risk of freezing is begun with vapor from a vacuum level to a pressure of approximately:
33 psig
Noncondensibles in a refrigerant system result in:
Higher discharge pressure (head pressure)
The component directly following the evaporator of a refrigeration system is the:
Accumulator
A moisture-indicating sight glass is useful for:
Checking the refrigerant’s moisture content
Dry nitrogen should be used to break the first vacuum when dehydrating by the double evacuation method. However, the cylinder must use:
A pressure regulator
What should be used to leak in an HFC-134a system for leak checking?
Pressurized nitrogen
A refrigerant oil that is hygroscopic:
Readily absorbs moisture
The term used to describe the fact that a refrigerant blend has a range of boiling or condensing points at a constant pressure is:
Temperature glide
When recovering refrigerant, what should be done to the High-pressure system before recovery?
System must be turned off and remain so, and as much as is possible, all solenoid valves should be open.
What side is the receiver on in a High-pressure system?
The high-side
High-pressure systems have a tendency to “load up” on moisture when opened. What must be done every time these systems are opened?
Change the filter-drier on the liquid line.
What are the 3 positions of a King Valve?
- Refrigerant flow through main line and service gauge. 2. Refrigerant flow through the main line only (backseated). 3. All ports closed.
What is the result of an undercharged system due to leaks?
Increase in superheat
What is one benefit each of recovering in the liquid phase and recovering in the vapor phase?
Liquid: faster recovery. Vapor: minimize loss of oil.
When using a recovery machine for a different refrigerant, what steps should be performed first?
- Oil must be drained and replaced with new oil for refrigerant. 2. All filters must be replaced. 3. Unit must be evacuated with another recovery machine or a “pump-out” cycle.
What should be done to the recovery tank during recovery?
Cool the tank.
What state must the appliance be in for recovery?
Turned off with service valves open, and as many solenoids open as possible.
