Refers/EPA Midterm Flashcards
The synthetic lubricant presently used with ternary blends containing HCFCs is:
Alkylbenzene
Which is NOT true of recycling and recovery equipment manufactured after November 15, 1993?
It must have an oil separator.
Oil separators are NOT required.
Charging liquid refrigerant into a refrigeration system under 29 inches Hg vacuum can cause:
System water to freeze
R-22 is an ______ refrigerant
HCFC
R-12 is a _____ refrigerant.
CFC
R-123 is a ___ ______ refrigerant under EPA regulations for recycling refrigerant.
Low pressure
When working with solvents, chemicals, or refrigerants, a technician should review the:
Material safety data sheets
Under what code group of ASHRAE Standard 34 does R-123 fall?
B1
When leak testing a low-pressure centrifugal with nitrogen, what is the maximum test pressure?
10 psig
What else is NOT true of refrigerant recycling and recovery equipment manufactured after November 15, 1993?
It must be able to handle more than one refrigerant.
Refrigerants should NEVER be mixed!
Identify the pressure corresponding to 32°F for R-123
20 inches Hg vacuum
Each chlorine atom in the stratosphere can destroy ______ ozone molecules
100,000
How do you determine when enough vapor has entered the refrigeration system before you charge refrigerant liquid?
Refrigerant saturation temperature increases to 36°F
Recovery equipment that relies upon the Compressor in the appliance and/or the pressure of the refrigerant in the appliance would be considered:
System-dependent
Excessive running of a purge system on a low-pressure chiller generally indicates what condition?
The system is leaking
It will be illegal to vent substitutes for CFCs and HCFCs after:
November 1995
The oils that will be employed with most of the HFC-134a refrigeration applications are:
Esters
Liquid charging of an R-12 refrigeration system with risk of freezing is begun with vapor from a vacuum level to a pressure of approximately:
33 psig
The system dependent (passive) recovery process:
Recovers refrigerant in a non-pressurized container
Leak testing a low-pressure refrigeration system with the nitrogen in excess of 10 psig could cause what to fail?
Rupture disc
R-11 at 14.7 psia will boil at approximately:
74.5°F
When a system trace gas becomes absolutely necessary, which of the available refrigerants should be used to identify a leak?
HCFC-22
High head pressure could be an indication of:
non-condensables collecting in the condenser
Frost build up on the suction side of the compressor can
indicate __________.
too little superheat in refrigerant vapor
Which condition(s) can cause excessive pressure
conditions on the high side of a self-contained (active)
recovery device?
when the recovery tank inlet valve has not been
opened, and …
when there is excessive air in the recovery tank
When using recovery and recycling equipment
manufactured BEFORE November 15, 1993, technicians
must evacuate an appliance containing 10 pounds of
CFC-500 to what level before disposing of the
appliance?
4 inches of Hg vacuum.
Recovery equipment used during maintenance, service or repair of small appliances must be certified by an EPA-
approved laboratory if manufactured after:
November 15, 1993.
EPA regulations include which of the following in the
definition of a “small appliance”?
products manufactured, charged and hermetically
sealed in a factory, AND
products having 5 pounds or less of refrigerant
What should be done to reduce refrigerant loss from a
purge unit on a CFC-11 chiller?
leak test and repair the chiller
A heater used on a recovery vessel aids in the faster
transfer of ______ from the chiller during recovery.
vapor
On a sealed system with an operating compressor that
has a completely restricted capillary tube, how many
access valves are needed to evacuate the refrigerant?
Only one access valve, on the high of the system.
Removal of the refrigerant charge from a system can be
conducted more quickly by:
packing the recovery vessel in ice.
The state of the refrigerant entering the compressor of a
refrigeration system is:
low pressure vapor.
Which compounds have the highest ozone depletion
potential (ODP) ?
CFCs
A rupture disc on a recovery vessel for low pressure
refrigerants relieves at:
15 psig
Where does refrigerant go after it leaves the purge unit of
a low pressure centrifugal system?
the evaporator
All recovery devices manufactured before November 15,
1993 for use with small appliances must meet which of
the following requirements?
capable of recovering 80% of the refrigerant whether or not the compressor is operating or achieving a 4 inch vacuum under conditions of ARI 740
To remove ice from sight glasses or viewing glasses use:
an alcohol spray
EPA regulations require that all appliances containing
more than 50 pounds of refrigerant (except for
commercial and industrial process refrigeration) be
repaired when the leak rate exceeds ___ percent of the
charge per year.
15
When using recovery or recycling equipment
manufactured BEFORE November 15, 1993, technicians
must evacuate low-pressure appliances to the following
level before making a major repair:
25 inches of Hg vacuum.
What should be done before transferring refrigerant to an
empty cylinder?
The cylinder should be evacuated.
EPA regulations require that leaking commercial and
industrial process refrigeration be repaired when the leak
rate exceeds ____ percent of the charge per year.
35
You are changing out the compressor of a system containing 40 pounds R-502. Your recycling equipment was manufactured AFTER November 15, 1993. In addition to isolating the compressor as much as possible, which of the following procedures should you follow?
Evacuate the isolated section of the system to 10 inches of
vacuum and hold. lf system pressure does not rise, remove the compressor.
What is the typical design burst pressure for a rupture
disk on a low pressure centrifugal air-conditioning
system?
15 psi
When using recovery and recycling equipment
manufactured AFTER November 15, 1993, technicians
must evacuate low-pressure appliances to the following
level before disposing of the appliance:
25 mm of Hg absolute
When recharging a refrigeration system with R-11. What vapor pressure is necessary in the shells before charging with liquid?
16.9” Hg vacuum
Noncondensables in a refrigeration system result in:
higher discharge pressure
A standard vacuum pump designed specifically for
evacuation and dehydration can:
never be used as a recovery device in combination with a pressurized container.
A storage cylinder of recovered R-22 at normal room
temperature (about 75 degrees F), in the absence of
non-condensables, will be pressurized to:
130 psig (see chart)
Which of the following leak detection methods is
considered to be the most effective for locating the
general area of a small leak?
electronic or ultrasonic tester
After installing and opening a piercing access valve, if
the system pressure is _________ do not begin the
recovery procedure.
o psig
Which of the following is not an approved technique of
system cleanup after a burnout?
flushing with liquid refrigerant to clean field tubing.
Equipment manufactured after November 15,1993 which
is used to recover refrigerant from small appliances for
the purpose of disposal must meet what standard?
Recover 80% with an inoperative compressor, AND 90% with an operative compressor.
System-dependent recovery equipment CANNOT be
used when:
the appliance contains over 15 pounds of refrigerant.
CFCs will no longer be manufactured or imported into the U.S. after:
1995
When you check system pressures to determine the
performance of a refrigeration system, it’s always a good
idea to:
use equipment such as hand valves or self-sealing hoses to minimize any release.
Recycling or recovery equipment using hermetic
compressors has the potential to overheat when drawing
deep vacuums because:
the motor relies on the flow of refrigerant through the compressor for cooling.
The state of the refrigerant leaving the receiver of a
refrigeration system is:
high pressure liquid
The piping connection to the vacuum pump should be:
as short in length and as large in diameter as possible.
When using recovery and recycling equipment
manufactured AFTER November 15, 1993, technicians
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
NOT 4 INCHES!! As with recovery equipment manufactured BEFORE November 15, 1993.
When servicing a small appliance for leak repair:
it is not mandatory to repair the leak but do so whenever possible
The smallest container in which refrigerants may be sold to Section 608 certified technicians is:
20 pounds
To speed the recovery process and ensure that all refrigerant has been removed from a frost-free refrigerator:
turn on the defrost heater to vaporize any trapped liquid
An oil sample should be taken for which of the following reasons?
the unit has had a compressor burnout
At high temperatures (i.e. open flames, flowing metal surfaces, etc.) R-12 and R-22 can decompose to form:
phosgene gas
A nitrogen tank should always be equipped with a:
regulator
R-11 at 18.1 in Hg vacuum has a saturation temperature of:
32*F
Air in a low pressure system is indicated by:
high head pressure
On a centrifugal system, the purge unit takes its suction from the:
top of the condenser
Where does refrigerant go after it leaves the purge unit of a low pressure centrifugal system?
the evaporator
Under EPA’s regulations, which of the following methods can be used to pressurize an R-11 or R-123 system for the purpose of opening the system for a non-major repair?
warming the refrigerant
R-123 at __ inches of Hg vacuum corresponds to 32*F
20 in
A deep vacuum is usually measured in:
MICRONS
Where would you place a leak detector probe to check gas leaks into the water box with water removed?
through a drain valve (refrigerant would settle at the bottom of the water box)
Refrigerant is added to a centrifugal machine through the:
evaporator charging valve
When removing oil from a low pressure system, the temperature should be 130*F because:
less refrigerant will be contained in the oil at the higher temperature
When using recovery or recycling equipment
manufactured BEFORE November 15, 1993, technicians
must evacuate low-pressure appliances to what
level before making a major repair?
What about AFTER November 15, 1993?
25 inches of Hg vacuum BEFORE Nov 15, 1993.
25mm of Hg absolute AFTER Nov 15, 1993.
With a low-pressure chiller, what must you do after recovering the liquid refrigerant?
recover the vapor refrigerant
Before using a recovery unit to remove a charge, what steps should be taken?
-Check service valve positions
-Check recovery unit oil level
-Evacuate recovery unit/receiver
(All of the above)
