List 6 desirable characteristics of a refrigerant
High latent heat
Non Toxic
Non Flammable
Non Corrosive
Chemically stable
Lubricant soluble
Name a Chlorine-free refrigerant
HFCs
What type of refrigerant are R-11 and R-12
Halocarbons
Name 3 types of refrigerant compounds and the element components of each
CFCs= chlorofluorocarbons
HCFCs= hydrochlorofluorocarbons
HFCs= hydrofluorocarbons
What is an azeotropic refrigerant
They combine and create a third refrigerant with its own individual characteristics
Which type of refrigerant is the most harmful to the stratospheric ozone
CFCs
Explain how blended refrigerants leak from a system
At different rates because of the individual refrigerant components have different vapor pressures
Explain how blended refrigerants are charged to a system
To charge by weight into the high side of the system as a liquid
Explain the term "temperature glide
Used to describe a blend of refrigerants that have a range of boiling points
Explain the term "azeotropic mixture
...
How do CFCs and bromine affect the ozone
Have caused a depletion of ozone in the stratosphere
Name the chemical found in the upper stratosphere that indicates ozone destruction
Chlorine monoxide
What does the ozone layer protect the earth from
Ultraviolet radiation from the sun
What evidence exists showing CFCs in the stratospheric ozone?
HFCs
How many ozone molecules can be destroyed by a single chlorine atom?
100,000
Name the refrigeration elements that cause ozone depletion
Chlorine and fluorine
Are volcanic eruptions considered contributors to the ozone depletion problem
Yes
What type of problem is stratospheric ozone depletion
global concern
what human health effects can result from increased exposure to UV radiation
increased problems in skin cancer and eye cataracts to a weakening of the immune system
list three effects ozone depletion can have on the evironment
affecting the growth and reproduction of photoplankton, reducing crop yields and marine life and increase ground level ozone.
how are CFCs affected by rainfall and/or water
CFCs are not washed out of spheres by rainfall and do NOT dissolve or break down into components that dissolve in water.
What refrigerants have the lowest ODP?
HFC-134a/CO2
explain the Montreal protocol agreement
a treaty among nations
what refrigerant compounds did the agreement control
CFCs
what chemicals are controlled by the Montreal protocol
Chlorofluorcarbons, halons and hydrochlorofluorocarbons.
what refrigerant have the highest ODP
CFC-12, CFC113
What is the base rfrigerant for the ODP numbering system
CFCs
Explain Ozone Depletion Potential (ODP)
is the relative amount of degradation to the ozone layer it can cause
Explain the requirements of the CAA
Phase out of CFC and HCFC production, no venting of CFC and HCFC after July 1,1992 EPA to set standards for
What precautions has the US taken to stop damage to the stratospheric ozone
They made the Clean air act
What requirements do individual state and local governments have regarding the CAA
Must conform to CAA regulations, but may invoke stricter regulations than required by EPA
What repercussions may a service technician be subjected to for violating the CAA
May loss certification, may be fined, may be required to appear in federal court
What constitutes a violation to the CAA
Releasing CFC/HCFC while repairing appliances
Falsifying of failing to keep required records
Failing to reach required evacuation levels before opening or disposing of appliances
Explain what fines a technician may be subjected to do violating the CAA
Notification of f a violation letter from the EPA that documents a violation and places it on file
What equipment is controlled under the EPA CAA regulation
All A/C&R equipment containing and/ or using CFC or HCFC refrigerants
What are the 3 main groups of refrigerant mineral oil
C-2, C-3, C-4
What is the synthetic oil most widely used with Terinary blends
Alkylbenzene
Define Hygroscopic
Refrigerant oil that has a high affinity for water
What type of refrigerant oil can be mixed with other oils
None
How can a vacuum pump be used to leak check a system
Failure of a system to hold a vaccine after evacuation indicates a leak may exist
Why vacuum pumps hoses be as short and as large in diameter
Will affect the time it takes to evacuate the system
What unit of measurement is used to measure deep vacuum
Microns
What documents should be reviewed before working with any chemicals
MSDS
Manifold high and low side gauges and hoses are colored coded what
High=red low=blue
What increments are used on low and high gauges on a manifold set
High=100 and low=10
How does the technician know what type of refrigerant is being used in a system
Nameplate
Explain the difference between a system dependent refrigerant recovery system and a self-contained refrigerant recovery system
System dependent recovery process small appliances may capture refrigerant in a non pressurized container while a self contained recovery device can cause excessive pressure on the high side
What type of recovery system is used only with less than 15 lbs of refrigerant
System dependent type (passive type)
Explain the difference in recovery procedures when using a system dependent recovery device when the compressor is operative and inoperative
Inoperative when it is necessary to access both the high and low side of the system for refrigerant recovery while operative run compressor on high side of the system
List the 2 types of self contained refrigerant recovery units used
Standard vacuum pump and Chill water pump
How often should you check your recovery unit for leaks
Daily basis
How large a chiller can currently available recovery units handle
2500 tons
What's a good way to minimize refrigerant release hoses are connected/disconnected
Quick coupling, self sealing hoses or ball valves
What type of fittings are required for all refrigerant recovery units
Low loss fittings
List those refrigerants that should not be recovered using current recovery devices
Ammonia, hydrogen and water
Explain the necessary documentation for refrigerant containers
Check refrigerant container meets DOT standards
Properly label the refrigerant container
Properly complete shipping paperwork
How do regulations differ for virgin and recovered refrigerant containers
Disposable cylinder should never be used to recover refrigerant
Disposable cylinders are used for virgin refrigerant only
For a technician to service a unit contains 50 lbs or more, what must be technician provide to the owner
Must provide owner with an invoice indicating the amount of refrigerant added to the appliance
What records are reclaimers required to keep
Names, addresses, and quantity of refrigerant sent to them for reclamation
Explain the shipping procedure for refrigerants
Check that the refrigerant containers meets DOT standards properly complete shipping paperwork
When are disposable cylinders acceptable
Never
How should a disposable cylinder scrapped
Assure that all refrigerant pressure in cylinder is at least 0 PSIG; render the cylinders useless by puncturing cylinder, recycle the metal
what information is on the label on the shoulder of a returnable/reusable container?
the test date will be stamped
describe the appearance of cylinders used in refrigerant recovery
shall have painted gray bodies
Explain the procedure for filing cylinders
Do not fill if the present date is more than 5 years past the test date on the container
define small appliances
sealed in a factory with5 lbs or less refrigerant
what requirements must be met by all recovery devices manufactured after November15, 1993 for small appliances
recovering 80% of the refrigerant or achieving a 4" HG whether or not the compressor is operating
Outline the EPA requirements effective November15, 1993 for type 1 system
less strict
what are low loss fittings
fittings that are used to connect the recovery device to an appliance and which can be manually closed
what is type 1 technician and what are the technicians responsibilities
identify refrigerant in the system
have a stable and known pressure and temp
after installing and operating a piercing valve, if the system pressure is "0" do not begin the recovery procedure
when installing any type of access fitting onto a sealed system
Describe the typical service aperture used for adding or removing refrigerant from a small appliance
a straight piece of tubing that is entered using a piercing access valve
why should you allow refrigerant inside a recovery cylinder to stabilize at room temperature
to check for air non condensable gases
why is an accurate pressure reading of refrigerant recovery cylinder necessary
the reading will indicate if excessive air or other non condensable are in the cylinder
what refrigerants are direct drop-ins for r-12 refrigerant
CFC/HCFC
what might a reclamation facility do if it received a tank of missed refrigerant
destroy it
what small appliance recovery process captures refrigerant in a non-pressurized container
passive recovery
when is it necessary to heat the compressor and strike it sharply and/or use a vacuum pump
when its inoperative
when can a standard vacuum pump be used as a recovery device
pressure tested
when can a standard vacuum pump be used as a recovery device
non-pressurized container
when a household refrigerator compressor does not run, why is it recommended that low and high side access valves be installed when recovering refrigerant from the system
the speed of recovery and to achieve require recovery efficiency
what should a storage cylinder of recovered R-22 at normal room temperature, in the absence of non -condensible, be pressurized to
132 PSIG
what conditions cause excessive pressure on the high side of a self-contained (active) recovery device
Air non condensible gases
what must system pressure be before beginning the recovery procedure after installing and opening a piercing access valve
0
why shouldn't solder less type piercing valves remain installed on refrigeration systems after completion of repairs
they tend to leak overtime
what has likely occured when a pungent odor is detected during a sealed system recovery and/or repair
acid
on a sealed system, with an operating compressor that has a completely restricted capillary tube, how many access valves are needed to evacuate the system
2
what should the nitrogen tank always be equipped with when nitrogen is being used in the repair of a refrigeration system
regulator
what does R-12 and R-22 decompose to at high temperatures
phosgene gas/hydrochloric and hydrofluoric acids
List the critical procedures for using recovery cylinders and equipment with Schrader valves
Cap the Schrader ports to prevent accidental depression of the valve core; replace damaged Schrader valve core to prevent leakage; inspect the Schrader valve core bends.
what EPA requirements govern leak repair
when the leak rate exceeds 35% of the charge
Explain the procedure for recovering/recycling refrigeration in Type2 systems
you must connect one hose to the liquid line
After refrigerant liquid has been recovered from the appliance, any remaining vapor is condensed (recovered) by the recovery unit
what EPA requirements govern recovery/repair of refrigerant in type2 systems
when the leak rate exceeds 15% of the charge per year
For equipment room, what does ASHRAE STD 15 require for A-1 refrigerants
Monitor oxygen levels
how is hydrostatic tube test kit used
a hydrostatic tube test kit will determine if there is a leak in a tube
what is the maximum test pressure for leak testing a low pressure centrifugal unit with nitrogen
10 PSIG
what is an effective method for leak checking a charged low pressure refrigeration unit
raising the system pressure by heating with circulating hot water or heating blankets
on a CFC-11 chiller, what can be accomplished to reduce refrigerant loss from the purge unit
leak test and repair
where would you place a leak detector probe if you were checking for leaks in the water box and the water was removed
place leak detection probe through a drain valve
where would moisture most likely enter a low pressure chiller
enters the refrigerant system on low pressure chillers through air leaks
what are EPA leak rate requirements for an appliance containing more than 50lbs of refrigerant
less than 15% of the total charge in a year
what are the EPA leak rate requirements for commercial and industrial refrigeration equipment
35%
what is the high pressure cut-out set for when evacuating refrigerant from a low pressure chiller
10 PSIG