Core
Which refrigerant is a CFC?
a. R-134A
b. R-123
c. R-22
d. R-12
a. R-134A
What is the EPA definition of a small appliance?
Manufactured, charged and hermetically sealed in a factory and contains five pounds or less of refrigerant
Before charging a new system with refrigerant, what should be done?
Pressurize with nitrogen (classified as an inert gas) and leak checked.
Where do leaks commonly occur in low pressure systems?
Gaskets or fittings
As of what date did it become unlawful to release Class 1 and Class II refrigerants to the atmosphere?
July 1, 1992
What is ODP?
Ozone Depletion Potential
Should regulations of the clean air act )CCA) change after a technician is certified:
It will be the technicians responsibility to learn and comply with future changes in the law.
What are the leak repair requirements for comfort cooling appliances and commercial Appliances containing 50 lbs. or more of refrigerant?
Must be repaired if leak rate exceeds 15% in comfort cooling appliances.
Must be repaired if leak rate exceeds 35% in all commercial and industrial process refrigeration
When should a low pressure system be leak checked according to ASHRAE guideline 3-1996?
When the system rises from 1 mm Hg to a level above 2.5 mm Hg during vacuum testing
When was the CFC phase out date?
December 31, 1995
What characteristics make it easy for CFCs to reach the stratosphere and how do they get there?
CFCs will not dissolve in water or break down into compounds that dissolve in water. Wind moves them into the Stratosphere
System dependant (passive) refrigerant recovery of small applianves:
Do not require an operating compressor.
Requires 80% of the refrigerant to be recovered.
Recovers refrigerant in a non pressurized container.
What is the purpose of the filter drier and when should it be changed?
To remove moisture from the refrigerant, replace on a routine basis or anytime a system is opened
What does a purge unit do and what is a high efficiency purge unit?
Removes the air from the system. High efficiency purge system will expel very little refrigerant
For small appliance use, the recovery equipment manufactured after November 15, 1993 must be capable of recovering:
80% of the refrigerant when the compressor is not running or achieve a 4 inch vacuum under ARI 740-1993.
90% of refrigerant when the compressor is operating or achieve a 4 inch vacuum under ARI 740-1993.
What chemicals does the Montreal Protocol control?
chlorofluorocarbons (CFCs)
halons
carbon tetrachloride
methyl chloroform
Recovery equipment manufactured after November 15, 1993 must meet what standards if using a compressor?
Be capable of recovering 90% of the refrigerant with the compressor operating or achieve a 4 inch vacuum under conditions of ARI 740.
Foaming at start-up may be found in what component? What does this mean?
Refrigerant in the compressor oil will cause oil foaming. Prevent refrigerant migration with a crankcase heater
How does a centrifugal compressor purge unit work?
Takes its suction from the top of the condenser, removes the air from the system, and returns the refrigerant to the evaporator
The sale of Class I and Class II refrigerants will be restricted to technicians certified by an EPA approved program after:
November 14, 1994
Who is responsible for removing refrigerants from a system that is being disposed of?
Final person in the disposal chain
What is the difference between a self-contained recovery tank and a system-dependent recovery tank?
Self-contained (active) recovery equipment uses its own power to recover the refrigerant from systems and is capable of reaching the required recovery rates with or without the compressor operating
A system dependant (passive) recovery tank does not have its owncompressor.
Exceptions to the required evacuation levels for recovery equipment that require an appliance be evacuated to only 0 psig apply to appliances that.
Are filled with water or substances that would damage the recovery equipment
At what point in the system should you charge a low pressure system and what should you start the charge with?
Charge through the evaporator charging valve as this is the lowest point on a low pressure system. First charge the system with vapor
What are the required levels of evacuation for low pressure systems for equipment manufactured before 11/15/1993 and/or after 11/15/1993?
25” Hg for equipment manufactured before November 15, 1993.
25 mm Hg absolute for equipment manufactured after November 15, 1993.