Why do HCFCs do less damage to the ozone layer than CFCs?
The hydrogen in the molecule lets it break down lower in the atmosphere
The fluorine in the molecule cancels out the effect of the chlorine atoms
HCFC molecules are too heavy to rise above the troposphere
HCFC molecules contain bromine in place of the chlorine
Show the answer
A. The hydrogen in the molecule lets it break down lower in the atmosphere
Hydrogen makes an HCFC molecule less stable, so most of it breaks down before reaching the stratosphere and less chlorine arrives there. Fluorine does not neutralize chlorine, and molecular weight does not keep refrigerants out of the stratosphere.
Reference: EPA Section 608 Core
A technician who holds only Type I certification is asked to recover the refrigerant from a 3-ton residential split system. The technician
may do the work, because the charge is under 15 lb
may do the work if a self-contained machine is used
may not do the work, because it requires Type II certification
may not do the work, because it requires Type III certification
Show the answer
C. may not do the work, because it requires Type II certification
A split system is not a small appliance, so Type I does not cover it; R-22 and R-410A split systems are high-pressure appliances under Type II. The size of the charge alone does not make something a small appliance.
Reference: 40 CFR 82.161
Type II certification covers which equipment?
Low-pressure centrifugal chillers and the purge units that are fitted to them
Factory-sealed appliances that hold five pounds of refrigerant or less
Motor vehicle air conditioners and the MVAC-like systems on farm equipment
Medium-, high- and very high-pressure appliances other than small appliances and MVACs
Show the answer
D. Medium-, high- and very high-pressure appliances other than small appliances and MVACs
Type II covers medium-, high- and very high-pressure appliances, except small appliances (Type I) and motor vehicle systems (Section 609). Low-pressure chillers fall under Type III.
Reference: 40 CFR 82.161
R-123 belongs to which group of refrigerants?
HCFC
CFC
HFC
HFO
Show the answer
A. HCFC
R-123 is an HCFC that replaced CFC-11 in low-pressure chillers. Because it still contains chlorine it has a small ODP and is covered by the Section 608 leak repair rule.
Reference: Clean Air Act Title VI (Class II substances)
Chlorine from CFCs reaches the stratosphere, while most chlorine from natural sources such as sea spray does not. What is the main reason?
CFCs are lighter than air, so they rise much faster than natural chlorine does
CFCs are released at high altitude, well above the clouds and the rain
CFCs are stable and do not dissolve in water, so rain does not wash them out
CFCs carry far more chlorine per molecule than any natural source does
Show the answer
C. CFCs are stable and do not dissolve in water, so rain does not wash them out
CFCs do not break down or dissolve in water in the lower atmosphere, so they survive long enough to drift up to the stratosphere. Natural chlorine compounds are water soluble and are rained out. CFCs are actually heavier than air; mixing by winds carries them up.