A residential split system holding eight pounds of R-22 must be opened to change the compressor, and the recovery machine on the truck carries a 2015 build date. What vacuum level does the appliance have to reach before the lines are cut?
Correct Answer
A) Zero inches of mercury vacuum
The evacuation table gives R-22 appliances holding less than two hundred pounds their own line, and that line reads zero inches of mercury vacuum in both equipment-age columns. Zero inches of vacuum means the system has been brought down to atmospheric pressure, so a residential split with an eight pound charge is finished once the gauge stops showing positive pressure and holds there. The deeper figures on the table belong to larger charges and to the other refrigerant families.
Why This Is the Correct Answer
R-22 is called out by name in the evacuation table, and appliances of that kind whose normal charge is under two hundred pounds carry a required level of zero inches of mercury vacuum. That is atmospheric pressure. The number does not change with the age of the recovery equipment, so an eight pound residential split is at the required level as soon as the pressure is down to zero and stays there.
Why the Other Options Are Wrong
Option B: Four inches of mercury vacuum
Four inches of mercury vacuum is the older-equipment figure for larger charges and for the other high-pressure refrigerants, not for a small R-22 system.
Option C: Ten inches of mercury vacuum
Ten inches of mercury vacuum comes from the rows covering two hundred pounds or more of R-22, and from smaller charges of the other high-pressure refrigerants.
Option D: Twenty-five inches of mercury vacuum
Twenty-five inches of mercury vacuum is a low-pressure chiller figure. Applying a Type III number to a residential split is a common cross-section mistake.
Memory Technique
Small R-22 job, small number. Zero pounds of pressure left is zero inches of vacuum needed.
Reference Hint
R-22, charge under two hundred pounds: zero inches of mercury vacuum, meaning atmospheric pressure.
More epa-608-type-2 Questions
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