What does this most likely mean?

Recovery requirements · EPA 608 Type III. The correct answer, and the reasoning behind it.

Evacuation levels for low-pressure appliances, and major versus non-major repairs.

The question

After pulling an R-11 chiller down to 25 mm Hg absolute, a technician valves off the recovery unit and waits. Within a few minutes the pressure in the chiller starts to rise. What does this most likely mean?

• ALiquid refrigerant is still boiling off in the chiller or its oilCorrect answer
• BThe recovery unit has tripped its high-pressure cut-out
• CThe purge unit is feeding air back into the shell through its vent line
• DThe reading is normal and the chiller can be opened

Why “Liquid refrigerant is still boiling off in the chiller or its oil” is correct

EPA's test topics stress waiting a few minutes after reaching the required vacuum. If the pressure climbs, liquid refrigerant is still in the system or dissolved in the oil and is flashing to vapor. Recovery must continue until the level holds.

Source: EPA: Test Topics; 40 CFR 82.156(a)

Why the other answers are wrong

• The recovery unit has tripped its high-pressure cut-out — The recovery unit is valved off, so its cut-out would not change the chiller pressure.
• The purge unit is feeding air back into the shell through its vent line — The purge removes noncondensables; it does not add air to the shell.
• The reading is normal and the chiller can be opened — A rising pressure shows the evacuation is not finished and the chiller is not ready to open.

Practice more of this

More EPA 608 Type III practice questions, or see every EPA 608 practice test.