Roughly what reading equals the 25 mm Hg absolute level in Table 1?

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

A technician's micron gauge is used to confirm the evacuation of an R-11 chiller. Roughly what reading equals the 25 mm Hg absolute level in Table 1?

• A500 microns
• B25,000 micronsCorrect answer
• C2,500 microns
• D250,000 microns

Why “25,000 microns” is correct

A micron is one-thousandth of a millimetre of mercury, measured from a perfect vacuum. 25 mm Hg absolute is therefore 25,000 microns, the level a low-pressure appliance must reach before it is opened or disposed of.

Source: 40 CFR 82.156(a), Table 1; EPA: Test Topics

Why the other answers are wrong

• 500 microns — 500 microns is a common dehydration target and is far deeper than the Table 1 recovery level.
• 2,500 microns — This is off by a factor of ten; 1 mm Hg equals 1,000 microns.
• 250,000 microns — This is off by a factor of ten in the other direction.

Practice more of this

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