The work:Replacement, start-up, and check of an existing air conditioning system condensing unit.
The apprentice:Allen Charles Edwards (ACE) — first-year mechanic.
The technician:N. Arthur Thomas Egan (NATE) — 15-year hvacr veteran.

As the cooling season approaches, Nate and Ace are switching gears, performing cooling start-ups and changing out components. While on their first call, a condensing unit replacement, the discussion turns to the required refrigerant handling techniques and proper system maintenance.

NATE: “Ace, what level of refrigerant certification do you have?”

ACE: “Level four.”

NATE: “Level four? Never heard of it.”

ACE: “In school, we took the Section 608 Refrigerant Handling Exam, and I passed all four parts. Does that mean I have a level four certification?”


NATE: “Not really, Ace. Passing all four sections of the test means you have aUniversalCertification. First you had to pass the Core section of the exam. Then, upon passing the other sections of the exam, you receive your certification in that type. And since we’re replacing a 36,000 Btu HCFC-22 split-system condensing unit today, what is the required evacuation level that we must have for the proper system recovery?”

a) 0 microns
b) 250 to 500 microns
c) 0 in. Hg
d) 28 to 29 in. Hg


NATE: “OK, Ace. Figure this out: What is the usual acceptable level of evacuation for a system being installed or replaced?”

a) 0 microns
b) 250 to 500 microns
c) 0 in. Hg
d) 28 to 29 in. Hg


NATE: “Ace, what would a compound gauge reading of 0 in. of Hg be in microns?”

a) Approximately 0 microns
b) Approximately 250,000 microns
c) Approximately 500,000 microns
d) Approximately 750,000 microns

NATE: “So Ace, tell me, why is there such a big difference between the allowable reading for recovering refrigerant and the acceptable level of evacuation?”

ACE: “When we’re recovering refrigerant to protect the environment, all the refrigerant must be removed — and 0 in. Hg is the acceptable level as required by the law. But when we set up a system, we have to make sure we remove all the noncondensable gases, so a reading of between 250 to 500 microns will be enough to have removed any moisture in the system.”

NATE: “Do you think the practice of just recovering the refrigerant is sufficient for good refrigerant system practice?”

ACE: “Removing the refrigerant to 0 in. Hg is good for the environment, but not for clean system operation.”

NATE: “So does the mandatory refrigerant handling law cover all the requirements for being a good technician in the industry?”

ACE: “No. It doesn’t cover anything about electricity, furnaces, control systems, and the like. It’s a great law for protecting the environment from venting the refrigerants, but I think you need to know a lot more for technician excellence.”

NATE: “Right you are!”

Answers: 1) c; 2) b; 3) d

Please remember, no question appearing in these articles is on a NATE Exam. These questions and dialogue are my creation alone. The NATE Technical Committee does not review the article content — and the committee has the final decision for the use of a question on the tests.

Interpretation of codes, regulations, and standards comes from my experience as a technician and a contractor. Different jurisdictions have varying interpretations. The particular area in which a job is being done will dictate which viewpoint is to be properly used.

I learn a lot from your commentary and try to incorporate information into the next article, so please continue to comment.

Patrick L. Murphy

Murphy is director of technical development, North American Technician Excellence (NATE). If you have any further questions or comments on this Fundamentals quiz, contact Murphy at (e-mail).

Publication date: 05/27/2002