About Sight Glass
Sight Glass is an independent, free study site for the EPA Section 608 technician exam, made by the people who build the iPhone and iPad practice app that its Get the app buttons open.
Why the name
A sight glass is the small window in a liquid line that shows whether the refrigerant passing it is a solid column of liquid or carrying bubbles. You look before you add anything. This site does the same for your prep: it shows where your grasp of the rules is clear and where it still bubbles, before the test does.
What Sight Glass is, and what it isn't
- A study site
- Practice questions with a note on each option, a timed mock and topic guides for the 608 exam. No account, no sign-up.
- Not a certifying program
- It doesn't give the test, issue or replace wallet cards, or confirm anyone's certification. Those belong to the program you test with; EPA 608 certification lookup and replacing a lost EPA 608 card explain where to go.
- Not connected to EPA
- Sight Glass is not affiliated with or endorsed by the U.S. Environmental Protection Agency or any certifying organization. EPA states that it does not review or approve any training or prep material (EPA list of certification programs, checked October 7, 2026).
- Not legal advice
- Rule citations are here so you can check an exam answer. A compliance question about your own business belongs with the rule text or a qualified advisor.
How a fact gets onto a page
Primary source first
Exam rules come from 40 CFR Part 82, Subpart F on eCFR and from EPA's Section 608 pages. Prices and program details come from each program's own page.
Dated where it appears
A figure carries its source and the date it was checked, because programs reprice and EPA edits its pages. Rule text here is cited as of October 5, 2026; web pages were checked on October 7, 2026.
Left out when it can't be traced
Pass rates, prices that only appear on third-party copies, and time limits presented as EPA rules stay off the site. Figures that come from common practice and not from the rule text are labeled that way where they appear.
Attributed when secondhand
News that hasn't reached an EPA page yet, such as the change of question bank, is published with the name of whoever said it and the date.
How the questions are checked
The questions come from the app's own set of practice questions and are written to EPA's test topics (EPA test topics, checked October 7, 2026). Before one is published here, a second reviewer answers it blind, seeing only the stem and the options, and that answer is compared with the key.
Then each option gets its own note: why the key holds up, and what's wrong with each of the others. A blind answer that disagrees with the key, a question with two defensible answers, or a note that can't be written cleanly sends the question back to be fixed or replaced.
Think a key is wrong anyway? The Sight Glass contact page lists what to send so it can be checked quickly.