The hands-on half of EPA Section 608 certification — recovery, evacuation, and service practices for Type I small appliances, Type II high-pressure systems, and Type III low-pressure chillers. Master self-contained vs system-dependent recovery, the required recovery and evacuation levels for each appliance class, the 80% cylinder fill limit, pressure–temperature relationships and spotting non-condensables, deep-vacuum dehydration in microns, safe leak testing with regulated nitrogen (never oxygen or compressed air), low-pressure purge units and the 10 psig test limit, and retrofit fundamentals. Every question teaches the practice and diagnoses the dangerous or exam-classic error. Authored from the public EPA regulations (40 CFR Part 82) using original questions — never real exam items. Keentune is independent study practice, not affiliated with the EPA or any certifying organization, and does not guarantee a pass. Educational only — always follow current regulations and equipment manuals on the job.