Trades Exam Prep is a free, daily podcast by OpenExamPrep covering the most in-demand skilled trades licensing and certification exams — including EPA 608 (HVAC refrigerant), FAA Part 107 (drone), Master Electrician, Plumber, General Contractor, ASE automotive, NATE, OSHA 10/30, Welder Certification, and more. Each 5-minute episode breaks down one exam topic with concrete examples, common exam traps, code references, and field-ready memory tricks to help you pass on your first attempt. No fluff, no filler — just the concepts you need to know, explained the way the exam tests them. This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP designation. He is passionate about opening access to high-quality exam preparation for everyone — from journeyman to master license, from apprentices to seasoned tradespeople. For free practice questions, AI-powered explanations, flashcards, and full study guides, visit https://open-exam-prep.com/ Subscribe and listen daily — your license is closer than you think.
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EPA 608 Prep 24, Very High-Pressure Refrigerants — R-744 and Subcritical CO2
Sunday, August 2, 2026 • Duration 03:18
This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams.
In this episode you will learn:
- R-744 (CO2) is the primary very-high-pressure refrigerant on the EPA 608 exam, with operating pressures far exceeding traditional systems.
- Servicing R-744 systems requires specialized equipment and gauges rated for pressures that can exceed 2000 psig.
- The critical temperature for R-744 is 87.8°F; above this point, the system operates in a transcritical state.
- Despite an A1 safety rating, R-744 is a dangerous asphyxiant, and leak detection in enclosed spaces is a critical safety concern.
- A Type II or Universal EPA 608 certification is mandatory to legally work on very-high-pressure R-744 systems.
For more free exam prep tools, practice questions, and AI-powered explanations, visit https://open-exam-prep.com/ or YouTube Channel: https://www.youtube.com/@Open-exam-prep
EPA 608 Prep 23, Type II — High-Pressure Refrigerants (R-22, R-410A, R-407C)
Saturday, August 1, 2026 • Duration 02:49
This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams.
In this episode you will learn:
- That Type II certification covers high-pressure (R-22, R-410A) and very-high-pressure (R-744 CO2) appliances.
- Why R-410A's higher operating pressures require dedicated gauges, hoses, and recovery equipment rated for that service.
- The proper procedure for charging zeotropic blends like R-407C as a liquid to prevent fractionation.
- The mandatory annual leak repair trigger rates for systems over 50 lbs: 10% for comfort cooling and 20% for commercial refrigeration.
- Key differences between the phased-out HCFC R-22 and modern HFC refrigerants like R-410A and R-407C.
For more free exam prep tools, practice questions, and AI-powered explanations, visit https://open-exam-prep.com/ or YouTube Channel: https://www.youtube.com/@Open-exam-prep
EPA 608 Prep 22, Small Appliance Refrigerants — R-134a, R-12, and Hydrocarbons
Friday, July 31, 2026 • Duration 02:59
This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams.
In this episode you will learn:
- The critical 1995 manufacturing year that distinguishes R-12 (CFC) systems from R-134a (HFC) systems on the exam.
- The environmental trade-offs between R-12 (high ODP), R-134a (high GWP), and R-600a (low GWP).
- Why the primary safety concern for modern hydrocarbon refrigerants like R-600a is their A3 flammability classification.
- The specific EPA charge limit for flammable refrigerants in domestic appliances is a tiny 57 grams.
- The number one rule for technicians is to always verify the refrigerant type on the appliance nameplate before service.
For more free exam prep tools, practice questions, and AI-powered explanations, visit https://open-exam-prep.com/ or YouTube Channel: https://www.youtube.com/@Open-exam-prep
This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams.
In this episode you will learn:
- Why heating a recovery cylinder creates a pressure differential to speed up refrigerant recovery.
- The only safe, EPA-approved heating methods, such as warm water baths and dedicated electric heat blankets.
- Why you must never use an open flame, like a torch, due to severe explosion risk and toxic gas formation.
- That refrigerant cylinders should never be heated above 125°F to avoid dangerous over-pressurization.
- How high heat contact with certain refrigerants can create deadly phosgene gas, a key exam topic.
For more free exam prep tools, practice questions, and AI-powered explanations, visit https://open-exam-prep.com/ or YouTube Channel: https://www.youtube.com/@Open-exam-prep
EPA 608 Prep 20, Recovery Cylinders and the 80 Percent Fill Rule
Wednesday, July 29, 2026 • Duration 02:31
This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams.
In this episode you will learn:
- Recovery cylinders must never be filled beyond 80% of their capacity by weight to allow for thermal expansion.
- Always use a scale and know the cylinder's tare weight (TW) and water capacity (WC) to calculate the maximum fill level.
- Overfilling can cause hydrostatic pressure, leading to a violent and dangerous cylinder rupture.
- It is a violation to mix different types of refrigerants in the same recovery cylinder.
- Recovery cylinders are gray with yellow tops and require hydrostatic testing every five years.
For more free exam prep tools, practice questions, and AI-powered explanations, visit https://open-exam-prep.com/ or YouTube Channel: https://www.youtube.com/@Open-exam-prep
EPA 608 Prep 19, Self-Contained Recovery on Small Appliances — the 90% Standard
Tuesday, July 28, 2026 • Duration 03:14
This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams.
In this episode you will learn:
- Self-contained recovery machines must be certified to recover 90% of the refrigerant from a small appliance if its compressor is operational.
- The 80% recovery standard applies only when a small appliance's compressor is inoperative.
- Do not confuse the machine's recovery efficiency (90%/80%) with the required field evacuation level of a 4-inch mercury vacuum before opening the system.
- Self-contained (active) recovery is much faster than passive recovery and is mandatory for systems with more than 15 lbs of refrigerant.
- A helpful mnemonic: "Active and Able gets you to Ninety," linking the more capable active machine to the higher 90% standard.
For more free exam prep tools, practice questions, and AI-powered explanations, visit https://open-exam-prep.com/ or YouTube Channel: https://www.youtube.com/@Open-exam-prep
EPA 608 Prep 18, System-Dependent Recovery on Small Appliances — the 80% Standard
Monday, July 27, 2026 • Duration 03:28
This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams.
In this episode you will learn:
- That system-dependent (passive) recovery is only permissible for small appliances with 5 pounds or less of refrigerant.
- The two critical recovery standards for small appliances: 90% for an operative compressor and 80% for an inoperative compressor.
- Specific techniques for recovering from a system with a non-functional compressor, such as gently heating the compressor (never with an open flame).
- How to differentiate between the 80% recovery efficiency rule and the separate 80% cylinder fill safety limit, a common exam trap.
- The mnemonic: A dead compressor can't give 90%, only a B-grade, 80%.
For more free exam prep tools, practice questions, and AI-powered explanations, visit https://open-exam-prep.com/ or YouTube Channel: https://www.youtube.com/@Open-exam-prep
EPA 608 Prep 17, Type I Open-Book Exam and the Passing Scores
Sunday, July 26, 2026 • Duration 02:43
This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams.
In this episode you will learn:
- That the EPA 608 Type I exam is the only section that can be administered in an open-book format.
- The different passing scores: 84% for the open-book Type I exam versus 72% for the closed-book Core, Type II, and Type III exams.
- That earning a Type I certification requires passing both the Core section and the Type I section.
- To avoid the common exam trap of assuming that Type II or Type III exams can also be taken open-book.
- That while an EPA 608 certification is valid for life and never expires, technicians must always follow current regulations.
For more free exam prep tools, practice questions, and AI-powered explanations, visit https://open-exam-prep.com/ or YouTube Channel: https://www.youtube.com/@Open-exam-prep
EPA 608 Prep 16, Type I — Small Appliances and the 5-Pound Limit
Saturday, July 25, 2026 • Duration 02:43
This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams.
In this episode you will learn:
- The precise three-part definition of a Type I small appliance: factory-manufactured, charged, and hermetically sealed with 5 pounds or less of refrigerant.
- Why motor vehicle air conditioners (MVACs) are covered by Section 609 and are a common exam trap for Type I questions.
- The specific refrigerant recovery requirements: 90% for a working compressor and 80% for an inoperative compressor.
- What "hermetically sealed" means in an exam context and why it necessitates the use of piercing valves for service.
- The unique rule allowing the Type I certification exam to be administered as an open-book test and the higher passing score required.
For more free exam prep tools, practice questions, and AI-powered explanations, visit https://open-exam-prep.com/ or YouTube Channel: https://www.youtube.com/@Open-exam-prep
EPA 608 Prep 15, Reclaimers and EPA-Authorized Recycling
Friday, July 24, 2026 • Duration 02:45
This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams.
In this episode you will learn:
- Only EPA-certified reclaimers can purify used refrigerant to AHRI 700 standards for resale to a new owner.
- Recycling is a less intensive cleaning process that allows refrigerant to be reused only in equipment belonging to the same owner.
- The key exam distinction is change of ownership: reclaiming allows for resale, while recycling does not.
- Following the 2020 ban on virgin R-22, reclaimed R-22 is the only legal supply for servicing older systems.
- Exam questions use scenarios to test whether you can differentiate between situations requiring reclamation versus recycling.
For more free exam prep tools, practice questions, and AI-powered explanations, visit https://open-exam-prep.com/ or YouTube Channel: https://www.youtube.com/@Open-exam-prep
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