EPA 608 Type II & III Practice Tests

EPA 608 Type II (high-pressure) and Type III (low-pressure) certification practice — commonly studied together.

23 tests · 575 questions · Free · No signup · EPA Section 608
Based on the National Electrical Code (NFPA 70) — NEC 2020, 2023 & 2026 editions covered.  ·  Last reviewed Jun 2026

EPA 608 Type II and Type III: High-Pressure and Low-Pressure Certification Explained

The EPA Section 608 certification has four parts: Core, Type I, Type II, and Type III. Type II and Type III are almost always studied together, and there's a practical reason for that. Type II covers the high-pressure equipment that most working HVAC/R technicians deal with every day — split systems, heat pumps, rooftop units, and light commercial refrigeration. Type III covers a narrower, more specialized world: low-pressure centrifugal chillers found in hospitals, malls, universities, and large commercial buildings. The two sections share a lot of underlying refrigeration theory — pressure/temperature relationships, recovery requirements, leak standards — but they diverge sharply on one core concept: whether the refrigerant in the system is above or below atmospheric pressure. Understanding that single difference is the key to passing both exams, and it's also why exam writers love to test candidates on which rule applies to which system.

If you're pursuing Universal certification (Core + Type I + Type II + Type III), you have to pass all four sections, but you don't have to take them in one sitting or in a fixed order — Core must be passed at some point, but many test providers let you attempt Type I, II, and III in any sequence, including in the same test session. Most technicians study Type II first because it maps directly onto the equipment they already touch in the field, then move into Type III once the high/low pressure distinction is solid. This guide follows that order: a deep look at Type II, then Type III, then a side-by-side comparison so the differences stay clear going into the exam.

Type II Certification: High-Pressure Appliances

Type II certification covers appliances classified as high-pressure or very-high-pressure. In practice, this is the equipment category most technicians spend their careers working on.

What Equipment Requires Type II

  • Residential split systems — the condenser/evaporator setups found in most homes, typically charged with R-410A or, increasingly, R-32 or R-454B.
  • Heat pumps — both split and packaged configurations, residential and light commercial.
  • Rooftop package units — self-contained systems common on commercial buildings, combining condenser, compressor, and air handling in one cabinet.
  • Light commercial refrigeration — walk-in coolers, reach-in cases, and similar equipment using high-pressure refrigerants.
  • Window units and PTACs in some cases, depending on refrigerant and system design.

The defining feature of a Type II system is that it operates above atmospheric pressure during normal operation. When a leak develops, refrigerant pushes out of the system into the surrounding air. That outward pressure differential is the reason recovery procedures, evacuation levels, and leak-detection methods for Type II look the way they do — everything is designed around containing pressurized refrigerant and pulling it down to a safe, low vacuum before the system is opened, serviced, or scrapped.

The exam materials actually split this category into two sub-classes: high-pressure appliances (most common refrigerants used in residential and light commercial equipment) and very-high-pressure appliances (systems using refrigerants with notably higher operating pressures at a given temperature than typical high-pressure refrigerants). For exam purposes, both fall under the umbrella of Type II certification and are covered by the same recovery, evacuation, and leak-detection rules — you don't need a separate credential for very-high-pressure equipment, but you should recognize that the category exists and understand that it's grouped with, not separate from, standard high-pressure appliances.

Evacuation and Vacuum Level Requirements

Before you can open a Type II system to the atmosphere for major repair, or before you dispose of one, EPA regulations require you to evacuate it to a specified vacuum level using recovery equipment. The required level depends on how much refrigerant the system holds, and it assumes you're using recovery equipment manufactured after November 15, 1993 (older equipment has different, generally less demanding requirements, but virtually everything in service today falls under the post-1993 standard).

System Refrigerant ChargeRequired Vacuum Level
Less than 200 lbs of refrigerant10 inches of mercury (Hg)
200 lbs or more of refrigerant15 inches of mercury (Hg)

Exam tip: Notice the relationship — the larger the charge, the deeper the vacuum required (15" Hg is a deeper vacuum than 10" Hg; both are measured as vacuum below atmospheric pressure, so a bigger number means less refrigerant remains in the system). Small systems get a shallower requirement because there's simply less refrigerant that could remain behind and eventually leak to atmosphere.

These numbers apply specifically to Type II (high-pressure) appliances. Type III uses a completely different framework because low-pressure chillers don't hold refrigerant under positive pressure in the same way — more on that below. Mixing up the Type II vacuum table with Type III's requirements is one of the most common ways candidates lose points on the combined exam material.

Recovery Methods for Type II Systems

Type II technicians need to know three recovery approaches and, more importantly, when each one is appropriate.

  • Vapor recovery — the recovery machine pulls refrigerant vapor out of the system and condenses it into a recovery cylinder. This is the standard, most common method and works well for small to moderate refrigerant charges, especially when most of the charge is already in vapor form or the system charge is small enough that recovery time isn't a major concern.
  • Liquid recovery — refrigerant is pulled from the system in liquid form rather than vapor. Because liquid is much denser than vapor, liquid recovery moves refrigerant out of a system considerably faster than vapor recovery, which matters on systems with a large charge.
  • Push-pull recovery — used specifically for systems with large liquid charges (the EPA materials generally reference systems with roughly 50 lbs of refrigerant or more as the point where push-pull becomes the practical choice). Instead of relying solely on the recovery machine's own pump to move refrigerant, push-pull uses the system's own pressure differential to help push liquid refrigerant out of the appliance and into the recovery cylinder, while the recovery machine pulls vapor off the top of the cylinder to keep the pressure differential going. This dramatically speeds up recovery on large systems compared to standard liquid or vapor recovery alone.

Exam tip: The exam loves to test push-pull scenario recognition. The signal phrase to watch for is "large liquid charge" or "large system." If a question describes recovering refrigerant from a big commercial system with a substantial liquid charge, push-pull is very likely the intended answer — not plain vapor recovery.

Leak Detection Methods for Type II

Because Type II systems run at positive pressure, a leak pushes refrigerant outward, which makes several detection methods practical:

  • Electronic leak detectors — handheld sniffers that detect refrigerant molecules in the air near a suspected leak point. Sensitive, portable, and the most commonly used method in the field.
  • Ultraviolet (UV) dye — a fluorescent dye is added to the system's oil or refrigerant charge; over time it migrates to leak points and shows up under a UV/black light, revealing the leak location visually — useful for slow or intermittent leaks that are hard to catch with a sniffer alone.
  • Soap bubble solution — a simple, low-cost method where soapy solution is applied to fittings, joints, and suspected leak areas; escaping refrigerant produces visible bubbles. Reliable for larger leaks but less sensitive than electronic detection for very small leaks.
  • Nitrogen pressure testing — the system (or a section of it) is pressurized with dry nitrogen (sometimes with a small trace of refrigerant added for detector sensitivity) above normal operating pressure, then checked with soap bubbles or an electronic detector while under that positive pressure. This works because Type II systems are designed to hold positive pressure — pressurizing with nitrogen simply mimics and exaggerates normal operating conditions to reveal weak points.

All four of these methods rely, in one way or another, on refrigerant (or a pressurizing test gas) moving outward through a leak point under positive pressure. That's a critical detail, because it's exactly what breaks down when you move to Type III's low-pressure chillers — and that's where the exam's favorite "gotcha" questions live.

Type III Certification: Low-Pressure Appliances

Type III is the most specialized of the four EPA 608 sections, and most technicians consider it the hardest simply because it covers equipment fewer people work on day to day. But the core exam material centers on one idea that, once it clicks, makes most of the rest of the section straightforward.

What Equipment Requires Type III

Type III covers low-pressure appliances, which in practice means centrifugal chillers. These are large refrigeration systems used to chill water for building-wide air conditioning in hospitals, shopping malls, universities, office towers, and other large commercial or institutional buildings. They're a completely different scale of equipment from anything covered under Type II — chillers are typically permanently installed, maintained by specialized building-engineering staff, and serviced far less frequently than a residential split system.

Why Low-Pressure Systems Behave the Opposite of Type II

This is the single most important concept in the Type III section, and it's tested repeatedly in different forms. A low-pressure chiller operates below atmospheric pressure during normal operation — the refrigerant side of the system is under vacuum, not positive pressure.

The key concept: Because a Type III chiller runs below atmospheric pressure, a leak in the system doesn't push refrigerant out the way it does on a Type II system. Instead, atmospheric air and moisture get pulled in through the leak point, into the system. This is the exact opposite of what happens on a high-pressure Type II appliance, and it's the reason Type III systems require different leak-testing and maintenance procedures altogether.

This inward air leakage has real consequences for the chiller. Air and moisture entering the system are non-condensable — they don't turn to liquid the way refrigerant does inside the condenser — so they accumulate in the system over time, taking up space that should hold refrigerant, degrading heat transfer efficiency, and potentially introducing moisture that can cause acid formation when mixed with refrigerant and oil. That accumulation problem is exactly what purge units are built to solve, discussed further below.

Hot Water Leak Testing

Because a Type III chiller normally sits at a vacuum, you can't test it for leaks by pressurizing it with nitrogen and watching for gas escaping outward the same way you would on a Type II system — a vacuum system doesn't demonstrate its leak points that way. Instead, the standard method for testing a low-pressure chiller for leaks is to circulate hot water through the chiller (or otherwise heat the refrigerant charge) to raise the internal pressure of the machine above atmospheric pressure temporarily. Once the system pressure is elevated above atmospheric, it behaves briefly like a positive-pressure system, and leaks can then be located because refrigerant will actually escape outward at leak points, where it can be found using standard detection methods (electronic detectors, soap solution, etc.).

Exam tip: "Hot water" or "heating the system to raise pressure above atmospheric" is the classic tested phrase for Type III leak testing. If an exam question describes leak-testing a low-pressure chiller and one of the answer choices mentions pressurizing with nitrogen the same way you would a Type II system, that's the wrong answer for a Type III scenario — nitrogen pressurization is a Type II concept, not the standard Type III method.

Purge Unit Operation

Purge units are a piece of equipment unique to low-pressure chiller systems, and their operation is one of the most commonly tested Type III topics. Because Type III systems constantly draw in small amounts of air and moisture through leak points (a direct result of running below atmospheric pressure), chillers are equipped with a dedicated purge unit whose job is to continuously remove these non-condensable gases from the system without releasing significant refrigerant along with them.

A purge unit works, broadly, by isolating a portion of the system (typically near the top of the condenser, where non-condensables tend to collect since they don't condense with the refrigerant), cooling that mixture of air and refrigerant vapor down so the refrigerant portion condenses back into liquid and drains back into the system, while the remaining air and moisture — which won't condense at that temperature — get vented or collected separately. Properly functioning purge units are essential to keeping a chiller operating efficiently and are a routine maintenance and inspection point for technicians working on this equipment. A malfunctioning or poorly maintained purge unit can itself become a significant, ongoing source of refrigerant emissions if it's venting more refrigerant than air.

Refrigerant transition alert — R-410A phasing out for R-32 and R-454B: Under the EPA's AIM Act phasedown schedule, high-GWP refrigerants like R-410A are being progressively phased down in favor of lower-GWP alternatives, most notably R-32 and R-454B. Both of these replacement refrigerants carry an A2L classification — mildly flammable — which is a meaningful change from the non-flammable A1 refrigerants (like R-410A) that most Type II technicians have worked with for years. A2L refrigerants require different field handling: improved ventilation during service and storage to prevent flammable vapor accumulation, leak detectors rated and calibrated specifically for A2L sensitivity (a standard A1-rated sniffer may not reliably detect an A2L refrigerant), brazing and hot-work precautions to avoid ignition sources near a charged or recently-opened system, and updated cylinder storage and transport practices consistent with a flammable classification rather than a non-flammable one. Expect exam questions that test whether you recognize R-32 and R-454B as A2L (not A1) and understand that this changes standard field procedure — this is an actively evolving, high-priority area for both the Type II exam and real-world field practice.

High-Pressure Systems Low-Pressure Chillers Evacuation & Vacuum Levels Recovery Methods Purge Units R-410A & A2L Transition
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This test covers the venting ban and substantial leak repair rules under Clean Air Act Section 608, including the 15% comfort cooling and 35% process refrigeration thresholds, applied to both Type II and Type III equipment.

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This final mixed review test combines Type II and Type III topics from across the series: evacuation levels, recovery methods, leak detection, purge units, certification scope, refrigerant transition, and leak rate rules.

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Type II vs. Type III: Side-by-Side Comparison

Keeping these two systems straight is the single biggest key to passing both sections without confusing the rules. Use this table as a quick-reference before test day.

FeatureType IIType III
Pressure regimeHigh-pressure / very-high-pressure — operates above atmospheric pressureLow-pressure — operates below atmospheric pressure (vacuum)
Example equipmentResidential split systems, heat pumps, rooftop package units, light commercial refrigerationLarge centrifugal chillers (hospitals, malls, universities, large commercial buildings)
Leak directionRefrigerant leaks outward to atmosphereAir and moisture leak inward into the system
Standard leak test methodElectronic detector, UV dye, soap solution, nitrogen pressure testingHot water (or heat) to raise internal pressure above atmospheric, then standard detection at leak points
Evacuation requirement before opening system10" Hg (charge under 200 lbs) or 15" Hg (charge 200 lbs or more)Different framework specific to low-pressure equipment; not governed by the same 10"/15" Hg table used for Type II
Unique maintenance concernRefrigerant loss through leaks; recovery before serviceNon-condensable gas (air/moisture) buildup; purge unit operation and maintenance
Typical technician roleField service — installation, repair, seasonal maintenance on residential/light-commercial equipmentSpecialized building-engineering or chiller-service work, typically on large, permanently installed equipment

Refrigerant Recovery, Venting, and Leak Repair Rules That Apply to Both

Some rules on the Core/Type-agnostic side of the EPA 608 program apply across all appliance categories, including both Type II and Type III equipment, and they show up regularly on both exam sections.

The Venting Ban

Intentionally venting refrigerant to the atmosphere during service, maintenance, or disposal of any appliance has been illegal since July 1, 1992 for CFCs and HCFCs, and since November 15, 1995 for HFCs. This applies equally to Type II high-pressure equipment and Type III low-pressure chillers — there is no exemption for chillers just because they normally run at a vacuum. Violations can carry fines of up to $44,539 per day, per violation. De minimis releases that occur during the normal, good-faith course of making connections or during recovery are not considered venting violations, but deliberately releasing refrigerant to avoid the cost or time of proper recovery is.

Substantial Leak Repair Requirements

For appliances with a refrigerant charge of 50 lbs or more, federal rules define a "substantial leak rate" that triggers a repair obligation:

  • 15% per year for comfort cooling appliances (this includes most large chillers used for building air conditioning, which puts many Type III systems squarely in this category).
  • 35% per year for commercial and industrial process refrigeration.

Once a leak rate is determined to exceed the applicable threshold, the owner/operator is required to repair the leak within 30 days of discovering it (with some allowances for extended timelines under specific retrofit/retirement plans). This rule applies to large chillers under Type III just as it does to qualifying Type II equipment above the 50 lb threshold, so don't assume it's a Type-II-only rule.

Certification, Recordkeeping, and Technician Responsibilities

Beyond the equipment-specific mechanics of Type II and Type III, both exams draw on a shared set of program rules about who is allowed to do this work and what has to be documented.

Certification Cards and Scope of Work

Once you pass a section, the certifying organization issues a certification card identifying which type(s) you're certified in. A technician holding only Type II certification is not legally authorized to perform maintenance, service, or repair that could reasonably be expected to release refrigerant from a low-pressure chiller — that work requires Type III certification, regardless of how experienced the technician is with high-pressure equipment. The reverse is also true: Type III certification alone doesn't authorize work on Type II appliances. This is a frequent point of confusion for technicians who assume certification is a general credential rather than appliance-category specific.

Recordkeeping Requirements

Technicians and their employers are generally required to keep records related to refrigerant purchases, recovery, and disposal, and to be able to produce documentation showing that recovery equipment meets applicable standards. For appliances subject to substantial leak rate repair requirements, records of the leak rate calculation, the repair performed, and (where applicable) any follow-up verification test are part of standard compliance recordkeeping. While the exam doesn't typically require memorizing exact retention periods down to the day, candidates should understand that recordkeeping is a real, enforceable obligation tied to both Type II and Type III work — not an optional best practice.

Technician-Owned vs. Employer-Owned Equipment

Recovery equipment used for Type II and Type III work must meet EPA certification standards regardless of who owns it — an individual technician's personal recovery machine is held to the same requirements as equipment owned by a large mechanical contracting company. This matters for both exam sections because questions sometimes probe whether a candidate understands that the compliance obligation follows the equipment and the work being performed, not the size or type of the employer.

Common Exam Traps

These are the mistakes that show up most often when candidates study Type II and Type III together and let the details blur.

  • Swapping the evacuation table. The 10"/15" Hg vacuum levels are Type II-specific figures tied to charge size (under 200 lbs vs. 200 lbs or more). Don't apply that same table reflexively to a Type III question — low-pressure chillers are governed by a different framework, and an exam question describing a chiller isn't testing the 10"/15" Hg numbers.
  • Assigning nitrogen pressure testing to a low-pressure system. Nitrogen pressure testing is a Type II leak-detection method that works because those systems are designed to hold positive pressure. If a question describes a centrifugal chiller and one answer choice is "pressurize with nitrogen and check for bubbles," that's very likely a distractor — the standard Type III approach is to raise pressure with hot water/heat, not with an external gas charge the way Type II technicians do.
  • Confusing which direction a leak moves. On Type II, refrigerant leaks out. On Type III, air leaks in. Questions are frequently written to test this directly — read carefully whether the question is describing a high-pressure or low-pressure appliance before answering.
  • Mixing up push-pull with plain vapor recovery. Push-pull is specifically suited to systems with a large liquid charge, using the system's own pressure to assist recovery. If a question describes a small system or a mostly-vapor charge, standard vapor recovery — not push-pull — is usually the better answer.
  • Forgetting that purge units are a Type III-specific concept. There's no equivalent "purge unit" on a typical Type II split system or rooftop unit — it's a feature of low-pressure chillers dealing with constant air infiltration. If a question describes purge unit operation, it's a Type III question, even if it doesn't explicitly say "chiller."
  • Treating A2L refrigerants like older A1 refrigerants. As R-32 and R-454B become more common replacements for R-410A, expect questions that test whether you know these are mildly flammable (A2L) and require different ventilation, detection, and storage handling than non-flammable A1 refrigerants.
  • Assuming certification is one general credential. Passing Type II does not authorize you to service Type III equipment, and vice versa. Questions that describe a technician working outside their certified appliance category are testing whether you know certification is scope-limited, not a blanket authorization.
  • Applying the wrong leak-rate percentage. 15% per year applies to comfort cooling appliances (including most large chillers); 35% per year applies to commercial/industrial process refrigeration. Read the appliance description carefully — a chiller cooling a building for occupant comfort is a very different case from a process refrigeration system, even though both might be large systems with 50+ lb charges.

Study Tips for Type II and Type III

  • Study Type II first. It maps onto equipment most technicians already understand from field experience, and it builds the pressure/temperature and recovery-method foundation that Type III then modifies for the low-pressure case.
  • Anchor every fact to "above or below atmospheric." Nearly every difference between the two sections — leak direction, leak test method, why purge units exist — traces back to whether the appliance runs above or below atmospheric pressure. When you're unsure of an answer, ask yourself which pressure regime the question is describing first.
  • Memorize the evacuation table exactly. 10" Hg under 200 lbs, 15" Hg at 200 lbs or more, for recovery equipment made after November 15, 1993. This is a precise, frequently tested number — know it cold rather than approximating it.
  • Don't skip Type III just because it feels less relevant to your daily work. It's commonly considered the hardest section precisely because fewer technicians have hands-on chiller experience to fall back on, so deliberate study matters more here than on Type II.
  • Both exams are closed-book with a 70% passing score. Treat memorization of exact figures (vacuum levels, fine amounts, leak-rate percentages, key dates) as non-negotiable — you won't have reference material available during the actual test.
  • Practice distinguishing recovery methods with scenario questions rather than memorizing definitions in isolation. The exam tests application ("which method should you use here"), not just recall of what each method is.
  • Build a short reference sheet of exact numbers before your test date: 10"/15" Hg evacuation levels, 70% passing score, 15%/35% leak-rate thresholds, 30-day repair window, July 1992/November 1995 venting-ban dates, and the $44,539 per-day fine ceiling. Reviewing this short list repeatedly in the days before the exam is more efficient than re-reading full study guides.

Frequently Asked Questions

What's the actual difference between Type II and Type III certification?

Type II covers high-pressure and very-high-pressure appliances — residential split systems, heat pumps, rooftop units, and light commercial refrigeration — which operate above atmospheric pressure. Type III covers low-pressure appliances, which in practice means large centrifugal chillers that operate below atmospheric pressure. The pressure regime drives nearly every other difference between the two, including leak direction, leak testing method, and recovery requirements.

Do I need both Type II and Type III to get Universal certification?

Yes. Universal certification requires passing all four sections: Core, Type I, Type II, and Type III. If you only need to service small appliances and high-pressure equipment, you could pursue Core + Type I + Type II without Type III, but you would not hold Universal certification, and you would not be authorized to work on low-pressure chillers.

What evacuation vacuum level do I need before opening a Type II system?

It depends on the system's refrigerant charge, assuming recovery equipment manufactured after November 15, 1993: 10 inches of mercury (Hg) for systems containing less than 200 lbs of refrigerant, and 15 inches of mercury (Hg) for systems containing 200 lbs or more.

Why can't you just pressurize a chiller with nitrogen to find a leak the same way you would a Type II system?

Because a Type III chiller normally runs below atmospheric pressure, a leak pulls air inward rather than pushing refrigerant outward — the opposite of a Type II system. Standard nitrogen pressure testing is built around detecting outward leakage from a positive-pressure system. To test a low-pressure chiller, technicians instead circulate hot water (or otherwise apply heat) to temporarily raise the system's internal pressure above atmospheric, at which point it behaves like a positive-pressure system and leaks can be located with standard detection methods.

What is a purge unit and why does it matter for the exam?

A purge unit is equipment specific to low-pressure chillers that continuously removes non-condensable gases — mainly air and moisture that leak into the system because it runs below atmospheric pressure — while returning any refrigerant vapor mixed in back to the system. It's heavily tested on the Type III exam because it's a concept unique to low-pressure equipment with no real equivalent on Type II systems.

When should I use push-pull recovery instead of standard vapor or liquid recovery?

Push-pull is intended for systems with a large liquid refrigerant charge. It uses the system's own pressure differential to help push liquid refrigerant into the recovery cylinder while the recovery machine pulls vapor from the cylinder to sustain that differential, which recovers refrigerant much faster than standard vapor recovery alone on a large system. For smaller charges or systems where the refrigerant is largely in vapor form, standard vapor or liquid recovery is typically the more appropriate method.

Are R-32 and R-454B handled differently than R-410A in the field?

Yes. R-32 and R-454B are both classified A2L — mildly flammable — unlike R-410A, which is non-flammable (A1). Working with A2L refrigerants calls for different practices: adequate ventilation during service and storage, leak detection equipment rated for A2L sensitivity, care around ignition sources during brazing or other hot work, and storage/transport handling consistent with a flammable classification. As the EPA's AIM Act phasedown continues to push the industry away from high-GWP refrigerants like R-410A, expect A2L refrigerants and their handling requirements to appear more frequently on updated exam material.

Is Type III really harder than Type II?

Most technicians and instructors consider it the more challenging of the two, mainly because far fewer people have hands-on experience with centrifugal chillers compared to the split systems and rooftop units covered under Type II. The core concepts (low pressure, inward air leakage, hot water leak testing, purge units) are not inherently more complex than Type II material, but they're less intuitive if you've never worked on a chiller, so deliberate study — rather than relying on field experience — matters more for this section.

Can I use my Type II certification to work on a chiller if I'm experienced with refrigeration in general?

No. Certification under EPA Section 608 is scope-limited to the appliance category you're certified for. Type II certification authorizes work on high-pressure and very-high-pressure appliances; it does not authorize maintenance, service, or repair on low-pressure appliances like centrifugal chillers, no matter how much general refrigeration experience a technician has. Working on a chiller requires passing the Type III section specifically.

What happens if a substantial leak isn't repaired within the required timeframe?

Once a leak rate is confirmed to exceed the substantial leak threshold (15% per year for comfort cooling, 35% per year for commercial/industrial process refrigeration, on appliances with 50 lbs or more of charge), the owner/operator is required to repair it within 30 days of discovery, with limited allowances for extended timelines under certain retrofit or retirement plans. Failing to repair within the required window is a compliance violation separate from the venting-ban penalties, and it applies to qualifying equipment under both Type II and Type III categories.