Guide

Recovery requirements: the numbers on the 608 exam that matter in the truck

The small appliance 80 and 90 percent recovery split, the four inches of mercury alternative, the MVAC 102 mm figure, and the self-contained versus system-dependent distinction, explained for the exam and the field.

Recovery is the working heart of Section 608. The venting prohibition tells you what you cannot do with refrigerant, and the recovery requirements tell you what you must do instead: capture it, to a defined standard, before an appliance is opened or scrapped. The standards are expressed as numbers, and the numbers are the most heavily tested material in the small appliance portion of the exam because they encode real decisions a technician makes at a real machine. How much refrigerant must come out. What changes when the compressor is dead. What counts as good enough when a percentage cannot be measured. And what standard applies when the appliance is not a kitchen refrigerator but a vehicle at a scrapyard.

This guide covers the small appliance recovery requirements and the logic behind them: the 80 and 90 percent split and why the condition of the compressor moves the number, the four inches of mercury vacuum alternative, the 102 mm of mercury figure for motor vehicle air conditioning disposal, and the distinction between self-contained and system-dependent recovery equipment that the exam returns to again and again. None of this is presented as a service procedure. It is the regulatory floor and the reasoning that makes it memorable, which is exactly the altitude the exam tests at.

What counts as a small appliance

The recovery numbers in this guide belong to small appliances, so the definition comes first. A small appliance is a product manufactured, charged, and hermetically sealed in a factory with 5 pounds or less of refrigerant. Household refrigerators and freezers, window air conditioning units, dehumidifiers, and similar factory sealed products live here. This is also the equipment class covered by Type I certification, which is why the recovery percentages below are core Type I exam material.

Every word in the definition is testable. The charge limit is 5 pounds or less. The unit is factory charged and hermetically sealed. A system assembled and charged in the field is not a small appliance no matter how little refrigerant it holds, because it was not sealed at a factory. Exam writers like to build wrong answers out of definitions that are almost right, and a field charged system described as a small appliance is one of their favorite constructions.

The 80 and 90 percent split

When refrigerant is recovered from a small appliance using recovery equipment, the required recovery percentage depends on two things: the vintage of the recovery equipment and whether the appliance's compressor works. Recovery equipment manufactured before November 15, 1993 must recover 80 percent of the refrigerant in the appliance. Recovery equipment manufactured on or after that date must recover 90 percent when the compressor of the appliance is operating, and 80 percent when the compressor is not operating.

November 15, 1993 is the dividing line because that is when equipment certification requirements changed, and the regulation did not pretend that older recovery machines could suddenly meet a standard they were never built for. Older equipment carries the 80 percent requirement across the board. Newer equipment is held to 90 percent, but only when the appliance itself can help, which brings us to the compressor.

Why the compressor condition changes the number

The 90 versus 80 split on modern equipment is not an arbitrary discount for broken machines. It reflects what is physically happening inside a sealed system during recovery. Refrigerant in a small appliance does not sit conveniently in one place as a gas waiting to be drawn out. A meaningful portion of it is dissolved in the compressor's lubricating oil and settled in the low spots of the circuit. A compressor that can run helps liberate that refrigerant: running the appliance warms the oil and moves refrigerant through the circuit, so more of the charge is actually available to the recovery machine as vapor that can be captured.

When the compressor is dead, that assistance is gone. Refrigerant stays dissolved in cold oil and trapped in the low points, and no recovery machine on the outside of a hermetically sealed system can coax all of it out. The regulation acknowledges the physics: with a working compressor the standard is 90 percent, and without one it drops to 80 percent. The number tracks what competent recovery can realistically achieve, not what a perfect laboratory could.

This reasoning is worth carrying into the exam room because it converts a memorization item into a derivation. If you remember only that a dead compressor makes recovery harder, you can reconstruct which situation gets 90 and which gets 80. The exam question that presents a small appliance with a burned out compressor and asks for the required recovery percentage is testing exactly this: candidates who memorized 90 without the condition attached will pick the wrong answer, and candidates who understand why the compressor matters will not.

The four inches of mercury alternative

Percentages have an obvious practical problem: at a machine in the field, nobody can directly measure what percentage of an unknown remaining charge has been captured. So the regulation provides an alternative standard expressed in something a technician can actually read. Instead of recovering 80 or 90 percent, the requirement can be satisfied by evacuating the small appliance to four inches of mercury vacuum.

Four inches of mercury vacuum is a modest vacuum, well short of the deep vacuums used elsewhere in refrigeration work, and that is the point. It is a level chosen to demonstrate that the recoverable refrigerant has been captured from a small sealed system, achievable with certified recovery equipment in reasonable time. On a gauge, it is an observable, recordable endpoint. The regulation is giving the technician a choice of two ways to prove the same thing: hit the percentage, or hit the vacuum.

For the exam, hold on to the word or. The percentage standard and the four inches of mercury standard are alternatives, and either satisfies the requirement. A question may present a scenario where the technician evacuated to four inches of mercury and ask whether the requirement was met, with a distractor implying the percentage also had to be verified. It did not. One standard or the other, not both.

MVAC disposal and the 102 mm figure

Motor vehicle air conditioners occupy their own corner of the rules, and the corner the 608 exam cares about is disposal. When a motor vehicle air conditioner is being disposed of, the requirement is to reduce the system to 102 mm of mercury vacuum, or to handle the refrigerant under the rules that govern motor vehicle air conditioning work. As with the small appliance standards, the structure is a choice between a measurable endpoint and an alternative compliance path.

Why does a 608 exam ask about vehicles at all? Because appliances and vehicles meet at the end of life. Scrap yards, salvage operations, and appliance recyclers deal with refrigerant circuits from both worlds, and the disposal rules are written so that a vehicle air conditioner headed for the shredder does not become a venting event simply because it fell between two regulatory programs. The 102 mm of mercury figure is the disposal standard a 608 candidate is expected to recognize.

The testable content here is deliberately narrow. Know the number, know that it attaches to motor vehicle air conditioner disposal, and know that following the motor vehicle rules is the alternative path. Resist the urge to import more detail than the exam asks for. The question pattern is recognition, not vehicle service knowledge.

Self-contained versus system-dependent recovery equipment

The equipment side of recovery has its own tested distinction. Recovery equipment comes in two kinds. Self-contained equipment has its own means of moving refrigerant: it can pull refrigerant out of an appliance under its own power, without any help from the appliance it is servicing. System-dependent equipment has no independent means of moving refrigerant and relies on the appliance's own components, most importantly its compressor, or on pressure differences the system itself provides, to push the charge into a recovery container.

The distinction matters because it decides what a given piece of equipment can honestly accomplish. A system-dependent device is at the mercy of the appliance. If the appliance's compressor is dead and the system holds no useful pressure, a system-dependent device has nothing to work with. Self-contained equipment brings its own capability and does not care whether the appliance can participate. That is the conceptual line the exam draws, and nearly every question about the two categories is a restatement of it.

Connect this back to the recovery percentages and the whole small appliance section snaps into one picture. The regulation sets performance standards that certified recovery equipment can meet, adjusts the standard when the appliance's compressor cannot assist, and distinguishes equipment that works alone from equipment that needs the appliance's help. Every number and every category in this guide is answering the same underlying question: what does it actually take to get the refrigerant out of a sealed system before that system is opened or scrapped.

How these become exam questions

The recovery material generates some of the most formulaic questions on the exam, which is good news for a prepared candidate. The variables are few: equipment vintage relative to November 15, 1993, compressor working or not, percentage standard or vacuum alternative, self-contained or system-dependent, small appliance or MVAC disposal. Exam writers combine those variables into scenarios, and the combinations repeat.

• A small appliance with a working compressor, recovered with equipment made after November 15, 1993: 90 percent is required.
• The same appliance with a dead compressor: the requirement drops to 80 percent.
• Recovery equipment manufactured before November 15, 1993: 80 percent, regardless of the compressor.
• A technician evacuates a small appliance to four inches of mercury vacuum instead of measuring a percentage: the requirement is satisfied, because the standards are alternatives.
• A motor vehicle air conditioner at disposal: reduce to 102 mm of mercury vacuum or follow the motor vehicle rules.
• A recovery device that relies on the appliance's compressor to move refrigerant: system-dependent. One that moves refrigerant under its own power: self-contained.

Notice what is missing from that list: procedures. The exam does not ask how to connect equipment, in what order to operate anything, or how to handle refrigerant containers, and this guide has deliberately stayed at the same altitude. What the exam wants is the regulatory floor: the numbers, the conditions that select between them, and the categories of equipment. Train at that altitude and the recovery section becomes the most predictable part of the test.

Learn the definitions first, then the split, then the alternatives. Small appliance means factory sealed with 5 pounds or less. Eighty percent for old equipment always, 90 for new equipment with a working compressor, 80 when it is dead, or four inches of mercury as the alternative endpoint. And 102 mm of mercury when the appliance being disposed of is a vehicle's. That handful of facts, held with the reasoning that generated them, covers the recovery ground the exam walks every single time.

Test yourself on the recovery numbers under exam conditions. Take a free 608 practice exam.

The tools of the certified tech

Elitech digital manifold setThe gauge set is the trade's daily instrumentVIVOHOME 4CFM vacuum pumpEvacuation is half of what 608 regulatesVEVOR recovery machineRecovery is the other halfFieldpiece DR58 leak detectorLeak detection is a Group II exam areaElitech refrigerant scaleCharge tracking runs on the scale

Certification is the legal floor; these are the working instruments beside it. The full kit page.