5 Universal Certification Practice and Review

Certification scope and exam map

EPA Section 608 Universal certification covers the Core and all three equipment types: Type I for small appliances, Type II for high- or very high-pressure appliances other than small appliances and motor-vehicle air conditioners, and Type III for low-pressure appliances. To earn Universal certification, technicians must pass the applicable exams through an EPA-approved certifying organization. The Core exam must be proctored and is not open-book.

Environmental effects and venting

CFCs and HCFCs can deplete stratospheric ozone. HFCs contain no chlorine and have zero ozone-depletion potential, but some have high global-warming potential. Therefore, zero ODP does not mean zero climate impact. Refrigerants are not automatically interchangeable; check compatibility with the equipment and lubricants before using a refrigerant as a replacement.

Section 608 generally prohibits intentionally venting refrigerant during service, repair, or disposal. Limited exceptions include de minimis releases during good-faith recovery efforts and certain specifically exempt substitutes and uses.

Recover, recycle, and reclaim

The three refrigerant-handling terms describe different levels of processing:

• Recover: Remove refrigerant and store it without necessarily processing it.

• Recycle: Clean refrigerant for reuse, generally in equipment owned by the same person.

• Reclaim: Reprocess refrigerant and verify that it meets applicable purity specifications.

For example, removing refrigerant from an appliance and storing it in a recovery cylinder without processing it is recovering. Cleaning refrigerant for reuse without meeting full reclamation specifications is recycling. Recovered refrigerant transferred to a different owner generally must be reclaimed by an EPA-certified reclaimer.

Safe work and cycle basics

Never use oxygen or compressed air to pressure-test a refrigeration system; use regulated nitrogen instead. Use a regulator and suitable pressure-relief protection, wear appropriate protective equipment, and never exceed the equipment’s pressure limits. Oxygen and compressed air can create dangerous conditions in a refrigeration system.

Avoid mixing refrigerants. Do not overfill recovery cylinders because liquid refrigerant expands as it warms. After repairing a system, evacuate it to remove air and moisture before charging.

Basic refrigeration cycle

The compressor raises refrigerant vapor pressure and temperature. The condenser rejects heat and condenses the vapor to liquid. The metering device lowers pressure. In the evaporator, refrigerant absorbs heat as it boils.

Type I small-appliance recovery

For small-appliance recovery, the required recovery level depends on compressor function and the recovery-equipment manufacture date. With a functional compressor and recovery equipment made after $\text{November 15, 1993}$, recover at least $90\%$, or evacuate the appliance to $4$ inches of mercury vacuum. If the compressor is not functional, the recovery threshold is $80\%$. The $80\%$ threshold also applies when using equipment made before $\text{November 15, 1993}$.

For an appliance with an inoperative compressor, a system-dependent (passive) recovery device can be used with access installed on both the high and low sides and appropriate recovery procedures. This device relies on appliance pressure differences rather than an independent recovery machine.

Type II high-pressure recovery

EPA’s service-practice table gives different evacuation levels for high-pressure appliances according to charge size and manufacture date. For a post-$\text{November 15, 1993}$ high-pressure appliance or isolated component with a full charge of $200$ pounds or more, the listed level is $10$ inches of mercury vacuum. For a high-pressure appliance with less than $200$ pounds, the listed level is $0$ inches of mercury vacuum. Thus, a post-$1993$ appliance charged with $250$ pounds has a target of $10$ inches of mercury vacuum, while one charged with $100$ pounds has a target of $0$ inches of mercury vacuum. The table’s inches of mercury are relative to standard atmospheric pressure.

System-dependent recovery equipment must not be used on a system containing more than $15$ pounds of refrigerant. Use suitable self-contained recovery equipment and follow its instructions.

A recovery reading may reach the required vacuum and then rise again after a short wait. Refrigerant may remain as liquid or be dissolved in oil and then boil off into the system. Wait and continue recovery as needed rather than treating the first vacuum reading as proof that recovery is complete.

Type III low-pressure appliances

The EPA service-practice table lists an evacuation level of $25$ mm Hg absolute for low-pressure appliances, regardless of whether they were manufactured before or after $\text{November 15, 1993}$. This is an absolute-pressure value, not a vacuum reading in inches of mercury.

When recovering refrigerant from a water-cooled low-pressure chiller, circulate water or remove it from the tubes to prevent freezing as refrigerant pressure and temperature fall. When recharging, introduce vapor before liquid to reduce the risk of freezing water in the tubes.

If a low-pressure chiller’s purge unit operates unusually often, suspect that air or other noncondensables may be entering through a leak. Inspect and leak-test the system; excessive purging is a leak clue.

Oil removal and exam review

Before removing oil from a stationary refrigeration appliance, reduce system pressure to no greater than $5$ psig because refrigerant can remain dissolved in the oil. Alternatively, drain the oil into a receiver and bring that receiver to no greater than $5$ psig.

For exam review, distinguish the small-appliance $80\%$ and $90\%$ recovery thresholds, the Type II evacuation levels, and the Type III absolute-pressure value. Also remember that Universal certification covers all equipment types, intentional venting is generally prohibited, and circulating or removing chiller-tube water helps prevent freezing during recovery.

Applying the requirements

The practice questions in this guide are not official exam questions. Use current EPA and certifying-organization materials to confirm rules and exam procedures. For every job, avoid intentional venting, use appropriate equipment and safe procedures, and follow applicable regulations and manufacturer instructions.