9 Universal Certification Practice Exam

Exam structure and scope

Universal certification covers the Core, Type I, Type II, and Type III topics. The EPA exam standard specifies 100 questions: 25 Core questions and 25 for each appliance category. The stated passing score for a closed-book exam is $70\%$. Actual tests are administered by EPA-approved certifying programs; the practice set is not an official exam or a reproduction of EPA test-bank questions.

Preparation should include the current EPA topic list and applicable regulations. Requirements and procedures can vary with appliance type, equipment, refrigerant, and repair situation.

Core refrigerant practices

Chlorofluorocarbons (CFCs) can deplete stratospheric ozone because ultraviolet radiation breaks them down in the stratosphere, releasing chlorine atoms that contribute to ozone destruction.

Section 608 generally prohibits intentionally venting ozone-depleting refrigerants and most substitutes during service, repair, or disposal. Limited exceptions include de minimis releases during good-faith recovery efforts and releases EPA has specifically exempted.

Recovery removes refrigerant from equipment. Recycling reduces contaminants for reuse, usually without meeting the purity standard required for reclamation. Reclamation processes recovered refrigerant to applicable specifications and verifies its quality. Keep different refrigerants segregated and identify cylinders: contamination can make refrigerant unsuitable for reuse or reclamation and can create equipment or safety problems.

Do not fill a recovery cylinder beyond its permitted limit. Liquid refrigerant expands as it warms, and a cylinder without adequate vapor space can experience a rapid pressure increase. Follow cylinder markings, applicable requirements, and safe handling procedures.

Type I: Small appliances

A small appliance is generally factory-manufactured, charged, and hermetically sealed with five pounds or less of refrigerant.

EPA-certified recovery equipment for a small appliance must be capable of recovering at least $90\%$ of the refrigerant when its compressor is functional. The required percentage is $80\%$ when the compressor is not functional. The $80\%$ standard also applies to equipment manufactured before November 15, 1993; another permitted option is evacuation to $4\ \text{inches of mercury vacuum}$. Equipment instructions and the applicable recovery procedure still matter.

If an appliance has no service access ports, an approved piercing access device can provide access for recovery equipment. Follow the device instructions and appliance-manufacturer guidance; do not release refrigerant to create access.

Type II: High-pressure appliances

At the beginning of recovery from a system containing both liquid and vapor refrigerant, recovering available liquid first generally removes more refrigerant per unit time than vapor-only recovery. Continue recovering vapor as required; recovering liquid alone does not empty the system.

For a non-major repair on a high- or very-high-pressure appliance that will not be evacuated to the atmosphere after repair, the appliance must reach $0\ \text{psig}$ before it is opened.

Do not energize a hermetic compressor while the system is under a deep vacuum. Operating it in that condition can cause damage, including electrical arcing in the low-pressure environment.

Many zeotropic refrigerant blends should be charged as liquid when required by the refrigerant and equipment instructions. This helps reduce fractionation and preserve the intended blend composition. Follow manufacturer instructions and use a safe charging method.

Type III: Low-pressure appliances

A purge unit removes noncondensables from a low-pressure system. Abnormally frequent purging can indicate that air or other noncondensables are entering the system, potentially through a leak.

During evacuation, circulate or remove water in the chiller. Evacuation lowers pressure and temperature, and managing the water helps prevent it from freezing in the tubes and potentially damaging them.

Before removing oil from a refrigeration appliance, reduce refrigerant pressure to no greater than $5\ \text{psig}$. Oil can contain dissolved refrigerant, and EPA service-practice requirements prohibit changing oil above that pressure.

When recharging a low-pressure centrifugal chiller, introduce refrigerant vapor before liquid to help prevent water in the tubes from freezing. Use the manufacturer’s specified charging procedure.

After the appliance reaches its required recovery vacuum, wait briefly and check whether pressure rises. A rise can indicate refrigerant remains in liquid or oil, or is boiling out of oil. Continue recovery if pressure rises and refrigerant remains.

Recovery when a leak limits evacuation

If a leak prevents reaching the specified evacuation level without substantially contaminating the recovered refrigerant, isolate leaking and non-leaking sections where possible. Evacuate sound, non-leaking sections to the required level and the leaking section to the lowest attainable level, no higher than $0\ \text{psig}$. Do not vent the remaining refrigerant or leave all refrigerant in the appliance.

Pressure testing and safe handling

Use dry nitrogen, a regulator, and appropriate pressure controls when pressure-testing a refrigeration system. Never use oxygen or compressed air for pressure testing: oxygen can react violently with oil, while air introduces oxygen and moisture.

Across appliance types, prevent intentional refrigerant release, use suitable recovery equipment, keep refrigerants segregated, observe cylinder fill limits, and adapt recovery and repair procedures to the appliance and situation.