Test de práctica EPA 608: Core, Type I a III

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Las 15 preguntas de un vistazo

¿Prefieres leer antes de jugar? Abajo están todas las preguntas de la muestra. Las respuestas y explicaciones quedan plegadas hasta que las abras.

1. 1. Which element, released when CFC molecules break apart in the stratosphere, destroys ozone?

   • A. Nitrogen
   • B. Chlorine
   • C. Carbon
   • D. Hydrogen
   Ver respuesta y explicación

   Respuesta: B. Chlorine

   Ultraviolet light breaks CFC molecules apart high in the atmosphere and frees chlorine atoms. One chlorine atom can destroy thousands of ozone molecules because it is not used up in the reaction, which is why even small releases matter and why the Montreal Protocol targeted chlorine-containing refrigerants first.

2. 2. Which list ranks refrigerant types from the highest to the lowest ozone depletion potential?

   • A. CFCs, then HCFCs, then HFCs
   • B. HCFCs, then CFCs, then HFCs
   • C. HFCs, then HCFCs, then CFCs
   • D. CFCs, then HFCs, then HCFCs
   Ver respuesta y explicación

   Respuesta: A. CFCs, then HCFCs, then HFCs

   CFCs such as R-12 contain the most chlorine and have the highest ozone depletion potential. HCFCs such as R-22 contain hydrogen, which makes them break down sooner in the lower atmosphere, so their potential is lower. HFCs such as R-134a and R-410A contain no chlorine, so they do not deplete ozone, although many of them are strong greenhouse gases.

3. 3. Complete the sentence.

   To _____ refrigerant means to reprocess it until it meets the purity specifications EPA sets for refrigerant sold for reuse, which must be confirmed by chemical analysis.

   Opciones para el hueco 1: recover, recycle, reclaim, recharge

   Ver respuesta y explicación

   Respuesta: reclaim

   Recover means removing refrigerant from an appliance and storing it in an external container. Recycle means cleaning it, usually by separating oil and filtering, for reuse in equipment of the same owner. Reclaim is the only one that brings refrigerant back to new product specifications, and it is done by an EPA-certified reclaimer, not in the field.

4. 4. You need to pressurize a system to check for leaks. What should you use?

   • A. Oxygen from a welding cylinder
   • B. Compressed shop air
   • C. Dry nitrogen through a pressure regulator and relief valve
   • D. Liquid refrigerant charged until the system reaches full pressure
   Ver respuesta y explicación

   Respuesta: C. Dry nitrogen through a pressure regulator and relief valve

   Dry nitrogen is inert and contains no moisture. Oxygen can react violently with compressor oil and cause an explosion, and shop air brings in moisture and also contains oxygen. A nitrogen cylinder holds far more pressure than a system can take, so the regulator and relief valve are not optional.

5. 5. Which statements about the Clean Air Act venting prohibition are correct?

   Marca todas las que correspondan.

   • A. Knowingly venting CFC or HCFC refrigerant during service, repair or disposal is prohibited.
   • B. The prohibition also covers HFC substitutes such as R-134a and R-410A.
   • C. Venting is allowed when a system holds less than 5 pounds of refrigerant.
   • D. Small de minimis releases that happen while you follow proper recovery practices are not a violation.
   • E. HFCs may be vented freely because they do not deplete ozone.
   Ver respuesta y explicación

   Respuesta: A. Knowingly venting CFC or HCFC refrigerant during service, repair or disposal is prohibited., B. The prohibition also covers HFC substitutes such as R-134a and R-410A., D. Small de minimis releases that happen while you follow proper recovery practices are not a violation.

   The prohibition applies at servicing and at disposal, and it extends to substitute refrigerants like HFCs, not only to ozone-depleting ones. What is tolerated is the unavoidable minimal release that happens during good-faith recovery, such as the small amount lost when you disconnect hoses. Charge size does not create an exemption, and small appliances must still be recovered.

6. 6. Why should a refrigerant cylinder never be filled to more than 80 percent of its capacity?

   • A. Because EPA charges a fee on cylinders that are full
   • B. Because refrigerant cannot be recovered after the cylinder passes 80 percent
   • C. Because the scale reading becomes inaccurate above 80 percent
   • D. Because liquid expands as it warms, and a cylinder with no vapor space left can rupture
   Ver respuesta y explicación

   Respuesta: D. Because liquid expands as it warms, and a cylinder with no vapor space left can rupture

   The space above the liquid gives it room to expand. If a full cylinder warms up, for example in a truck on a hot day, the liquid can fill the whole cylinder and hydrostatic pressure rises very fast. That is why recovery cylinders are weighed during filling, or have a float switch, and are never filled past 80 percent.

7. 7. Complete the sentence.

   Under Section 608, a small appliance is one that is fully manufactured, charged and hermetically sealed in a factory with _____ or less of refrigerant.

   Opciones para el hueco 1: 1 pound, 2 pounds, 5 pounds, 10 pounds

   Ver respuesta y explicación

   Respuesta: 5 pounds

   The definition has two parts: 5 pounds or less, and factory sealed. A household refrigerator, a window air conditioner or a dehumidifier qualifies. A unit that is field-assembled does not, even if its charge is small, and working on small appliances is what Type I certifies you for.

8. 8. You are recovering refrigerant from a small appliance whose compressor does not run, using recovery equipment made after November 15, 1993. What is the minimum requirement?

   • A. Recover 100 percent of the charge
   • B. Recover 90 percent of the charge
   • C. Recover 80 percent of the charge, or evacuate to 4 inches of mercury vacuum
   • D. Recover 50 percent of the charge
   Ver respuesta y explicación

   Respuesta: C. Recover 80 percent of the charge, or evacuate to 4 inches of mercury vacuum

   With equipment made after that date, you must recover 90 percent of the charge when the appliance compressor works and 80 percent when it does not, or pull the appliance down to 4 inches of mercury vacuum in either case. A running compressor helps push refrigerant out, which is why the bar is higher when it works.

9. 9. When you recover from a small appliance with an inoperative compressor, why should you install access valves on both the high side and the low side?

   • A. Because refrigerant can stay trapped on one side of the system without a running compressor to move it
   • B. Because the law requires two valves on every appliance, whatever its size
   • C. Because a single valve would let air into the system
   • D. Because the high side valve is needed to add oil during recovery
   Ver respuesta y explicación

   Respuesta: A. Because refrigerant can stay trapped on one side of the system without a running compressor to move it

   A working compressor moves refrigerant through the system, so one access point can be enough. When it does not run, refrigerant can be held on either side of the metering device, and accessing both sides gets it out faster and more completely. Solderless piercing valves used for this should be removed when the job is done, because they tend to leak over time.

10. 10. Complete the sentence.

    System-dependent recovery equipment may not be used on an appliance with a full charge of more than _____ of refrigerant, unless it is a pump-out unit permanently attached to the appliance.

    Opciones para el hueco 1: 5 pounds, 15 pounds, 50 pounds, 200 pounds

    Ver respuesta y explicación

    Respuesta: 15 pounds

    System-dependent equipment relies on the appliance's own compressor or pressure to move refrigerant, so it recovers too slowly and too incompletely for larger systems. Above 15 pounds you need self-contained recovery equipment, which has its own compressor and works without help from the appliance.

11. 11. A high-pressure appliance has a full charge of less than 200 pounds. Using recovery equipment made after November 15, 1993, to what level must you evacuate it before opening it?

    • A. 0 inches of mercury
    • B. 10 inches of mercury vacuum
    • C. 15 inches of mercury vacuum
    • D. 25 millimeters of mercury absolute
    Ver respuesta y explicación

    Respuesta: A. 0 inches of mercury

    For high-pressure appliances, EPA's evacuation table sets 0 inches of mercury for a charge under 200 pounds and 10 inches of mercury vacuum for 200 pounds or more, with modern recovery equipment. The 25 millimeters of mercury absolute level belongs to low-pressure appliances. After you reach the level, wait a few minutes and watch the gauges, because a rise in pressure means refrigerant is still in the system.

12. 12. Which of these are signs of a leak in a high-pressure system?

    Marca todas las que correspondan.

    • A. Oily residue around a fitting or brazed joint
    • B. Head pressure holding steady at its normal reading
    • C. Bubbles forming in a soap solution brushed over a joint
    • D. An electronic leak detector alarming at one spot
    • E. A clean, dry joint with no residue
    Ver respuesta y explicación

    Respuesta: A. Oily residue around a fitting or brazed joint, C. Bubbles forming in a soap solution brushed over a joint, D. An electronic leak detector alarming at one spot

    Refrigerant carries compressor oil with it, so oil stains at a joint are the classic visual sign of a leak. Soap bubbles and an electronic detector confirm the exact spot. Before you charge or recharge equipment, leak test it, because adding refrigerant to a leaking system only releases more of it.

13. 13. On a large high-pressure system, why do technicians often start by recovering liquid refrigerant?

    • A. Because liquid recovery removes moisture from the system
    • B. Because liquid moves much more refrigerant in less time than vapor
    • C. Because vapor cannot legally be recovered
    • D. Because liquid recovery makes evacuation unnecessary
    Ver respuesta y explicación

    Respuesta: B. Because liquid moves much more refrigerant in less time than vapor

    The same volume of liquid holds far more refrigerant than vapor, so pulling liquid first removes most of the charge quickly. You still have to recover the vapor afterwards and reach the required evacuation level. Shorter hoses, larger diameter hoses and removing valve cores also speed up recovery.

14. 14. When you recharge a low-pressure chiller that has been evacuated to a deep vacuum, why do you add refrigerant vapor before liquid?

    • A. Because liquid would contaminate the purge unit
    • B. Because vapor is cheaper than liquid
    • C. Because the chiller can only be charged through the condenser
    • D. Because liquid boiling at very low pressure can freeze the water in the tubes
    Ver respuesta y explicación

    Respuesta: D. Because liquid boiling at very low pressure can freeze the water in the tubes

    At a deep vacuum, liquid refrigerant flashes and gets very cold, cold enough to freeze the water in the evaporator tubes and split them. Charging vapor first raises the pressure until the refrigerant's saturation temperature is above freezing, and then liquid can follow. Centrifugal chillers are charged through the evaporator charging valve.

15. 15. Which statements about low-pressure chillers are correct?

    Marca todas las que correspondan.

    • A. They run at higher pressures than R-410A systems.
    • B. Because parts of the system run below atmospheric pressure, leaks let air and moisture in rather than letting refrigerant out.
    • C. A purge unit removes air and other noncondensables from the system.
    • D. Leak testing should be done by pressurizing the system with oxygen.
    • E. During refrigerant evacuation, the water in the tubes should be circulated or drained to prevent freezing.
    Ver respuesta y explicación

    Respuesta: B. Because parts of the system run below atmospheric pressure, leaks let air and moisture in rather than letting refrigerant out., C. A purge unit removes air and other noncondensables from the system., E. During refrigerant evacuation, the water in the tubes should be circulated or drained to prevent freezing.

    Low-pressure refrigerants such as R-123 boil just above room temperature at atmospheric pressure, so the evaporator of a running chiller sits in a vacuum and a leak pulls air in. That air and moisture raise pressure and cut efficiency, which is what the purge unit is there to remove. Water in the tubes can freeze as pressure drops during evacuation, so keep it moving or drain it.

Cómo funciona el examen EPA 608

La Section 608 de la Clean Air Act obliga a certificarse a cualquiera que mantenga, revise, repare o deseche equipos que puedan liberar refrigerante. La norma es federal, así que la misma certificación vale en todos los estados. Hay cuatro tipos de certificación. Type I cubre los electrodomésticos pequeños, es decir, aparatos sellados de fábrica con 5 libras de refrigerante o menos, como las neveras domésticas y los aires acondicionados de ventana. Type II cubre los equipos de alta y muy alta presión, que incluyen la mayor parte del aire acondicionado residencial y comercial. Type III cubre los equipos de baja presión, sobre todo enfriadoras centrífugas. Universal significa que aprobaste los tres tipos.

Cada examen incluye una sección Core. Según la norma de la EPA, cada examen tiene al menos 25 preguntas del grupo Core y al menos 25 de cada tipo al que te presentas, así que un examen Universal tiene 100 preguntas. La nota de aprobado que fija la norma es del 70 por ciento para los exámenes a libro cerrado de Type I, Type II, Type III y Universal, y del 84 por ciento para un examen de Type I hecho por correo. Type II y Type III se tienen que hacer a libro cerrado y con supervisor. Un examen de Type I por correo, o una sección Core hecha a libro abierto, no cuenta para Universal.

La EPA no organiza el examen ni imprime las tarjetas. Te examinas con una organización certificadora aprobada por la EPA, que emite una tarjeta de bolsillo en un plazo de 30 días. La certificación no caduca, y tienes que guardar una copia del certificado en tu lugar de trabajo. Los precios, las fechas y si puedes examinarte en línea los fija la organización que elijas. Una cosa que sorprende a mucha gente: el aire acondicionado de los vehículos no es Section 608. Ese trabajo entra en la Section 609, que es una certificación aparte.

Cómo usar esta muestra

Las 15 preguntas siguen el orden del examen: seis de Core, luego tres de Type I, cuatro de Type II y dos de Type III. Si solo te presentas a Core y Type I, hazlas todas igualmente, porque las preguntas de Type II sobre velocidad de recuperación y señales de fuga son buena base para cualquier técnico.

Tres temas merecen atención extra. El primero son las tres R, recover, recycle y reclaim (recuperar, reciclar y regenerar), que es fácil confundir. El segundo es la tabla de evacuación, donde el vacío exigido depende del tipo de aparato, de su carga de refrigerante y de cuándo se fabricó tu equipo de recuperación. El tercero es la seguridad, sobre todo nitrógeno frente a oxígeno y el límite de llenado del 80 por ciento de las botellas. Si fallas uno de estos aquí, repasa el tema entero, no solo ese dato.

Algunas cifras del examen han cambiado con los años, como los umbrales de reparación de fugas, las fechas de eliminación progresiva y la multa máxima, y normas más recientes bajo la AIM Act ahora cubren también los equipos con HFC. Esta muestra evalúa los conceptos que hay detrás de esas normas, no cifras que cambian. Antes del examen, revisa los requisitos vigentes en las páginas de la EPA sobre la Section 608 en epa.gov y en el manual de estudio de tu organización certificadora.

Cómo StudyPDF crea tests completos de EPA 608 con tu manual

Quince preguntas pueden enseñarte qué sección flojea. No pueden cubrir un examen Universal de 100 preguntas, y un banco de preguntas genérico rara vez coincide con el manual de estudio que te da tu organización certificadora.

StudyPDF parte de tu material. Sube tu manual de estudio de EPA 608, las diapositivas de tu escuela de oficios o fotos de tus apuntes de clase, pulsa Nuevo material y StudyPDF crea exámenes de práctica con esas páginas exactas, divididos por secciones como el examen real y corregidos al final. Cada pregunta se basa en tu material y cada explicación cita de dónde sale la respuesta.

No necesitas ningún documento para empezar. Nombra un tema, por ejemplo la recuperación en Type III o las tres R, y Bo lo prepara con sus conceptos clave para que puedas crear cuestionarios sobre él. Tus resultados registran qué conceptos sigues fallando, así que el siguiente cuestionario puede ir a por ellos. Empezar es gratis, y el plan gratis cubre unos cuatro materiales por semana.