Test EPA 608 USA: Core, Type I, II e III

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Tutte le 15 domande a colpo d'occhio

Preferisci leggere prima di iniziare? Qui sotto trovi tutte le domande del test. Risposte e spiegazioni restano chiuse finché non le apri.

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

   • A. Nitrogen
   • B. Chlorine
   • C. Carbon
   • D. Hydrogen
   Mostra risposta e spiegazione

   Risposta: 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
   Mostra risposta e spiegazione

   Risposta: 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.

   Opzioni per lo spazio 1: recover, recycle, reclaim, recharge

   Mostra risposta e spiegazione

   Risposta: 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
   Mostra risposta e spiegazione

   Risposta: 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?

   Seleziona tutte le risposte corrette.

   • 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.
   Mostra risposta e spiegazione

   Risposta: 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
   Mostra risposta e spiegazione

   Risposta: 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.

   Opzioni per lo spazio 1: 1 pound, 2 pounds, 5 pounds, 10 pounds

   Mostra risposta e spiegazione

   Risposta: 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
   Mostra risposta e spiegazione

   Risposta: 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
   Mostra risposta e spiegazione

   Risposta: 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.

    Opzioni per lo spazio 1: 5 pounds, 15 pounds, 50 pounds, 200 pounds

    Mostra risposta e spiegazione

    Risposta: 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
    Mostra risposta e spiegazione

    Risposta: 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?

    Seleziona tutte le risposte corrette.

    • 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
    Mostra risposta e spiegazione

    Risposta: 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
    Mostra risposta e spiegazione

    Risposta: 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
    Mostra risposta e spiegazione

    Risposta: 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?

    Seleziona tutte le risposte corrette.

    • 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.
    Mostra risposta e spiegazione

    Risposta: 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.

Come funziona l'esame EPA 608

La Section 608 del Clean Air Act, la legge federale statunitense sulla qualità dell'aria, impone una certificazione a chiunque esegua manutenzione, assistenza, riparazione o smaltimento di apparecchiature che potrebbero rilasciare refrigerante. La regola è federale, quindi la stessa certificazione vale in ogni stato. Esistono quattro tipi di certificazione. Il Type I copre i piccoli apparecchi, cioè unità sigillate in fabbrica con 5 libbre di refrigerante o meno, come i frigoriferi domestici e i condizionatori da finestra. Il Type II copre le apparecchiature ad alta e altissima pressione, che comprendono la maggior parte dei condizionatori residenziali e commerciali. Il Type III copre le apparecchiature a bassa pressione, soprattutto i refrigeratori centrifughi. Universal significa che hai superato tutti e tre i tipi.

Ogni test include una sezione Core. Secondo la regola dell'EPA, ogni test ha almeno 25 domande del gruppo Core e almeno 25 per ogni tipo per cui ti stai certificando, quindi un esame Universal ha 100 domande. Il punteggio di superamento fissato dalla regola è il 70 per cento per i test Type I, Type II, Type III e Universal a libro chiuso, e l'84 per cento per un test Type I svolto per posta. Type II e Type III vanno sostenuti a libro chiuso con un sorvegliante. Un test Type I per posta, o una sezione Core svolta a libro aperto, non può valere per la Universal.

L'EPA non gestisce l'esame e non stampa direttamente i tesserini. Fai il test con un ente certificatore approvato dall'EPA, che rilascia un tesserino tascabile entro 30 giorni. La certificazione non scade, e devi tenere una copia del certificato sul luogo di lavoro. Prezzi, date e la possibilità di fare il test online li stabilisce l'ente che scegli. Una cosa che sorprende spesso: l'aria condizionata delle auto non rientra nella Section 608. Il lavoro sui climatizzatori dei veicoli ricade sotto la Section 609, che è una certificazione separata.

Come usare questo assaggio

Le 15 domande seguono l'ordine dell'esame: sei domande Core, poi tre per il Type I, quattro per il Type II e due per il Type III. Anche se sostieni solo Core e Type I, falle comunque tutte, perché le domande Type II sulla velocità di recupero e sui segni di perdite sono una base utile per qualsiasi tecnico.

Tre argomenti meritano più attenzione. Il primo sono le tre R, recover, recycle e reclaim (recupero, riciclo e rigenerazione), che è facile confondere. Il secondo è la tabella di evacuazione, dove il vuoto richiesto dipende dal tipo di apparecchio, dalla quantità di carica e da quando è stata prodotta la tua attrezzatura di recupero. Il terzo è la sicurezza, in particolare azoto contro ossigeno e il limite di riempimento delle bombole all'80 per cento. Se qui ne sbagli uno, ripassa tutto l'argomento, non solo il singolo dato.

Alcuni numeri dell'esame sono cambiati negli anni, tra cui le soglie di riparazione delle perdite, le date di dismissione e la sanzione massima, e le regole più recenti dell'AIM Act ora coprono anche le apparecchiature con HFC. Questo assaggio verifica i concetti dietro quelle regole invece dei numeri che cambiano. Prima dell'esame, controlla i requisiti aggiornati sulle pagine EPA Section 608 su epa.gov e nel manuale di studio del tuo ente certificatore.

Come StudyPDF crea test EPA 608 completi dal tuo manuale

Quindici domande possono mostrarti quale sezione è traballante. Non possono coprire un esame Universal da 100 domande, e un archivio di domande generico raramente coincide con il manuale di studio che ti dà il tuo ente certificatore.

StudyPDF parte invece dal tuo materiale. Carica il tuo manuale di studio EPA 608, le slide della scuola professionale o le foto dei tuoi appunti di lezione, premi Nuovo materiale, e StudyPDF crea simulazioni d'esame da quelle pagine esatte, divise in sezioni come il test vero e corrette alla fine. Ogni domanda si basa sul tuo materiale e ogni spiegazione cita da dove viene la risposta.

Per iniziare non ti serve un documento. Indica invece un argomento, per esempio il recupero Type III o le tre R, e Bo lo prepara con i suoi concetti chiave, così puoi crearci sopra dei quiz. I tuoi risultati tengono traccia dei concetti che continui a sbagliare, così il quiz successivo può puntare su quelli. Iniziare è gratis, e il piano gratuito copre circa quattro materiali a settimana.