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Use these eight questions to identify which low-pressure concepts deserve another study session. Choose one answer, then explain why the closest alternative fails before reading the explanation.
This is original, independent educational practice - not official EPA questions, a full exam, or a readiness prediction. The group labels follow EPA’s public Type III outline (opens in a new tab). That outline is a learning map; current regulations and equipment instructions determine applicable requirements. These scenarios teach concepts, not chiller operation.
1. Interpret excessive purging
Type III group: Leak Detection
An R-123 centrifugal chiller’s purge pump-out activity rises markedly above its established pattern. What does that suggest?
Read answer and explanation
Answer: B. R-123 chillers can have subatmospheric sections that admit air. Excessive purging is a clue, not a specific leak diagnosis. A fails because leakage need not flow outward. Trane also identifies operating conditions and settings as influences on purge activity. Trane PRGD manual, pp. 7, 20, 29 (opens in a new tab)
2. Separate purging from recovery
Type III group: Refrigeration
Which description best captures a low-pressure chiller purge unit’s purpose?
Read answer and explanation
Answer: A. Noncondensables can increase condenser pressure and reduce efficiency. A purge removes them. B confuses that function with recovering the appliance’s refrigerant charge. Trane PRGD manual, p. 7 (opens in a new tab)
3. Account for refrigerant vapor
Type III group: Recovery Techniques
A study note says, “Once bulk liquid is recovered from a low-pressure chiller, recovery is complete.” What is the missing distinction?
Read answer and explanation
Answer: D. EPA explicitly includes recovery of vapor as well as liquid in this Type III group. C mistakes removal of one refrigerant phase for removal of both. Liquid removal alone does not establish completion. EPA Type III recovery techniques (opens in a new tab)
4. Classify a major repair
Type III group: Recovery Requirements
A proposed R-123 chiller repair involves removing its compressor. Which fact makes it “major” under §82.152?
Read answer and explanation
Answer: C. Removal of a listed component meets the definition. D incorrectly attaches the time condition to component removal. The separate opening-based criterion requires both more than four square inches of flow area and more than 15 minutes uncovered. 40 CFR 82.152 (opens in a new tab)
5. Interpret pressure rebound
Type III group: Recovery Requirements
A written recovery scenario reports that a low-pressure appliance briefly reaches its applicable evacuation target, then pressure rises. Which interpretation is justified?
Read answer and explanation
Answer: D. EPA identifies residual refrigerant as a reason for this check; the rise does not uniquely prove C. EPA Type III recovery requirements (opens in a new tab) Also distinguish the appliance’s evacuation obligation under §82.156 (opens in a new tab) from recovery-equipment certification under §82.158 (opens in a new tab): certification alone does not demonstrate completed recovery.
6. Read the pressure classification correctly
Type III group: Refrigeration
Which criterion defines a low-pressure appliance under §82.152?
Read answer and explanation
Answer: C. Classification uses a refrigerant property at a specified temperature. Here, psia means absolute pressure. A substitutes a momentary gauge reading for that classification criterion; evacuating another appliance does not reclassify it. 40 CFR 82.152 (opens in a new tab)
7. Classify the cooling use
Type III group: Leak repair requirements
An office’s comfort-cooling chiller contains only R-123, an ozone-depleting HCFC (opens in a new tab), with a 100-pound full charge. A service addition replacing leaked refrigerant produces a properly calculated annual leak rate of 12%. Which §82.157 threshold applies?
Read answer and explanation
Answer: A. The rate exceeds the applicable 10% threshold. B confuses a commercial building with commercial refrigeration: the appliance’s use determines the category. The refrigerant and full charge put this scenario within §82.157’s scope. 40 CFR 82.157(a)–(c) (opens in a new tab)
Do not extend that scope to every substitute refrigerant. Since January 1, 2026, §84.106 (opens in a new tab) separately covers certain HFC/substitute appliances with at least 15 pounds, excluding solely ODS appliances and the residential and light commercial air-conditioning and heat-pump subsector.
8. Understand detector selectivity
Type III group: Safety
For R-123 area monitoring, why does Chemours prefer compound-specific detectors over halogen-selective detectors?
Read answer and explanation
Answer: B. Compound-specific detection targets the individual refrigerant. D reverses the advantage: broader chemical-family detection can respond to substances other than R-123. Chemours conditions use of halogen-selective R-123 area monitors on other halogen compounds being extremely unlikely nearby. This is a selectivity distinction, not an installation specification. Chemours Freon 123 bulletin, pp. 15–16 (opens in a new tab)
Add the objective groups behind your missed answers to your study plan.
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