Questions and Answers
What is the standard for machine room safety?
What may be necessary during the evacuation of systems with large amounts of water?
Increase pressure by introducing nitrogen to counteract freezing.
What could be indicated by a strong odor during the recovery process?
A compressor burn-out may have occurred.
When charging a low-pressure system, refrigerant should be introduced to the system as a vapor to raise the system's saturation temperature to a minimum of ____ degrees.
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What certification must a technician have to repair a chiller operating with R-22?
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Under ASHRAE Standard 34, how is R-134a classified?
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Where must pressure relief valves be installed when there is more than one?
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Where is the purge unit located in a low-pressure system?
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What is the maximum pressure to use when leak testing a low-pressure chiller?
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Which refrigerant has a safety classification of B-1?
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After removing all liquid from an average 350-ton, low-pressure appliance, how much vapor refrigerant typically remains in the system?
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What can be used to pressurize a chiller system before opening it for a non-major repair?
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In a low-pressure chiller, where do air and other non-condensables collect?
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What is the EPA-required evacuation level for recovery or recycling equipment used on low-pressure systems?
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How long does an equipment owner or operator have to retrofit or retire an appliance that has exceeded the threshold leak rate if it uses 50 pounds or more of an exempt refrigerant?
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What is the burst pressure of the rupture disk on a low-pressure chiller?
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What type of equipment can be worked on with Type III certification?
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Which organization establishes the refrigerant safety group standard?
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What is the most efficient method of leak checking a charged low-pressure refrigeration unit?
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What must the owner keep records of when refrigerant is added to a low-pressure system during service and maintenance if the system charge is 50 pounds or greater?
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Which of the following best describes the refrigerant recovery process from an R-123 system?
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A low-pressure chiller used for comfort cooling must be repaired if it has an annual leak rate of ____ of the total charge.
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Where is refrigerant added to a low-pressure system during the charging process?
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When pressurizing a low-pressure system for leak-detection purposes, what should not be exceeded?
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Because a low-pressure system operates below atmospheric pressure (in a vacuum), what risk do leaks in gaskets or fittings present?
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Study Notes
ASHRAE Standards and Refrigerants
- ASHRAE-15 establishes safety standards for machine rooms.
- Under ASHRAE Standard 34, R-134a is classified as A1, indicating non-flammable and low-toxicity.
- HCFC-123 (R-123) has a safety classification of B-1, indicating higher toxicity.
System Charging and Evacuation
- Vapor refrigerant should be introduced to low-pressure systems, raising the saturation temperature to at least 36 degrees.
- The EPA requires recovery or recycling equipment to achieve evacuation levels of 25 mm of Hg absolute for low-pressure systems.
- During evacuation of water-heavy systems, nitrogen can be introduced to mitigate freezing risks.
Leak Testing and Pressurization
- Maximum pressure for leak testing a low-pressure chiller is 10 psig to avoid damage.
- Controlled hot water can pressure a chiller before non-major repairs.
- The highest efficiency for leak checking involves pressurization using controlled hot water or heater blankets.
Recovery and Maintenance Procedures
- Recovery from an R-123 system begins with liquid removal followed by vapor recovery.
- Equipment owners must document refrigerant added during service if the system has a charge of 50 pounds or more.
- After liquid removal from a 350-ton low-pressure appliance, about 100 pounds of vapor refrigerant typically remains.
Chiller Specifications and Repairs
- A low-pressure chiller with a 10% annual leak rate requires repairs.
- Types I and II certifications are necessary for working on systems using R-22.
- Repairs must occur within 18 months if an appliance exceeds the threshold leak rate and it contains an exempt refrigerant.
Components and Safety
- Pressure relief valves should be installed in parallel when multiple valves are required.
- The rupture disk on a low-pressure chiller will burst at 15 psig, indicating safety level concerns.
- Non-condensables and air accumulate in the top section of low-pressure condensers due to the vacuum operation.
Charging Practices
- Refrigerant is added at the lowest point in the system, often via the evaporator charging valve.
- Low-pressure systems operating below atmospheric pressure are prone to leaks, causing air and moisture ingress through gaskets and fittings.
Studying That Suits You
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Description
Test your knowledge of EPA 608 Type III regulations with these flashcards. Covering critical safety standards and procedures, this quiz will help reinforce your understanding of refrigerant recovery and safety protocols. Perfect for certification preparation or a quick review.
