Podcast
Questions and Answers
On low-pressure chillers, moisture most frequently enters the refrigerant system through ___
On low-pressure chillers, moisture most frequently enters the refrigerant system through ___
leaks from areas with gaskets or fittings.
What precaution should be taken prior to recovering refrigerant from a chiller suspected of having tube leaks?
What precaution should be taken prior to recovering refrigerant from a chiller suspected of having tube leaks?
Drain the water sides of the evaporator and condenser.
Continuous excessive moisture collection in the purge unit of a low-pressure refrigeration system could indicate what condition?
Continuous excessive moisture collection in the purge unit of a low-pressure refrigeration system could indicate what condition?
The condenser or chiller barrel tubes are leaking.
Which component is particularly susceptible to leaks in low-pressure refrigeration systems with open drive type compressors?
Which component is particularly susceptible to leaks in low-pressure refrigeration systems with open drive type compressors?
Signup and view all the answers
What must a system owner do once the threshold leak rate has been exceeded on any low-pressure system?
What must a system owner do once the threshold leak rate has been exceeded on any low-pressure system?
Signup and view all the answers
When must the leak rate of an appliance using an ozone-depleting refrigerant be calculated?
When must the leak rate of an appliance using an ozone-depleting refrigerant be calculated?
Signup and view all the answers
A chiller containing 150 pounds of HCFC refrigerant is leaking above the leak rate threshold. Unless granted additional time, what must be completed within 30 days?
A chiller containing 150 pounds of HCFC refrigerant is leaking above the leak rate threshold. Unless granted additional time, what must be completed within 30 days?
Signup and view all the answers
A typical setting for the high pressure cut-out control on a recovery unit used for evacuating the refrigerant from a low-pressure chiller is ___
A typical setting for the high pressure cut-out control on a recovery unit used for evacuating the refrigerant from a low-pressure chiller is ___
Signup and view all the answers
Refrigerant removal from a low-pressure system starts with ___
Refrigerant removal from a low-pressure system starts with ___
Signup and view all the answers
What must be done after recovering the liquid refrigerant from a low-pressure chiller?
What must be done after recovering the liquid refrigerant from a low-pressure chiller?
Signup and view all the answers
Approximately how much refrigerant vapor is left in an average 350-ton R-123 chiller at 0 psig once all the R-123 liquid has been removed?
Approximately how much refrigerant vapor is left in an average 350-ton R-123 chiller at 0 psig once all the R-123 liquid has been removed?
Signup and view all the answers
When evacuating a system, the use of a severely oversized vacuum pump could ___
When evacuating a system, the use of a severely oversized vacuum pump could ___
Signup and view all the answers
How do you determine when enough vapor has entered the refrigeration system before you charge refrigerant liquid?
How do you determine when enough vapor has entered the refrigeration system before you charge refrigerant liquid?
Signup and view all the answers
What should you do after reaching the required recovery vacuum on a low-pressure appliance?
What should you do after reaching the required recovery vacuum on a low-pressure appliance?
Signup and view all the answers
Which of the following actions would always be considered 'major' under EPA's regulations?
Which of the following actions would always be considered 'major' under EPA's regulations?
Signup and view all the answers
When should an appliance NOT be evacuated all the way to the prescribed level?
When should an appliance NOT be evacuated all the way to the prescribed level?
Signup and view all the answers
Which of the following methods can be used to pressurize an R-1233zd system for the purpose of opening the system for a non-major repair?
Which of the following methods can be used to pressurize an R-1233zd system for the purpose of opening the system for a non-major repair?
Signup and view all the answers
What evacuation level must technicians recover refrigerant to before disposing of a low-pressure appliance?
What evacuation level must technicians recover refrigerant to before disposing of a low-pressure appliance?
Signup and view all the answers
Which of the following always falls under the EPA definition for 'major maintenance, service, or repair'?
Which of the following always falls under the EPA definition for 'major maintenance, service, or repair'?
Signup and view all the answers
R-123 at a pressure of 18.1 inches Hg vacuum has a saturation temperature of ___
R-123 at a pressure of 18.1 inches Hg vacuum has a saturation temperature of ___
Signup and view all the answers
Why do chillers using low-pressure refrigerants require purge units?
Why do chillers using low-pressure refrigerants require purge units?
Signup and view all the answers
Identify the pressure corresponding to 32°F for R-123.
Identify the pressure corresponding to 32°F for R-123.
Signup and view all the answers
During evacuation of a system containing large amounts of moisture, it may be necessary to prevent freezing by increasing pressure using a gas such as ___
During evacuation of a system containing large amounts of moisture, it may be necessary to prevent freezing by increasing pressure using a gas such as ___
Signup and view all the answers
What should be used to remove ice from sight glasses or viewing glasses?
What should be used to remove ice from sight glasses or viewing glasses?
Signup and view all the answers
Where should the discharge from a rupture disc be piped for venting?
Where should the discharge from a rupture disc be piped for venting?
Signup and view all the answers
Study Notes
Chiller Refrigerant Systems
- Moisture enters low-pressure chillers primarily through leaks at gaskets or fittings.
- Signs of tube leaks include continuous excessive moisture collection in the purge unit.
Refrigerant Recovery Procedures
- Drain water sides of the evaporator and condenser before recovering refrigerant from a suspected leaking chiller.
- Liquid refrigerant removal is the first step in recovering from a low-pressure system, followed by vapor recovery.
- After removing liquid refrigerant, ensure to recover vapor refrigerant for system integrity.
Leak Rate Management
- Once the leak threshold is exceeded in low-pressure systems, repairs must be made to lower the leak rate, or the appliance must be retrofitted or retired.
- Leak rates should be calculated when recharging systems with ozone-depleting refrigerants.
Maintenance and Repair Guidelines
- Major actions under EPA regulations include replacing evaporator coils and compressors.
- Do not evacuate a system fully if leaks make it unattainable.
Equipment Characteristics
- High pressure cut-out controls are typically set at 10 psig on recovery units for low-pressure chillers.
- R-123 chillers at 0 psig retain approximately 100 pounds of vapor refrigerant after liquid removal.
Evacuation and Vacuum Considerations
- An oversized vacuum pump can cause trapped water to freeze during evacuation.
- Technicians must recover refrigerant to 25 mm of Hg absolute before disposing of low-pressure appliances.
Operating Pressures and Temperatures
- R-123 at 18.1 inches Hg vacuum corresponds to a saturation temperature of 40°F.
- The pressure for R-123 at 32°F is 20 inches of Hg vacuum.
Safety and Environmental Precautions
- Use isopropyl alcohol to remove ice from sight glasses or viewing glasses.
- Discharge from rupture discs should be vented outdoors to ensure safety.
Special Techniques
- To open R-1233zd systems for non-major repairs, pressurization can be achieved by warming liquid refrigerant.
- When evacuating systems with excess moisture, preventing freezing may require the introduction of nitrogen gas.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
This set of flashcards focuses on essential knowledge for Type III refrigerant handling, particularly related to low-pressure chillers. Key topics include moisture entry points and precautions before recovering refrigerant. Ideal for students and professionals in HVAC and refrigeration technology.
