1. How does moisture typically enter the refrigerant system on low-pressure chillers?
- ✔️ Air leaks from areas with gaskets or fittings.
2. What is the maximum test pressure for leak testing a low-pressure centrifugal chiller?
- ✔️ 10 psig.
3. What action should be taken regarding leak testing and repairing a CFC-11 chiller?
- ✔️ Leak test and repair the chiller to reduce refrigerant loss from a purge unit.
4. What is the purpose of a hydrostatic tube test kit?
- ✔️ To determine if a tube leaks.
5. What is the required action when the leak rate exceeds a certain percentage in commercial and
industrial process refrigeration systems?
- ✔️ Systems must be repaired when the leak rate exceeds 35% of the charge per year.
6. What is the typical starting method for refrigerant recovery?
- ✔️ Start with liquid recovery as it is faster.
7. At what pressure does a rupture disc on a recovery vessel for low-pressure refrigerants relieve?
- ✔️ 15 psig.
8. According to ASHRAE Guideline 3-1996, at what pressure level should a system be checked for leaks
during a standing vacuum test?
- ✔️ If the pressure rises from 1 mm Hg to above 2.5 mm Hg.
, 9. What is the primary water source for a recovery unit condensing coil?
- ✔️ Local municipal water supply.
10. What vapor pressure is necessary in the shells before charging with liquid refrigerant when
recharging a refrigeration system with R-11?
- ✔️ 16.9" Hg vacuum.
11. What must be done after recovering the liquid refrigerant?
- ✔️ Recover the vapor refrigerant.
12. According to the EPA, how much refrigerant vapor is typically left in an average 350 ton R-11 chiller
at 0 psig pressure after all liquid has been removed?
- ✔️ Approximately 100 pounds.
13. What can happen when charging refrigerant liquid into a refrigeration system under a 29 inch Hg
vacuum?
- ✔️ System water may freeze.
14. When is it acceptable not to evacuate the system to the required level?
- ✔️ When leaks in the appliance make evacuation to the prescribed level unattainable.
15. Which of the following repairs would always be considered "major" under EPA regulations?
- ✔️ Replacement of the evaporator coil.
16. What method is used to pressurize a low-pressure chiller for non-major repairs under EPA
regulations?
- ✔️ Warming the refrigerant.
17. If using a recovery machine manufactured after November 15, 1993, what is the required evacuation
level for a low-pressure appliance before making a major repair?