In a low pressure refrigeration system,...

🔍 Key Concepts

• Low pressure refrigeration systems often operate below atmospheric pressure on part of the system, which can cause air and non‑condensables to be drawn in if leaks exist. • Purge recovery units are designed to remove air and non‑condensable gases that collect at the top of the condenser or in the purge drum. • Think about where a leak to atmosphere would most likely allow air to enter and therefore cause the purge unit to run more frequently.

💭 Think About

• Ask yourself: does the purge unit run excessively when there is too much refrigerant in the system, or when there is too much air and non‑condensables? What condition would introduce more air? • Consider the pressure relationship: which side of a low pressure system (high side vs low side) can be below atmospheric pressure during operation, making it more likely to suck air in through leaks? • Eliminate choices that would not significantly increase the amount of air/non‑condensables entering the system, even if they might cause other performance issues.

✅ Before You Answer

• Verify which parts of a low pressure system operate below atmospheric pressure during normal conditions. • Confirm what the primary purpose of the purge recovery unit is: removing refrigerant or removing air/non‑condensables. • Check which type of system leak (high side vs low side) would tend to result in an inward leak of air, rather than an outward leak of refrigerant.

In a low pressure refrigeration system, excessive running of the purge recovery unit generally indicates which probable condition?

faulty purge system vent valve

overcharged system

system leaks on the low side

system leaks on the high side

🔍 Key Concepts

💭 Think About

✅ Before You Answer