🔍 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.