A high-pressure centrifugal chiller,...

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Question 1 of 2066636eee28f7522a1c51eb06

A high-pressure centrifugal chiller, currently charged with R-134a, is being evaluated for leak testing. The machine is idle, the pressures equalized at 10 psig, with an ambient temperature of 60°F. Using the leak test procedures decision tree and the R-134a pressure-temperature chart, what statement is TRUE? RA-0094_1.jpgRA-0094_2.jpg

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Question 1 of 20

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🔍 Key Concepts

• Use the R-134a pressure-temperature chart to find the normal saturated pressure at 60°F. • Compare the actual idle/equalized pressure (10 psig) to the expected saturated pressure at that temperature to decide if a leak is suspected. • Follow the decision tree thresholds carefully: note the branches that use 15 psig minimum, 0 psig, and when to raise pressure with refrigerant versus with nitrogen.

💭 Think About

• At 60°F, what pressure does the chart say R‑134a should be at if the system is fully charged and at rest (saturated)? How does this compare to 10 psig? • On the decision tree, which exact path do you follow when the cooler/condenser pressure is below the saturation pressure and also above 0 psig? • Under what specific condition does the chart tell you to add nitrogen up to 70 psig, and under what condition does it tell you to increase pressure using refrigerant only to around 35 psig?

✅ Before You Answer

• Double‑check the R‑134a chart reading at 60°F; the expected pressure should be much higher than 10 psig. • Confirm from the decision tree whether the branch you choose applies when the pressure is greater than 0 psig but less than 15 psig. • Verify whether the chosen branch calls for leak testing after adjusting pressure with refrigerant or after pressurizing with nitrogen to 70 psig.

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