Why should a technician not go above 10 psig when leak testing an R-123 chiller?

Leak detection · EPA 608 Type III. The correct answer, and the reasoning behind it.

Pressurizing low-pressure systems for leak tests, signs of leaks, inspections and reports.

The question

Why should a technician not go above 10 psig when leak testing an R-123 chiller?

• ATo stay safely below the rupture disc settingCorrect answer
• BNitrogen dissolves into R-123 above 10 psig
• CTable 1 caps test pressures at 10 psig
• DThe purge unit shuts down above 10 psig

Why “To stay safely below the rupture disc setting” is correct

Low-pressure chiller shells are built for low pressures and protected by a rupture disc, which on Trane CenTraVac chillers breaks at 15 psig. Pushing a test past 10 psig risks blowing the disc and releasing the whole charge, so 10 psig is the commonly taught ceiling. A manufacturer may set a lower one, such as Trane's 8 psig.

Source: EPA: Test Topics; Trane CVHE-SVX005E-EN, CenTraVac IOM (15 psig rupture disk); Trane CTV-SVX05H-EN, R-123 handling guide (8 psig leak test)

Why the other answers are wrong

• Nitrogen dissolves into R-123 above 10 psig — Dissolving nitrogen is not why the limit exists.
• Table 1 caps test pressures at 10 psig — Table 1 sets evacuation levels, not leak test pressures.
• The purge unit shuts down above 10 psig — The purge unit is not the reason for the test pressure limit.

Practice more of this

More EPA 608 Type III practice questions, or see every EPA 608 practice test.