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EPA 608: Type III — Low-Pressure Appliances

Centrifugal chillers using R-11 and R-123: vacuum operation, purge units, rupture discs and the 25 mm Hg evacuation level.

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What this section covers

Type III is low-pressure appliances — almost always centrifugal chillers using R-11, R-113 or R-123. The low side runs in a vacuum, so leaks draw air in. A purge unit that never shuts up is a leak.

Numbers that decide the section:

  • Leak test: stay at or below 10 psig
  • Rupture disc: 15 psig
  • Major repair evacuation (equipment after November 15, 1993): 25 mm Hg absolute
  • Charge vapor first until you are above freezing, then liquid — frozen evaporator tubes are the classic fail

Type III does not cover split systems. See Type 1 vs Type 2 vs Type 3.

Other EPA 608 sections