Type III — low-pressure appliances: flashcards

All cards

Low-pressure recovery level

25 mm Hg absolute — the only Table 1 row not in inches of vacuum, and age-independent.

Excessive purging

A leak drawing air IN. The system runs below atmospheric pressure.

Pressurising for a leak test

Controlled hot water or a built-in heating device first; nitrogen only as fallback.

Freeze prevention

Circulate or remove chiller water during evacuation, or the tubes freeze and split.

Recharging order

Vapour before liquid, through the evaporator charging valve.

Oil removal

Heat oil to 130 F before removing it, to drive off dissolved refrigerant.