Approximately what inches-of-mercury vacuum reading corresponds to the 25 mm Hg absolute recovery level for low-pressure appliances?
a.About 4 inches Hg vacuum
b.About 29 inches Hg vacuum
c.About 10 inches Hg vacuum
d.About 15 inches Hg vacuum
Explanation
25 mm Hg absolute is a deep vacuum equal to roughly 29 inches of mercury vacuum on a compound gauge, since atmospheric pressure is about 760 mm Hg, or 29.9 inches Hg. That is far deeper than the 0 to 15 inches Hg levels that 40 CFR §82.156 Table 1 sets for very-high-, high- and medium-pressure appliances. It reflects how completely a low-pressure chiller must be emptied.
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Related questions on this topic
- 40 CFR §82.152 classifies appliances by their refrigerant's liquid-phase saturation pressure at 104°F. Which range makes an appliance low-pressure?
- Which gas is safe to use, along with a trace of refrigerant, to raise pressure in a low-pressure appliance for leak detection?
- The 25 mm Hg absolute recovery requirement for low-pressure appliances applies to:
- Non-condensable gases such as air that collect in a low-pressure chiller will:
- Compared with older designs, a high-efficiency purge unit is desirable because it:
- A technician wants to warm the refrigerant in a low-pressure chiller to speed recovery. Which method is acceptable?
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