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What evacuation level must be reached for a low-pressure appliance?

25 mm Hg absolute, for equipment of any age.

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  1. 10 inches of mercury vacuum
  2. 0 psig
  3. 25 mm Hg absolute ✔

Why: Low-pressure appliances are evacuated much deeper than other types. The required level is 25 mm of mercury absolute pressure. It is the same whether the recovery equipment was made before or after November 15, 1993.

Huh, didn't know that: Low-pressure is the only class whose Table 1 level is stated in absolute pressure, not inches of vacuum.

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References

Answer: 25 mm Hg absolute. Low-pressure appliances are evacuated much deeper than other types. The required level is 25 mm of mercury absolute pressure. It is the same whether the recovery equipment was made before or after November 15, 1993.

  1. 40 CFR 82.156 Required practices (Cornell LII) www.law.cornell.edu/cfr/text/40/82.156
    Low-pressure appliance 25 mm Hg absolute 25 mm Hg absolute.
    Checked 2026-10-10.

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Trades & ShopWhy do techs evacuate a system with a vacuum pump at the end of service?Trades & ShopInstead of recovering a percentage, a technician can evacuate a small appliance to what vacuum?Trades & ShopMedium-pressure appliance under 200 lb, recovery equipment made after November 15, 1993. Evacuate to how many inches of mercury vacuum?

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