Using the illustrated chart giving the boiling point of moisture at various depths of vacuum, with an ambient temperature of 72 °F, what depth of vacuum would be associated with the BEST chance of achieving a dehydration evacuation with a deep vacuum pump? Illustration GS-RA-56

Illustration GS-RA-56: the U.S. Coast Guard has not released this illustration.

Question

Using the illustrated chart giving the boiling point of moisture at various depths of vacuum, with an ambient temperature of 72 °F, what depth of vacuum would be associated with the BEST chance of achieving a dehydration evacuation with a deep vacuum pump? Illustration GS-RA-56

Illustration GS-RA-56: the U.S. Coast Guard has not released this illustration.

Accepted Answer

Option D: 29.99" Hg or 254 microns of Hg absolute. Effective dehydration requires lowering the boiling point of water below ambient temperature to induce phase change. At 72 °F, water boils at approximately 1,000 microns. Achieving 254 microns ensures complete moisture removal by maintaining a deep vacuum, far exceeding the vapor pressure threshold required for efficient system evacuation and contaminant removal.