amount of vacuum in inches of mercury to boil water

[seresh]

I need to boil some water but can only get the temp to 196.73 degrees F. What amount of vacuum, in inches of mercury, do I need to boil my water? tia

[Guest]

I need to boil some water but can only get the temp to 196.73 degrees F. What amount of vacuum, in inches of mercury, do I need to boil my water? tia

It makes little sense to specify vacuum, as that will depend on the pressure from which you measure. You really need to know the absolute pressure.

196.73 °F = 91.517 °C
The Handbook of Chemistry & Physics has a table which gives vapor pressure vs temp.
91.4 °C, 554.35 mm Hg
91.6 °C, 558.53 mm Hg

Interpolating at 91.517 °C, 556.80 mm Hg, or 74.23 kPa (742.3 mbar). Standard atm. pressure (sea level) is 1013.25 mbar. In std. atmosphere profile used for aircraft, this is equivalent to pressure at about 2505 m of elevation.