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# Water - Boiling Points at Vacuum Pressure

## Online calculator, figures and tables giving the boiling temperatures of water in varying vacuum, SI and Imperial units.

The boiling point of a substance is the temperature at which the vapor pressure of the liquid equals the pressure surrounding the liquid, and the liquid changes into a vapor. The boiling point of a liquid varies depending upon the surrounding pressure.

A liquid in a partial vacuum has a lower boiling point than when that liquid is at atmospheric pressure.

### Online Water Boiling Point Calculator

The calculator below can be used to calculate the water boiling point at given, absolute pressures.
The output temperature is given as °C, °F, K and °R.

Note! Pressure must be within the ranges 0-1000 mbara, 0-14.7 psia, 0-760 mm Hg or 0-30 in Hg.

Pressure

Choose the actual unit of pressure:

mbara psia mm Hg in Hg

Below, figures and tables show the boiling point of water at varying vacuum.

See Water and Heavy Water  for thermodynamic properties at standard condtions.
See also other properties of Water at varying temperature and pressure: Boiling points at high pressure, Density and specific weightDynamic and kinematic viscosity, Enthalpy and entropy, Heat of vaporization, Ionization Constant, pKw, of normal and heavy water, Melting points at high pressure, Prandtl numberProperties at Gas-Liquid Equilibrium Conditions, Saturation pressure, Specific gravity, Specific heat (heat capacity), Specific volume, Thermal conductivity, Thermal diffusivity and Vapour pressure at gas-liquid equilibrium.

Boiling point as function of the pressure, given as "mm Hg below  standard atmospheric pressure":
(= Vacuum of e.g. 100 mm Hg is the same as [760-100]=660 mm Hg absolute pressure)

The table shows the water boiling temperature at different vacuum pressure.
Vacuum is given as absolute pressure and pressure "below standard atmospheric pressure" (1 bara = 0 vacuum):

For full table with Vacuum and Water Boiling Point - rotate the screen!

 Absolute pressure Vacuum (below standard atmospheric pressure) Water boiling point [Microns][μm Hg] [in Hg] [psia] [mbara][100*Pa] [in Hg] [mmHg][Torr] [mbar][100*Pa] [°C] [°F] 760000 29.92 14.696 1013.3 0 0 0 100 212 635000 25.00 12.279 846.6 4.92 125.0 167 96 205 525526 20.69 10.162 700.6 9.23 234.4 313 90 194 500000 19.69 9.668 666.6 10.24 260.1 347 89 192 355092 13.98 6.866 473.4 15.94 404.9 540 80 176 233680 9.200 4.519 311.5 20.72 526.3 702 70 158 200000 7.874 3.867 266.6 22.05 560.1 747 67 152 149352 5.880 2.888 199.1 24.04 610.6 814 60 140 100000 3.937 1.934 133.3 25.98 659.9 880 52 125 92456 3.640 1.788 123.3 26.28 667.5 890 50 122 55118 2.170 1.066 73.48 27.75 704.9 940 40 104 31750 1.250 0.614 42.33 28.67 728.2 971 30 86 25400 1.000 0.491 33.86 28.92 734.6 979 27 80 22860 0.900 0.442 30.48 29.02 737.1 983 24 76 20320 0.800 0.393 27.09 29.12 739.6 986 22 72 17780 0.700 0.344 23.71 29.22 742.2 990 21 69 15240 0.600 0.295 20.32 29.32 744.7 993 18 64 12700 0.500 0.246 16.93 29.42 747.3 996 15 59 10160 0.400 0.196 13.55 29.52 749.8 1000 12 53 7620 0.300 0.147 10.16 29.62 752.3 1003 7 45 4572 0.180 0.088 6.10 29.74 755.4 1007 0 32 2540 0.100 0.049 3.39 29.82 757.4 1009.82 -6 21 1270 0.050 0.025 1.69 29.87 758.7 1011.51 -14 6 1000 0.039 0.019 1.33 29.88 759.0 1011.85 -17 1 500 0.020 0.0097 0.67 29.90 759.5 1012.53 -24 -12 300 0.012 0.0058 0.40 29.91 759.7 1012.87 -29 -21 254 0.010 0.0049 0.34 29.91 759.7 1012.87 -31 -24 127 0.005 0.0025 0.17 29.92 759.8 1013.04 -37 -35 100 0.0039 0.0019 0.13 29.92 760.0 1013.21 -40 -40 50 0.0020 0.0010 0.07 29.92 760.0 1013.21 -46 -50 25.4 0.0010 0.0005 0.03 29.919 759.9 1013.17 -51 -60 12.7 0.0005 0.00025 0.017 29.9195 760.0 1013.19 -57 -70 2.54 0.0001 0.00005 0.003 29.9199 760.0 1013.20 -68 -90

• 0% vacuum = 760 torr = 14.7 psia = 29.92 in mercury abs = 101.4 kPa abs
• 50% vacuum = 380 torr = 7.3 psia = 15 in mercury abs = 50.8 kPa abs
• 99.9% vacuum = 1 torr = 0.01934 psia = 0.03937 in mercury abs = 1.3 kPa abs

## Related Topics

• Thermodynamics - Thermodynamics of steam and condensate systems.
• Boiling Points - Boiling points of elements, products and chemical species at varying conditions.
• Material Properties - Material properties of gases, fluids and solids - densities, specific heats, viscosities and more.
• Steam and Condensate - Steam & condensate systems- properties, capacities, pipe sizing, systems configuration and more.
• Thermodynamics - Work, heat and energy systems.
• Water Systems - Hot and cold water service systems - design properties, capacities, sizing and more.
• Fluid Mechanics - The study of fluids - liquids and gases. Involving velocity, pressure, density and temperature as functions of space and time.

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Temperature

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oF

Length

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naut miles

Area

m2
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Volume

m3
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Weight

kgf
N
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Velocity

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Pressure

Pa (N/m2)
bar
mm H2O
kg/cm2
psi
inches H2O

Flow

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cfm

3 30