Technical data

Sublimation
The principle of sublimation is briefly explained using the phase
diagram of water (freeze drying of mainly aqueous solutions, see
vapor pressure curve). If the atmospheric pressure is higher than
6.11 mbar, water passes through all three phases (solid, liquid,
gas) when the temperature is lowered or raised. At 6.11 mbar the
melting pressure curve, vapor pressure curve and sublimation
pressure curve meet in one point called triple point. At this point,
all three phases occur in parallel (simultaneously). Below this
point, i.e. when the pressure is lower than 6.11 mbar, the ice is
converted directly from a solid to a gaseous phase on reaching the
sublimation pressure curve (vapor pressure curve above ice).
Vapor pressure curve for ice and water
1mbar = 10²Pa
10 • General Information on Freeze Drying Operating Manual Freeze Dryer ALPHA 1-4 LSC / ALPHA 2-4 LSC