Freezing temperature and flash point for ethanol based water solution or brine
Ethanol based Water Solutions Freezing Point
(% by volume)
Flash Points of Ethanol based Water Solutions
The flash point of a chemical is the lowest temperature where it will evaporate enough fluid to form a combustible concentration of gas. The flash point is an indication of how easy a chemical may burn.
(% by weight)
- HIGH flammability if pure
Alternatives to Ethanol based Water Solutions
- Ethylene glycol based water solutions
- Propylene glycol based water solutions
- Methanol based water solutions
Example - Ethanol Concentration at Freezing Point at -20oC
By using linear interpolation between two known concentrations and their freezing points - the concentration at a third freezing point can be calculated as
CC = [(CB - CA) / (tB - tA)] (tC - tA) + CA (1)
C = concentration in ethanol - water solution
t = freezing point (oC, oF)
A, B = known freezing points
C = calculated freezing point
The ethanol concentration with freezing point at -20oC can be calculated by interpolating the concentration between freezing point -15oC and -23oC in the table above.
Cc = [((40 %) - (30 %)) / ((-23 oC) - (-15 oC))] ((-20 oC) - (-15 oC)) + (30 %) = 36.25 %
Note that this calculation is simplified by assuming that the concentration vs. freezing point follows a straight line. This not necessary correct.
If a 90% ethanol-water solution shall be mixed with clean water to achieve a freezing point of -20oC (ethanol concentration 36.25% (0.3625)) - the amount of added water can be calculated with volume balance - the amount of ethanol before mix is the same as after the mix:
C Vs = Cm (Vs + Vw) (2)
Vs = volume of the ethanol - water solution (liter, gallon)
Cm = concentration in mix
Vm = volume of mix (liter, gallon)
Vw = volume of the added clean water (liter, gallon)
Rearranging the equation to express the volume of water added to the mixture
Vw = (C - Cm) Vs / Cm (2b)
Substituting with values
Vw = (0.9 - 0.3625) Vs / 0.3625
= 1.48 Vs
- for every liter 90% ethanol-water solution 1.48 liter of clean water must be mixed in to achieve an ethanol concentration of 36.25 % and freezing point -20oC.