# Ethanol Freeze Protected Water Solutions

## Freezing and flash points of ethanol based water solutions or brines

### Ethanol based Water Solutions Freezing Point

Freezing Point
Ethanol Concentration
(% by volume)
0102030405060708090100
Temperature (oF) 32 25 15 5 -10 -25 -35 -55 -75 -110 -175
(oC) 0 -4 -9 -15 -23 -32 -37 -48 -59 -73 -115

### 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.

Flash Point
Ethanol Concentration
(% by weight)
510203040506070809096
Temperature (oF) 144 120 97 84 79 75 72 70 68 63 63
(oC) 62 49 36 29 26 24 22 21 20 17 17

### Warning

• HIGH flammability if pure

### Alternatives to Ethanol based Water Solutions

#### Example - Ethanol Concentration at Freezing Point at -20oC

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.

(((40%) - (30%)) / ((-23oC) - (-15oC))) ((-15oC) - (-20oC)) + (30%) = 37.3 %

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 37.3% (0.373)) - the amount of added water can be calculated with volume balance - the amount of ethanol before mix is the same as after the mix:

cs Vs = cm (Vs + Vw)                                                        (1)

where

cs = concentration in ethanol - water solution

Vs = volume of the ethanol - water solution (liter, gallon)

cs = 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 = (cs - cm) Vs / cm                                                     (1b)

Substituting with values

Vw = (0.9 - 0.373) Vs / 0.373

= 1.41 Vs

- for every liter 90% ethanol-water solution 1.41 liter of clean water must be mixed in to achieve an ethanol concentration of 37.3% and freezing point -20oC.

## Related Topics

• Material Properties - Material properties for gases, fluids and solids - densities, specific heats, viscosities and more
• Melting point - freezing point - Documents giving melting or freezing point of elements and different kind of chemical species at varying conditions

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