Ethanol Water

Overview

Engineering reference data for Ethanol Water in water systems.

Key Formulas

Hydrostatic Pressure

$P = \rho g h$

Pressure due to water column.

Flow Rate

$Q = A v$

Area × velocity.

Variables

Calculation Examples

1. Interpolating Freezing Point Concentration

The concentration for a target freezing point can be estimated using linear interpolation between two known data points from the table.

Formula: $C_c = \left(\frac{C_B - C_A}{t_B - t_A}\right)(t_c - t_A) + C_A$

Where:

• $C_A, C_B$ = known ethanol concentrations (% by volume)
• $t_A, t_B$ = corresponding freezing points (°C)
• $t_c$ = target freezing point (°C)

Example: Find the ethanol concentration for a freezing point of -20°C. Using points from the table: $C_A = 30\%$ at $t_A = -15°C$, $C_B = 40\%$ at $t_B = -23°C$. $C_c = \left(\frac{40\% - 30\%}{-23°C - (-15°C)}\right)(-20°C - (-15°C)) + 30\% = 36.25\%$

2. Mixing to Achieve a Target Concentration

When mixing a concentrated ethanol-water solution with water, use a volume balance.

Formula: $C_s V_s = C_m (V_s + V_w)$

Rearranged for added water volume $V_w$: $V_w = \frac{(C_s - C_m)}{C_m} V_s$

Where:

• $C_s$ = concentration of the initial solution
• $V_s$ = volume of the initial solution
• $C_m$ = target concentration in the final mix
• $V_w$ = volume of clean water to add

Example: To make a 36.25% solution (freezing point -20°C) from a 90% ethanol-water solution: $V_w = \frac{(0.90 - 0.3625)}{0.3625} V_s = 1.48 V_s$ This means for every liter of 90% solution, add 1.48 liters of water.

Alternative Solutions

Common alternatives to ethanol-based water solutions for freeze protection include:

• Ethylene glycol based water solutions
• Propylene glycol based water solutions
• Methanol based water solutions

Warning: Pure ethanol and high-concentration solutions have HIGH flammability. Always consider flash point data (see table above) for safe handling.

Interactive Charts

References

• Original Source