# OIML Calculator

### Introduction

The OIML Calculator solves the general formula for calculating the densities of mixtures of ethanol and water found in International Recommendation 22: International Alcoholometric Tables by the International Organisation of Legal Metrology (OIML, 1973).

### Input/Output Field Definitions

Density – The density of the ethanol/water mixture.  This field can be either an input field or an output field.  If it is used as an input field, the alcohol content is calculated from the entered values of density and temperature.  If alcohol content is entered, density is calculated.  Range: 771.93 to 1000 kg/m3

Temperature – The temperature at which to calculate the density or alcohol content for the ethanol/water mixture.  If the temperature is changed, either the density or alcohol content will be recalculated, depending on which one was entered last.  Range: -20°C (-4°F) to 40°C (104°F)

Alcohol Content – The alcohol content of the ethanol/water mixture.  This field can be either an input field or an output field.  If it is used as an input field, the density is calculated from the entered values of alcohol content and temperature.  If density is entered, alcohol content is calculated.  Range: 0% to 100% vol/vol

### Calculation Details

The OIML Calculator uses the general formula for calculating the densities of mixtures of ethanol and water found in International Recommendation 22: International Alcoholometric Tables by the International Organisation of Legal Metrology (OIML, 1973).  The general formula has the form:

 ρ = A1 + ΣiAipi-1 + ΣjBj(t-20)j + ΣmΣnCm,npn(t-20)m (5-53)

where:

ρ = density of ethanol/water mixture, kg/m3

p = ethanol concentration by weight, fraction

t = temperature, ºC

A, B, C = coefficients

i = 2 to 12

j = 1 to 6

m = 1 to 5

n = 1 to 11

Given an alcohol content and a temperature, equation (5-53) can be solved directly for the density of the mixture.  Given a density and a temperature, FermCalc calculates the associated alcohol content using an iterative technique.