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Canadian Alcoholometric Obscuration Equivalent Tables 1993

Canadian Cataloguing in Publication Data Revenue Canada, Customs, Excise and Taxation Canadian Alcoholometric Obscuration Equivalent Tables

ISBN 0-662-59622-6 DSS cat. no. Rv 31-45/1993

Preface

Our Department takes great pride in the publication of this book of alcoholometric obscuration equivalent tables.

The tables have been constructed to provide users with a simple method of determining the true alcoholic strength of obscured spirits at 20 C.

The book is researched and developed by our Laboratory and Scientific Services Directorate with contributions from a number of specialists both national and international.

Pierre Gravelle
Deputy Minister 1993

Note
These instructions and alcoholometric obscuration equivalent tables have been issued under the authority of the Minister of National Revenue, Canada.

Introduction

All alcoholometric tables relating density to alcoholic strength of spirits are developed based on a mixture of pure water and absolute ethyl alcohol. The presence of other substances in the water-alcohol mixture introduces the phenomenon of obscuration in spirit strength determination.

Obscuration alters the true density reading of a water-alcohol mixture resulting in an erroneous determination of the true strength from alcoholometric tables based on water and alcohol. The degree of obscuration, hence the true density and the true alcoholic strength of the mixture, can be determined using a variety of methods like distillation when used with pycnometry. Methods like gas-liquid chromatography can determine the true alcoholic strength of obscured spirits without prior determination of the true density of the same mixture.

These various methods, although accurate, are time consuming or costly in terms of instrumental requirements. Most commercial spirits contain a degree of obscuration; notable examples are liqueurs with high sugar contents and some dark rums. A quick and dependable method to determine spirit obscuration would be of great benefit to the distilling industry.

The Canadian Alcoholometric Obscuration Equivalent Tables, as constructed, provide an easy means to determine the true alcoholic strength of obscured spirits.

Contents

Basis of Tables

The tables are the cumulative outcome of research carried out in the Laboratory and Scientific Services Directorate and published in the Analyst in March and May of 1982. The conversion of density values into alcoholic strengths was calculated using the general formula established by the International Organization of Legal Metrology (International Recommendation No. 22, Fourth International Conference of Legal Metrology - October 1972, First Edition 1973).

Arrangement and Range of Tables

The tables are constructed according to systematic increments of apparent strength for the complete range from pure water to absolute ethyl alcohol. The obscuration values have a range from 0 to 3 which corresponds to the complete range of alcohol water mixtures containing not more than 10 g/L of dissolved solid content.

Values have been calculated for individual strength steps of 0.1% by volume corresponding to the per cent by volume of absolute ethyl alcohol which must be added to the apparent strength of the spirit at 20 C.

Instruments

Category

lnstruments which may be used for determining alcoholic strength are:

1) approved hydrometers graduated in units of density (kg/m3), at the reference temperature of 20 C, called "hydrometers for alcohol";

2)approved Celsius scale thermometers;

3)any other instruments approved by the Minister.

Certification

Instruments which are used in the determination of alcoholic strength for fiscal purposes must be certified in a manner approved by the Minister of National Revenue, Canada.

Use

The method of using the hydrometers is described in the Canadian Alcoholometric Tables 1980, page xi.

Method for the Determination of Obscuration Based on Dissolved Content

Scope

This method is applicable to alcohol-water mixtures containing not more than 10 g/L of dissolved solids. The alcoholic strength of samples containing more than 10 g/L of dissolved solids or having densities outside the range of the Canadian Alcoholometric Tables 1980 can be determined only after separation of the alcohol from the obscuring material.

This method is not applicable to alcohol-water mixtures whose densities are affected by the presence of material having a volatility that is similar to or higher than the volatility of either ethanol or water. Changes in density caused by such volatile materials as ethyl acetate, methanol, acetone, etc., would render the method unusable. The true alcoholic strength of such samples can be determined only after separation of the alcohol from the mixture by other separation methods.

Definitions

Obscuration means: the difference between the density of an alcohol/water mixture (spirit) containing material which affects the density of the mixture, and the density of the same mixture having that material removed.

Dissolved solids means: any material that remains after evaporating a sample following one of the two prescribed procedures.

Original density means: the density "in vacuo" of the sample as received. Such density value is determined by hydrometry or any other method approved by the Minister and is used to enter the Canadian Alcoholometric Tables 1980. Density unit: kg/m3;

or

the density-in-air of the sample as received. Such density value is determined by pycnometry or any other method approved by the Minister and is used to enter the Canadian Alcoholometric Laboratory Tables. Density unit: kg/L or g/mL.

It should be noted that the original density must be determined at 20 C when pycnometry is used.

Apparent strength means: the value of per cent alcohol by volume (% vol [app] ) corresponding to the value of original density as read from the Canadian Alcoholometric Tables 1980 or from the Canadian Alcoholometric Laboratory Tables. This value is not the true strength of the spirit unless the spirit is not obscured.

Alcoholic Equivalent means: the value of per cent by volume corresponding to a particular obscuration value and its apparent strength; the value is found in the Canadian Alcoholometric Obscuration Equivalent Tables 1993.

Apparatus

Balance: A balance capable of determining mass to within 1 mg or better, inspected annually by a recognized independent balance service representative.

Oven: A convection oven with temperature control for maintaining temperature within 5 C; an explosion proof model must be used in Procedure B.

Bath: A steam bath if procedure A is followed.

Procedure A

1. Dry a clean, glass, porcelain or metal dish of about 100 mL size in an oven at 100-110 C for 15 minutes, let cool in a desiccator and weigh to the nearest milligram or better. Record mass (a) in milligrams.

2. Pipet exactly 10 or 25 mL of the sample as received into the tared dish, evaporate the liquid on the steam bath and dry the residue in the oven at 100-150 C for 30 minutes. Let cool in the desiccator and weigh to the nearest milligram or better. Record the mass (b) in milligrams.

3. Calculate the concentration of dissolved solids by subtracting mass (a) from mass (b) and dividing the difference by the volume of sample used:

Procedure B

Proceed exactly as in Procedure A except modifying step 2. Evaporate the liquid directly in the explosion-proof convection oven at 95-100 C, rather than on a steam bath, and continue drying in the oven for 16 hours at the same temperature. Let cool in a desiccator and weigh to the nearest milligram or better.

Calculation of Obscuration

Multiply the concentration of dissolved solids by 0.3

Obscuration (kg/m3) = 0.3 x concentration (g/L)

Round the result to one place after the decimal point.

Determination of Original Density

Determine the density by hydrometry, pycnometry or any other departmentally approved method. When following Procedures a) or b) of the next paragraph, the original density must be determined at 20 C. When Procedure c) of the next paragraph is used, the original density can be determined at any temperature covered by the 1980 Tables.

Determination of Alcoholic Strength

Procedures a) and b) do not require the use of the Canadian Alcoholometric Obscuration Equivalent Tables 1993. They are, however, still based on the dissolved solid contents and are included to cover related situations in obscuration determination. Only Procedure c) requires the use of the equivalent tables.

a) When the original density was determined as density "in vacuo" subtract the value of obscuration (kg/m3) from the original density of the sample measured at 20 C:

b) When the original density was determined as density-in-air (kg/L), convert the obscuration value to kilograms per litre (kg/L) by dividing by 1000. To obtain the corrected density-in-air, subtract the converted value from the original density of the sample measured at 20 C:

c) When using the Canadian Alcoholometric Obscuration Laboratory Tables 1993, proceed as follows:

Calculation of the Volume of Spirits

The original density without correction must be used to determine the volume of spirits.

a) If original density "in vacuo" was used, find the corresponding value of Factor A in the Canadian Alcoholometric Tables 1980 and multiply the mass of spirits obtained by weighing in air (in kg) by this factor; the result is in litres.

b) If original density-in-air was determined, divide the mass of spirits obtained by weighing in air (in kg) by the density-in-air value (in kg/L); the result is in litres.

Examples of Practical Use

Density "in vacuo" Procedure

Density "in vacuo" = 948.6 kg/m3
Temperature = 25 C
Concentration of dissolved solids = 5 g/L (grams per litre)
Apparent strength of the spirit from the Canadian Alcoholometric Tables 1980 = 37.6%
The obscuration value is obtained by multiplying the concentration of dissolved solids by 0.3
5 g/L x 0.3 = 1.5 kg/m3

From the obscuration tables:

Apparent strength = 37.6%
Obscuration = 1.5 kg/m3
Alcoholic Equivalent = 1.0%
The true strength of the spirit is:
37.6% + 1.0% = 38.6% (percent by volume of absolute ethyl alcohol at 20 C)

Density in air Procedure

Density in air = 0.9821 g/mL
Temperature = 20 C.
Concentration of dissolved solids = 3 g/L (grams per litre)
Apparent strength of the spirit from the Canadian Alcoholometric Laboratory Tables = 11.31%.
The obscuration value is obtained by multiplying the concentration of dissolved solids by 0.3.
3 g/L x 0.3 = 0.9 kg/m3

From the obscuration tables:

Apparent strength = 11.3%
Obscuration = 0.9 kg/m3
Alcoholic Equivalent = 0.8%
The true strength of the spirits is:
11.3% + 0.8% = 12.1% (percent by volume of absolute ethyl alcohol at 20 C).

Tables

ZIP Canadian Alcoholometric Obscuration Equivalent Tables (921 KB/ASCII)

The Obs_tab1.txt file is the Canadian Alcoholometric Obscuration Equivalent Tables 1993 presented in a single matrix format.

The Obs_tab2.txt file is the Canadian Alcoholometric Obscuration Equivalent Tables 1993 presented in a continuous format.

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