# Volume percent

Physical unit
Unit name Volume percent
Unit symbol ${\ displaystyle \ mathrm {Vol. {\ text {-}} \%, \ \% \; vol, \ \% \; v / v}}$
Physical quantity (s) Volume fraction , volume concentration , volume ratio
Formula symbol ${\ displaystyle \ varphi, \ \ sigma, \ \ psi}$
dimension ${\ displaystyle {\ mathsf {{\ frac {L ^ {3}} {L ^ {3}}} = 1}}}$
In SI units ${\ displaystyle \ mathrm {1 \; Vol. {\ text {-}} \% = 0 {,} 01 \; {\ frac {m ^ {3}} {m ^ {3}}}}}$
Derived from percent

Volume percent or percent by volume , in Austria volume percent , (abbreviation or unit characters : Vol .-% , % vol , % v / v and further variants) is a non-standard modification of the auxiliary unit percent in use in dimensionless ratio of sizes in which a volume of an a different volume is referred to (especially for the content quantities volume fraction φ , volume concentration σ and volume ratio ψ for specifying the content of a substance in a mixture ). The actual size meant should be clearly specified.

## Norms

The volume percentage goes back to the first edition of DIN 1310 "Content of solutions" from April 1926 and is out of date today because it no longer complies with the relevant standards such as the currently valid version

• the DIN 1310 "Composition of mixed phases (gas mixtures, solutions, mixed crystals)" of February 1984
• DIN 5477 “Percent, per mille” from February 1983 and
• of DIN EN ISO 80000-1 "Sizes and units - Part 1: General" from August 2013

corresponds.

According to the latter standard, additions to a unit symbol with the intention of giving information about the special property of the size or the context of the measurement in question are generally not permitted ( terms for units may only contain unit symbols and mathematical symbols). The three standards recommend that instead of information such as “35.2 percent by volume” or “35.2 percent by volume”, expressions should be given in which the content is clearly indicated by its name and / or its symbol and - if the Specifying the size value the auxiliary unit of measurement " percent " should be used - the unit symbol " % " without any additions. For example, if the volume fraction is meant, the following can be formulated: “the volume fraction of substance i is 35.2%” or “ φ i = 35.2%”. The size value can also be specified using a pure decimal number (" φ i = 0.352") or with the aid of a fraction of the same volume units (e.g. " φ i = 0.352  / ") or different volume units (e.g. . " Φ i = 352  l / "), possibly combined with decimal prefixes (e.g. " φ i = 352  ml / l ").

## application

The norms presented above are not yet consistently observed in practice, so that information in percent by volume is still widespread.

In the area of gas mixtures , for example, the methane content in the natural gas or the explosion limits , i.e. H. the minimum or maximum content of a flammable gas in air required for the formation of an explosive mixture, often given in "vol .-%" .

With regard to the application of percentages by volume to mixtures of liquids , the most prominent example is likely to be the alcohol content of alcoholic beverages . The EU regulation 1169/2011 (Food Information Regulation LMIV) even stipulates that for drinks with an alcohol content of more than 1.2 percent by volume, the existing alcohol content must generally be specified in percent by volume, namely by a number with no more than one Decimal place to which the symbol "% vol" must be added. The word "alcohol" or the abbreviation "Alk." Or "alc." May be placed in front of this specification. This is the volume concentration of the ethanol ( σ ethanol ) in the liquid at a reference temperature of 20 ° C.

## Individual evidence

1. volume percent. In: Duden. Bibliographical Institute, accessed May 5, 2016 .
2. a b Standard DIN 1310 : Composition of mixed phases (gas mixtures, solutions, mixed crystals); Terms, symbols. February 1984. Section 2.3.
3. a b DIN 5477 standard: percent, per mille; Terms, application. February 1983. Section 2.1.
4. a b Standard DIN EN ISO 80000-1 : Sizes and units - Part 1: General. August 2013. Sections 6.5.5 and 7.2.1.
5. a b Food Information Regulation (LMIV): Regulation (EU) No. 1169/2011 of the European Parliament and of the Council of October 25, 2011 regarding consumer information about food ... in the consolidated version of February 19, 2014 (PDF; 577 KiB), accessed May 5, 2016 ; Introduction Paragraph 12; Art. 9 Paragraph 1 Letter k; Art. 28; Annex XII.
6. Directive 76/766 / EEC of the Council of July 27, 1976 on the approximation of the laws of the member states relating to alcohol tablets , accessed on May 5, 2016 .
7. Directive 87/250 / EEC of the Commission of April 15, 1987 on the indication of the alcohol content as volume concentration on the labeling of alcoholic foods intended for end consumers , accessed on May 5, 2016 .
8. Spirits Regulation : Regulation (EC) No. 110/2008 of the European Parliament and of the Council of January 15, 2008 on the definition, description, presentation and labeling of spirits as well as the protection of geographical indications for spirits and the repeal of Regulation (EEC) No. 1576/89 in the consolidated version of February 22, 2016 (PDF; 566 KiB), accessed on May 5, 2016 ; Annex I, No. 11.
9. Ordinance on the implementation of the Spirits Monopoly Act (Spirits Tax Ordinance - BrStV) , accessed on May 5, 2016; § 3 "Alcohol Content".