Reduction

1                 Spirit reduction formula

        1.1                       Variable table

                            V1 = Volume of high strength spirit litres
                                   V2 = Volume of reduced spirit litres
                                   D1 = Density of sprit at high strength
                                   D2 = Density of sprit at reduced strength
                                   WR = Volume of water required for reduction litres
                                   SI = Initial strength %
                                   SF = Final strength %
                                   LA = Litres of alcohol
                                   MI + Mass of product before reduction kg
                                   MF + Mass of product after reduction kg

       1.2            Calculate Final volume of reduced spirit

              Calculate litres of alcohol before reduction.      = V1 X S1

        State required strength of reduced spirit           = SF

        Final volume                                                     V2 = V1 x S1 litres
                                                                                               SF

 

      1.3 Calculate volume of water required for reduction

      Mass of product before reduction                   MI = V1 x D1 kg

      Mass of product after reduction                     MF = V2 x D2 Kg

      Water required                                              WR = MF –MI litres

 

2       Sample calculation.

       Final volume

      1000 litres of spirit at 90%. Requires to be reduced to 65%

      Litres of alcohol is 1000 x 90 / 100 = 900 La

      At 65 %                   Volume ( V2 ) = 900 / 65 x 100 = 1384 litres

      Water required

      Use spirit tables for SG.

     SG at 90% and temp 15 Deg C = 0.8334
     SG at 65% and temp 15 deg C = 0.9016

     MI = 1000 x 0.8334 = 833.4 kg

     M2 = 1384 x 0,9016 = 1248 kg.

     Water required = M2 –M1 litres. = 1248 –833 = 415 litres.

     Notes.

     1/           Density is taken from the “practical alcohol tables”

     2/           The litres of alcohol is a constant regardless of strength.

    3/           Bulk contraction takes place due to differences in spirit & water molecular size

    4/          The mass of the vat contents is volume x density.
                 If only water has been added to a vat of spirit, the change in mass must equal the
                 mass of water added.
                 Water is nominally 1 litre = 1 kg.